Dietary Treatment for Overweight and Obesity - How Weight-loss Diets Work

Research demonstrates that weight loss is associated with the length of the diet, pre-diet weight (people who are more overweight tend to lose more weight, more quickly than those who are only mildly overweight), and the number of calories consumed. Any diet that restricts caloric intake such that calories consumed are less than those expended will promote short-term weight loss. The key to weight loss through diet is adherence—if people do not stick to their diets, then they will not lose weight. As early as the 1860s, William Banting, describing the benefits of his low-carbohydrate diet, wrote that "The great charms and comfort of the system are that its effects are palpable within a week of trial and creates a natural stimulus to persevere for a few weeks more."

The successes achieved using regimens that restrict dieters to a single food or food group such as grapefruits, pineapples, or cabbage are probably in part attributable to the human hankering for variety. Limited to just one food, most dieters experience boredom—there is just no appeal to eating the same food at every meal, for days on end, so naturally, less food is consumed. In addition, these diets generally rely on low-calorie foods, so that even if dieters were inspired to consume ten grapefruits per day, their total daily caloric consumption would be about 1,200 calories, which is sufficient to produce weight loss for most people who are overweight. Similarly, diets that involve stringent portion control effectively reduce calories to produce weight loss.

Low-Calorie Diets

Traditional dietary therapy for weight loss generally seeks to create a deficit of 500 to 1,000 calories per day TABLE 5.3 Low-calorie Step I diet "Table 4. Low-Calorie Step I Diet," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)

TABLE 5.3
Low-Calorie Step I diet
Nutrient	Recommended intake
aA reduction in calories of 500 to 1,000 kcal/day will help achieve a weight loss of 1 to 2 pounds/week. Alcohol provides unneeded calories and displaces more nutritious foods. Alcohol consumption not only increases the number of calories in a diet but has been associated with obesity in epidemiologic studies as well as in experimental studies. The impact of alcohol calories on a person's overall caloric intake needs to be assessed and appropriately controlled.
bFat-modified foods may provide a helpful strategy for lowering total fat intake but will only be effective if they are also low in calories and if there is no compensation by calories from other foods.
cPatients with high blood cholesterol levels may need to use the Step II diet to achieve further reductions in LDL-cholesterol levels; in the Step II diet, saturated fats are reduced to less than 7 percent of total calories, and cholesterol levels to less than 200 mg/day. All of the other nutrients are the same as in Step I.
dProtein should be derived from plant sources and lean sources of animal protein.
eComplex carbohydrates from different vegetables, fruits, and whole grains are good sources of vitamins, minerals, and fiber. A diet rich in soluble fiber, including oat bran, legumes, barley, and most fruits and vegetables may be effective in reducing blood cholesterol levels. A diet high in all types of fiber may also aid in weight management by promoting satiety at lower levels of calorie and fat intake. Some authorities recommend 20 to 30 grams of fiber daily, with an upper limit of 35 grams.
fDuring weight loss, attention should be given to maintaining an adequate intake of vitamins and minerals. Maintenance of the recommended calcium intake of 1,000 to 1,500 mg/day is especially important for women who may be at risk of osteoporosis.
SOURCE: "Table 4. Low-Calorie Step I Diet," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
Caloriesa	Approximately 500 to 1,000 kcal/day reduction from usual intake
Total fatb	30 percent or less of total calories
Saturated fatty acidsc	8 to 10 percent of total calories
Monounsaturated fatty acids	Up to 15 percent of total calories
Polyunsaturated fatty acids	Up to 10 percent of total calories
Cholesterolc	<300 mg/day
Proteind	Approximately 15 percent of total calories
Carbohydratee	55 percent or more of total calories
Sodium chloride	No more than 100 mmol/day (approximately 2.4 g of sodium or approximately 6 g of sodium chloride)
Calciumf	1,000 to 1,500 mg/day
Fibere	20 to 30 g/day

with the intent of promoting weight loss of between one to two pounds per week. Low-calorie diets (LCDs) for men usually range from 1,200 to 1,600 calories per day; for women LCDs contain between 1,000 and 1,200 calories per day. Table 5.3 is an example of the recommended percentages of nutrients in an LCD that aims to decrease risk factors for hypertension and high cholesterol as well as cause weight loss.

The most successful LCDs take individual food preferences into account to custom-tailor the diet. Table 5.4 and Table 5.5 show examples of how traditional American cuisine may be used to create a low-calorie diet containing 1,200 and 1,600 calories per day respectively. Table 5.6 incorporates regional Southern cuisine into a reduced-calorie diet. Table 5.7 illustrates how Asian-American cuisine may be adapted to 1,200- and 1,600-calorie-per-day diets, and Table 5.8 shows how Mexican-American cuisine may be adapted for low-calorie diets. Table 5.9 is a sample of a reduced-calorie TABLE 5.4 Sample reduced calorie menus, traditional American cuisine—1,200 calories "Appendix D. Traditional American Cuisine—1,200 Calories," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)diet that vegetarians who eat milk and eggs but no meat or fish can use to lose weight. Food exchanges, such as those shown in Table 5.10, enable dieters to enjoy a variety of foods in their reduced-calorie meals, which can prevent boredom and the tendency to abandon the diet.

TABLE 5.4
Sample reduced calorie menus, traditional American cuisine-1,200 calories
	Calories	Fat (grams)	% Fat	Exchange for
Calories	1,247	Saturated fat, % Kcals	7
Total Carbohydrate, % Kcals	58	Cholstrol, mg	96
Total fat, % Kcals	26	Protein, % Kcals	19
*Sodium, mg	1,043
Note: Calories have been rounded.
1,200: 100% RDA met for all nutrients except vitamin E 80%, vitamin B2 96%, vitamin B6 94%, calcium 68%, iron 63%, and zinc 73%.
*No salt added in recipe preparation or as seasoning. Consume at least 32 ounces of water.
SOURCE: "Appendix D. Traditional American Cuisine—1,200 Calories," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
Breakfast
• Whole wheat bread, 1 medium slice		70		1.2	15	(1 bread/starch)
• Jelly, regular, 2 tsp		30		0	0	(1/2 fruit)
• Cereal, shredded wheat, 1/2 cup		104		1	4	(1 bread/starch)
• Milk, 1%, 1 cup		102		3	23	(1 milk)
• Orange juice, 3/4 cup		78		0	0	(1 1/2 fruit)
• Coffee, regular, 1 cup		5		0	0	(free)
Breakfast total		389		5.2	10
Lunch
• Roast beef sandwich
Whole wheat bread, 2 medium slices		139		2.4	15	(2 bread/starch)
Lean roast beef, unseasoned, 2 oz		60		1.5	23	(2 lean protein)
Lettuce, 1 leaf		1		0	0	(1 vegetable)
Tomato, 3 medium slices		10		0	0
Mayonnaise, low calorie, 1 tsp		15		1.7	96	(1/3 fat)
• Apple, 1 medium		80		0	0	(1 fruit)
• Water, 1 cup		0		0	0	(free)
Lunch total		305		5.6	16
Dinner
• Salmon, 2 ounces edible		103		5	44	(2 lean protein)
• Vegetable oil, 1 1/2 tsp		60		7	100	(1 1/2 fat)
• Baked potato, 3/4 medium		100		0	0	(1 bread/starch)
• Margarine, 1 tsp		34		4	100	(1 fat)
• Green beans, seasoned, with margarine, 1/2 cup		52		2	4	(1 vegetable) (1/2 fat)
• Carrots, seasoned		35		0	0	(1 vegetable)
• White dinner roll, 1 small		70		2	28	(1 bread/starch)
• Iced tea, unsweetened, 1 cup		0		0	0	(free)
• Water, 2 cups		0		0	0	(free)
Dinner total		454		20	39
Snack
• Popcorn, 2 1/2 cups		69		0	0	(1 bread/starch)
• Margarine, 3/4 tsp		30		3	100	(3/4 fat)
Total		1,247		34-36	24-26

Research reveals that reducing fat in the diet is an effective way to reduce calories, and that when low-calorie diets are combined with low-fat diets, better weight loss is achieved than through calorie reduction alone. Further, while very-low-calorie diets that provide about 500 calories per day have been demonstrated to produce greater initial weight loss than the low-calorie diets, the long-term weight loss is not different between the two regimens.

Low-Carbohydrate Diets

During 2004 and 2005 several rigorous research studies reported that low-carbohydrate diets were as effective, or even more effective, in producing short-term weight loss than low-fat diets. The low-carbohydrate diets owed much of their success to adherence—dieters were better able to stick with their diets, and as a result achieved better results. Another hypothesis about the success of low-carbohydrate regimens is that dieters do not feel as hungry as they do on other diets because protein is the most satisfying of the three macronutrients—carbohydrates, fats, and protein.

The scientific premise of low-carbohydrate diets is that consuming certain carbohydrates can cause surges in blood sugar and insulin that not only stimulate appetite TABLE 5.5 Sample reduced calorie menus, traditional American cuisine—1,600 calories "Appendix D. Traditional American Cuisine—1,600 Calories," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)and weight gain, but also may increase risk for diabetes and heart disease. The earliest low-carbohydrate diets viewed all carbohydrates as equally harmful. Increasingly, however, low-carbohydrate diets distinguish between simple and complex carbohydrates, which contain simple or complex sugars.

TABLE 5.5
colspan="7">Sample reduced calorie menus, traditional American cuisine—1,600 calories
		Calories	Fat (grams)	% Fat	Exchange for
Calories	1,613	Saturated fat, % kcals	8
Total Carbohydrate, % kcals	55	Cholesterol, mg	142
Total fat, % kcals	29	Protein, % kcals	19
*Sodium, mg	1,341
Note: Calories have been rounded.
1,600: 100% RDA met for all nutrients except vitamin E 99%, iron 73%, and zinc 91%.
No salt added in recipe preparation or as seasoning. Consume at least 32 ounces of water.
SOURCE: "Appendix D. Traditional American Cuisine—1,600 Calories," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
Breakfast
• Whole wheat bread, 1 medium slice		70		1.2	15.4	(1 bread/starch)
• Jelly, regular, 2 tsp		30		0	0	(1/2 fruit)
• Cereal, shredded wheat, 1 cup		207		2	8	(2 bread/starch)
• Milk, 1%, 1 cup		102		3	23	(1 milk)
• Orange juice, 3/4 cup		18		0	0	(1 1/2 fruit)
• Coffee, regular, 1 cup		5		0	0	(free)
• Milk, 1%, 1 oz		10		0.3	27	(1/8milk)
Breakfast total		502		6.5	10
Lunch
• Roast beef sandwich:
Whole wheat bread, 2 medium slices		139		2.4	15	(2 bread/starch)
Lean roast beef, unseasoned, 2 oz		60		1.5	23	(2 lean protein)
American cheese, low fat and low sodium, 1 slice, 3/4 oz		46		1.8	36	(1 lean protein)
Lettuce, 1 leaf		1		1	0
Tomato, 3 medium slices		10		0	0	(1 vegetable)
Mayonnaise, low calorie, 2 tsp		30		3.3	99	(2/3 fat)
• Apple, 1 medium		8		0	0	(1 fruit)
• Water, 1 cup		0		0	0	(free)
Lunch total		366		9	22
Dinner
• Salmon, 3 ounces edible		155		7	40	(3 lean protein)
• Vegetable oil, 1 1/2 tsp		60		7	100	(1 1/2 fat)
• Baked potato, 3/4 medium		100		0	0	(1 bread/starch)
• Margarine, 1 tsp		34		4	100	(1 fat)
• Green beans, seasoned, with margarine, 1/2 cup		52		2	4	(1 vegetable) (1/2 fat)
• Carrots, seasoned, with margarine, 1/2 cup		52		2	4	(1 vegetable) (1/2 fat)
• White dinner roll, 1 medium		80		3	33	(1 bread/starch)
• Ice milk, 1/2 cup		92		3	28	(1 bread/starch) (1/2 fat)
• Iced tea, unsweetened, 1 cup		0		0	0	(free)
• Water, 2 cups		0		0	0	(free)
Dinner total		625		28	38
Snack
• Popcorn, 2 1/2 cups		69		0	0	(1 bread/starch)
• Margarine, 1/2 tsp		58		6.5	100	(1 1/2 fat)
Total		1,613		50	28

Examples of single sugars from foods include fructose, which is found in fruits, and galactose, which is found in milk products. Double sugars include lactose in dairy products; maltose, which is found in certain vegetables and in beer; and sucrose (table sugar). Examples of complex carbohydrates, often referred to as "starches" are breads, cereals, legumes, brown rice, and pastas. Simple carbohydrates occur naturally in fruits, milk products, and vegetables; at the same time, these foods also contain vitamins and minerals. The simple carbohydrates most nutritionists call "empty calories" are the processed and refined sugars found in candy, table sugar, and sodas, as well as such foods as white flour, sugar, and polished rice (unless they are labeled "enriched" or "fortified" with vitamins or other nutrients).

In addition to distinguishing between simple and complex carbohydrates, low-carbohydrate regimens rely on a measure known as the glycemic index (GI), which ranks foods based on how rapidly their consumption raises blood glucose levels. The GI measures how much TABLE 5.6 Sample reduced calorie menus, Southern cuisine "Appendix D. Southern Cuisine—Reduced Calorie," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)blood sugar increases over a period of two or three hours after a meal. Carbohydrate foods that break down quickly during digestion have the highest glycemic indices. The GI may be used to determine if a particular food will trigger the problematical "carbohydrate-blood sugar-insulin cascade." High-GI foods are those that are rapidly TABLE 5.7 Sample reduced calorie menus, Asian American cuisine "Appendix D. Asian American Cuisine—Reduced Calorie," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)digested and absorbed or transformed metabolically into glucose. These include refined starchy foods such as bread, cereal, pasta, and table sugar. In general, fiber-rich foods are low glycemic. Most vegetables, legumes, and fruits are low-GI foods.

TABLE 5.6
Sample reduced calorie menus, Southern cuisine
		1,600 calories	1,200 calories
Calories	1,653	Calories	1,225
Total carbohydrate, % kcals	53	Total carbohydrate, % kcals	50
Total fat, % kcals	28	Total fat, % kcals	31
*Sodium, mg	1,231	*Sodium, mg	867
Saturated fat, % kcals	8	Saturated fat, % kcals	9
Cholesterol, mg	172	Cholesterol, mg	142
Protein, % kcals	20	Protein, % kcals	21
1,600: 100% RDA met for all nutrients except vitamin E 97%, magnesium 98%, iron 78%, and Zinc 90%.
1.200: 100% RDA met for all nutrients except vitamin E 82%, vitamin B1 & B2 95%, vitamin B 99%, vitamin B 88%, magnesium 83%, iron 56%, and zinc 70%.
*No salt added in recipe preparation or as seasoning. Consume at least 32 ounces of water.
SOURCE: "Appendix D. Southern Cuisine—Reduced Calorie," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
Breakfast
• Oatmeal, prepared with 1% milk, low fat		1/2 cup	1/2 cup
• Milk, 1%, low fat		1/2 cup	1/2 cup
• English muffin		1 medium	—
• Cream cheese, light, 18% fat		1 T	—
• Orange juice		3/4 cup	1/2 cup
• Coffee		1 cup	1 cup
• Milk, 1%, low fat		1 oz	1 oz
Lunch
• Baked chicken, without skin		2 oz	2 oz
• Vegetable oil		1 tsp	1/2 tsp
• Salad:
Lettuce		1/2 cup	1/2 cup
Tomato		1/2 cup	1/2 cup
Cucumber		1/2 cup	1/2 cup
• Oil and vinegar dressing		2 tsp	1 tsp
• White rice		1/2 cup	1/4 cup
• Margarine, diet		1/2 tsp	1/2 tsp
• Baking powder biscuit, prepared with vegetable oil		1 small	1/2 small
• Margarine		1 tsp	1 tsp
• Water		1 cup	1 cup
Dinner
• Lean roast beef		3 oz	2 oz
• Onion		1/4 cup	1/4 cup
• Beef gravy, water-based		1 T	1 T
• Turnip greens		1/2 cup	1/2 cup
• Margarine, diet		1/2 tsp	1/2 tsp
• Sweet potato, baked		1 small	1 small
• Margarine, diet		1/2 tsp	1/4 tsp
• Ground cinnamon		1 tsp	1 tsp
• Brown sugar		1 tsp	1 tsp
• Corn bread prepared with margarine, diet		1/2 medium slice	1/2 medium slice
• Honeydew melon		1/4 medium	1/8 medium
• Iced tea, sweetened with sugar		1 cup	1 cup
Snack
• Saltine crackers, unsalted tops		4 crackers	4 crackers
• Mozzarella cheese, part skim, low sodium		1 oz	1 oz

TABLE 5.7
Sample reduced calorie menus, Asian American cuisine
		1,600 calories	1,200 calories
Calories	1,609	Calories	1,220
Total carbohydrate, % kcals	56	Total carbohydrate, % kcals	55
Total fat, % kcals	27	Total fat, % kcals	27
*Sodium, mg	1,296	*Sodium, mg	1,043
Saturated fat, % kcals	8	Saturated fat, % kcals	8
Cholesterol, mg	148	Cholesterol, mg	117
Protein, % kcals	20	Protein, % kcals	21
1,600: 100% RDA net for all nutrients except zinc 95%, iron 87%, and calcium 93%.
1,200: 100% RDA net for all nutrients except vitamin E 75%, calcium 84%, magnesium 98%, iron 66%, and zinc 77%
*No salt added in recipe preparation or as seasoning. Consume at least 3 ounces of water.
SOURCE: "Appendix D. Asian American Cuisine—Reduced Calorie," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
Breakfast
• Banana		1 small	1 small
• Whole wheat bread		2 slices	1 slice
• Margarine		1 tsp	1 tsp
• Orange juice		3/4 tsp	3/4 tsp
• Milk 1%, low fat		3/4 cup	3/4 cup
Lunch
• Beef noodle soup, canned, low sodium		1/2 cup	1/2 cup
• Chinese noodle and beef salad:
Roast beef		3 oz	2 oz
Peanut oil		11/2 tsp	1 tsp
Soya sauce, low sodium		tsp	1 tsp
Carrots		1/2 cup	1/2 cup
Zucchini		1/2 cup	1/2 cup
Onion		1/4 cup	1/4 cup
Chinese noodles, soft type		1/4 cup	1/4 cup
• Apple		1 medium	1 medium
• Tea, unsweetened		1 cup	1 cup
Dinner
• Pork stir-fry with vegetables:
Pork cutlet		2 oz	2 oz
Peanut oil		1 tsp	1 tsp
Soya sauce, low sodium		1 tsp	1 tsp
Broccoli		1/2 cup	1/2 cup
Carrots		1 cup	1 cup
Mushrooms		1/4 cup	1/2 cup
• Steamed white rice		1 cup	1 cup
• Tea, unsweetened		1 cup	1 cup
Snack
• Almond cookies		2 cookies	—
• Milk 1%, low fat		1/2 cup	1/2 cup

Measurement of GI is a relatively recent practice. It began during the 1990s, following the discovery that specific carbohydrates such as potatoes and cornflakes raised blood sugar faster than others such as brown rice and oatmeal. Harvard University School of Public Health TABLE 5.8 Sample reduced calorie menus, Mexican American cuisine "Appendix D. Mexican American Cuisine—Reduced Calorie," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)

TABLE 5.8
Sample reduced calorie menus, Mexican American cuisine
		1,600 calories	1,200 calories
Calories	1,638	Calories	1,239
Total carbohydrate, % kcals	56	Total carbohydrate, % kcals	58
Total fat, % kcals	27	Total fat, % kcals	26
*Sodium, mg	1,616	*Sodium, mg	1,364
Saturated fat, % kcals	9	Saturated fat, % kcals	8
Cholesterol, mg	153	Cholesterol, mg	91
Protein, % kcals	20	Protein, % kcals	19
1,600: 100% RDA met for all nutrients except vitamin in E 97% and Zinc 84%
1,200: 100% RDNA met for all nutrients except vitamin E 71%, vitamin B1 & B3 91%, vitamin B2 & iron 90%, and calcium 92%.
*No salt in recipe preparation or as seasoning. Consume at least 32 ounces of water.
SOURCE: "Appendix D. Mexican American Cuisine—Reduced Calorie," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
Breakfast
• Cantaloupe		1 cup	1/2 cup
• Farina, prepared with 1% low fat milk		1/2 cup	1/2 cup
• White bread		1 slice	1 slice
• Margarine		1 tsp	1 tsp
• Jelly		1 tsp	1 tsp
• Orange Juice		121 cup	3/4 cup
• Milk, 1%, low fat		21 cup	21 cup
Lunch
• Beef enchilada:
Tortilla, corn		2 tortillas	2 tortillas
Lean roast beef		2 1/2 oz	2 oz
Vegetable oil		2/3 tsp	2/3 tsp
Onion		1 T	1 T
Tomato		4 T	4 T
Lettuce		1/2 cup	1/2 cup
Chili peppers		2 tsp	2 tsp
Refried beans, prepared with vegetable oil		1/4 cup	1/4 cup
• Carrots		5 sticks	5 sticks
• Celery		6 sticks	6 sticks
• Milk, 1%, low fat		1/2 cup	—
• Water		—	1 cup
Dinner
• Chicken taco:
Tortilla, corn		1 tortilla	1 tortilla
Chicken breast, without skin		2 oz	1 oz
Vegetable oil		2/3 tsp	2/3 tsp
Cheddar cheese, low fat and low sodium		1 oz	1/2 oz
Guacamole		2 T	2 T
Salsa		1 T	1 T
• Corn, seasoned with		1/2 cup	1/2 cup
Margarine		1/2 tsp	—
• Spanish rice without meat		1/2 cup	1/2 cup
• Banana		1 large	1/2 large
• Coffee		1 cup	1/2 cup
• Milk, 1%		1 oz	1 oz

researchers used GI to calculate glycemic load—a measure that considers the food's GI and the amount of carbohydrate contained in a single serving. For example, many whole fruits, vegetables, and grains have low glycemic loads, which when consumed prompt a moderate rise in blood glucose and insulin. When the same fruits, vegetables, and grains are squeezed or pulverized into juice or flour, their glycemic load increases—effectively

TABLE 5.9 Sample reduced calorie menus, Lacto-ovo vegetarian cuisine "Appendix D. Lacto-Ovo Vegetarian Cuisine—Reduced Calorie," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, June 1998, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)

TABLE 5.9
Sample reduced calorie menus, Lacto-ovo vegetarian cuisine
Breakfast		1,600 calories	1,200 calories
Calories	1,650	Calories	1,205
Total carbohydrate, % kcals	56	Total carbohydrate, % kcals	60
Total fat, % kcals	27	Total fat, % kcals	25
*Sodium, mg	1,829	*Sodium, mg	1,335
Saturated fat, % kcals	8	Saturated fat, % kcals	7
Cholesterol, mg	82	Cholesterol, mg	44
Protein, % kcals	19	Protein, % kcals	18
1,600:100% RDA met for all nutrients except vitamin E 92%, vitamin B3 97%, vitamin B6 67%, iron 73%, and zinc 68%
1,200:100% RDA met for all nutrients except vitamin E 75%, vitamin B1 92%, vitamin B3 69%, vitamin B659%, iron 54%, and zinc 46%.
*No salt added in recipe preparation or as seasoning. Consume at least 32 ounces of Water.
SOURCE: "Appendix D. Lacto-Ovo Vegetarian Cuisine—Reduced Calorie," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, June 1998, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
• Orange		1 medium	1 medium
• Pancakes, made with 1% lowfat milk and eggs whites		3 4″ circles	2 4″ circles
• Pancake syrup		2T	1T
• Margarine, diet		1 1/2 tsp	1 1/2 tsp
• Milk, 1%, lowfat		1 cup	1/2 cup
• Coffee		1 cup	1 cup
• Milk, 1%, lowfat		1 oz	1 oz
Lunch
• Vegetable soup, canned, low sodium		1 cup	1/2 cup
• Bagel		1 medium	1/2 medium
• Processed american cheese, lowfat		3/4 oz	—
• Spinach salad:
Spinach		1 cup	1 cup
Mushrooms		1/2cup	1/2cup
• Salad dressing, regular calorie		2 tsp	2 tsp
• Apple		1 medium	1 medium
• Iced tea, unsweetened		1 cup	1 cup
Dinner
• Omelette:
Egg whites		4 large eggs	4 large eggs
Green pepper		2 T	2T
Onion		2 T	2T
Mozzarella cheese, made from part skim milk, low sodium		1 oz	1 oz
Vegetable oil		1 T	1/2 T
• Brown rice, seasoned with		1/2cup	1/2cup
Margarine, diet		1/2tsp	1/2tsp
• Carrots, seasoned with		1/2 cup	1/2 cup
Margarine, diet		1/2 tsp	1/2 tsp
• Whole wheat bread		1 slice	1 slice
• Margarine, diet		1 tsp	1 tsp
• Fig bar cookie		1 bar	1 bar
• Tea		1 cup	1 cup
• Honey		1 tsp	1 tsp
• Milk, 1%, lowfat		3/4 cup	3/4 cup

rendering them with the same high glycemic load of sugar water.

After consuming a meal with a high glycemic load, blood sugar rises higher and faster than it does after eating a meal with a low glycemic load. In an effort to recover TABLE 5.10 Food exchange list "Appendix E. Food Exchange List," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)from the resulting peaks and plummets, the brain transmits a hunger signal long before the next meal is due. Wildly fluctuating blood sugar and insulin may result in overeating, which in turn causes overweight. For people who are overweight or physically inactive, another potential danger of consuming foods with high glycemic loads is that they may already be insulin resistant, and overexertion of insulin-producing cells in the pancreas required to metabolize the high glycemic loads may ultimately exhaust their insulin-producing cells, leading to diabetes.

TABLE 5.10
Food exchange list
Within each group, these foods can be exchanged for each other. You can use this list to give yourself more choices.
SOURCE: "Appendix E. Food Exchange List," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
Vegetables contain 25 calories and 5 grams of carbohydrate One serving equals:		Fruits contain 15 grams of carbohydrates and 60 calories One serving equals:
• 1/2 cup	Cooked vegetables (carrots, broccoli, zucchini, cabbage, etc.)	• 1 small	Apple, banana, orange, nectarine
• 1 cup	Raw vegetables or salad greens	• 1 medium	Fresh peach
• 1/2 cup	Vegetable juice	• 1	Kiwi
If you're hungry, eat more fresh or steamed vegetables		• 1/2	Grapefruit
		• 1/2	Mango
Fat free and very low fat milk contains 90 calories and 12 grams of carbohydrate per serving. One serving equals:		• 1 cup	Fresh berries (strawberries, raspberries, or blueberries)
		• 1 cup	Fresh melon cubes
• 8 oz	Milk, fat free or 1 % fat	• 1/8	Honeydew melon
• 1/4 cup	Yogurt, plain nonfat or low fat	• 4 oz	Unsweetened juice
• 1 cup	Yogurt, artificially sweetened	• 4 tsp	Jelly or jam
Very lean protein choices have 35 calories and 1 gram of fat per serving.		Lean protein choices have 55 calories and 2 to 3 grams of fat per serving.
One serving equals:		One serving equals:
• 1 oz	Turkey breast or chicken breast, skin removed	• 1 oz	Chicken—dark meat, skin removed
• 1 oz	Fish fillet (flounder, sole, scrod, cod, haddock, halibut)	• 1 oz	Turkey—dark meat, skin removed
• 1 oz	Canned tuna in water	• 1 oz	Salmon, swordfish, herring, catfish, trout
• 1 oz	Shellfish (clams, lobster, scallop, shrimp)	• 1 oz	Lean beef (flank steak, London broil, tenderloin, roast beef)*
• 3/4 cup	Cottage cheese, nonfat or lowfat	• 1 oz	Veal, roast, or lean chop*
• 2 each	Egg whites	• 1 oz	Lamb, roast, or lean chop*
• 1/4 cup	Egg substitute	• 1 oz	Pork, tenderloin, or fresh ham*
• 1 oz	Fat free cheese	• 1 oz	Lowfat cheese (3 grams or less of fat per ounce)
• 1/2 cup	Beans—cooked (black beans, kidney, chickpeas, or lentils): count as 1 starch/bread and 1 very lean protein	• 1 oz	Lowfat luncheon meats (with 3 grams or less of fat per ounce)
• 1/4 cup		4.5% cottage cheese
		• 2 medium	Sardines
Medium fat proteins have 75 calories and 5 grams of fat per serving		*Limit to 1 to 2 times per week
One serving equals:
• 1 oz	Beef (any prime cut), corned beef, ground beef**	Starches contain 15 grams of carbohydrate and 80 calories per serving One serving equals:
• 1 oz	Pork chop
• 1 eacn	Whole egg (medium)**	• 1 slice	Bread (white, pumpernickel, whole wheat, rye)
• 1 oz	Mozzarella cheese	• 2 slice	Reduced calorie or "lite" bread
• 1/4 cup	Ricotta cheese	• 1/4 (1 oz)	Bagel (varies)
• 4 oz	Tofu (note that this is a heart-healthy choice)	• 1/2	English muffin
**Choose these very infrequently.		• 1/2	Hamburger bun
		• 3/4 cup	Cold cereal
Fats contain 45 calories and 5 grams of fat per serving One serving equals:		• 1/3 cup	Rice, brown or white—cooked
		• 1/3 cup	Barley or couscous—cooked
• 1 tsp	Oil (vegetable, corn, canola, olive, etc)	• 1/3 cup	Legumes (dried beans, peas, or lentils)—cooked
* 1 tsp	Butter	• 1/2 cup	Pasta—cooked
• 1 tsp	Stick margarine	• 1/2 cup	Bulgur—cooked
• 1 tsp	Mayonnaise	• 1/2 cup	Corn, sweet potato, or green peas
• 1 T	Reduced fat margarine or mayonnaise	• 3 oz	Baked sweet or white potato
• 1 T	Salad dressing	• 3/4 oz	Pretzels
• 1 T	Cream cheese	• 3 cups	Popcorn, hot-air popped or microwave (80-percent light)
• 2 T	Lite cream cheese
• 1/8	Avocado
• 8 large	Black olives
• 10 large	Stuffed green olives
• 1 slice	Bacon

Proponents of low-carbohydrate diets observe that consuming foods with low glycemic loads stabilizes blood sugar and insulin to prevent the fluctuations that can cause overeating and may increase risk for diabetes. They also assert that reliance on low-fat diets inadvertently led to diets that were high in simple carbohydrates, and indirectly promoted the observed increase in overweight and diabetes in the United States.

Low-Fat Diets

Low-fat diets reduce caloric intake by reducing fat consumption. Fat has nine calories per gram, while protein and carbohydrates have four calories per gram. TABLE 5.11 Low calorie, lower fat alternatives "Appendix C. Instead of … Replace with …" in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12,2006)These diets rely on the high-fiber content of complex carbohydrates to satisfy dieters. High-fiber foods also slow absorption of carbohydrates, so they do not provoke a rapid rise in blood sugar and insulin.

TABLE 5.11
Low calorie, lower fat alternatives
Instead of …		Replace with …
SOURCE: "Appendix C. Instead of … Replace with …" in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12,2006)
Evaporated whole milk Whole milk Ice cream Whipping Cream Sour cream Cream cheese Cheese (cheddar, Swiss, jack) American cheese Regular (4%) cottage cheese Whole milk mozzarella cheese Whole milk ricotta cheese Coffee cream (half and half) or nondairy creamer (liquid, power)	Dairy products	Evaporated fat free (skim) or reduced fat (%2) milk Low fat (%1), reduced fat (2%), or fat free (skim) milk Sorbet, sherbet, lowfat or fat free frozen yogurt, or ice milk (check label for calorie content) Imitation whipped cream (made with fat free [skim] milk) or lowfat vanilla yogurt Plain lowfat yogurt Neufchatel or "light" cream cheese or fat free cream cheese Reduced calorie cheese, low calorie processed cheese, etc. Fat free cheese Fat free American cheese or other types of fat free cheeses Lowfat (1%) or reduced fat (2%) cottage cheese Part skim low-moisture mozzarella cheese Part skim milk ricotta cheese Low fat (1%) or reduced fat (2%) milk or nonfat dry milk power
Ramen noodles Pasta with white sauce (alfredo) Pasta with cheese sauce Granola	Cereals, grains and pasta	Rice or noodles (spaghetti, macaroni, etc.) Pasta with red sauce (marinara) Pasta with vegetables (primavera) Bran flakes, crispy rice, etc. Cooked grits or oatmeal Whole grains (e.g., couscous, barley, bulgur, etc.) Reduced fat granola
Cold cuts or lunch: meats (bologna, salami, liverwurst, etc.) Hot dogs (regular) Bacon or sausage Regular ground beef Chicken or turkey with skin, duck, or goose Oil-packed tuna Beef (chunk, rib, brisket) Pork (spareribs, untrimmed loin) Frozen breaded fish or fried fish (homemade or commercial) Whole eggs Frozen TV dinners (containing more than 13 gram of fat per serving) Chorizo sausage Croissants, brioches, etc. Donuts, sweet rolls, muffins, scones, or pastries Party crackers Saltine or soda crackers (Choose lower in sodium) Cake (pound, chocolate, yellow) Cookies	Meat, fish, and poultry	Lowfat cold cuts (95% to 97% fat free lunch meats, lowfat pressed meats) Lower fat hot dogs Canadian bacon or lean ham Extra lean ground beef such as ground round or ground turkey (read labels) Chicken or turkey without skin (white meat) Water-packed tuna (rinse to reduce sodium content Beef (round, loin,) (trimmed of external fat) (choose select grades) Prok tenderloin or trimmed, lean smoked ham Fish or shellfish, unbreaded (fresh, frozen, canned in water) Egg whites or egg substitutes Frozen TV dinners (containing less than 13 grams of fat per serving and lower in sodium) Turkey sausage, drained well(read label) Vegetarian sausage (made with tofu) Hard French rolls or soft "brown 'n serve" rolls English muffins, bagels, reduced fat or fat free muffins or scones Low fat crackers (choose lower in sodium)
	Baked goods	Cake (angel food, white, gingerbread) Reduced fat or fat free cookies (graham crackers, ginger snaps, fig bars) (compare calorie level)
Nuts Ice cream. e.g., cones or bars Custards or puddings (made with whole milk)	Snacks and sweets	Popcern (air-popped or light microwave), fruits, vegetables Frozen yogurt, frozen fruit, or chocolate pudding bars Puddings (made with skim milk)
Regular margarine or butter Regular mayonnaise Regular salad dressings Butter or margarine on toast or bread Oil shortening, or lard	Fats, oils, and salad dressings	Light-spread margarines, diet margarine, or whipped butter, tub or squeeze bottle Light or diet mayonnaise or mustard Reduced calorie or fat free salad dressing, lemon juice, or plain, herb-flavored, or wine vinegar Jelly, jam, or honey on bread or toast Nonstick cooking spray for stir-frying or sautéing As a substitute for oil or butter, use applesauce or prune puree in baked goods
Canned cream soups Canned beans and franks Gravy (homemade with fat and/or milk) Fudge sauce Avocado on sandwiches Guacamole dip or refried beans with lard	Miscellaneous	Canned broth-based soups Canned baked beans in tomato sauce Gravy mixes made with water or homemade with the fat skimmed off and fat free milk included Chocolate syrup Cucumber slices or lettuce leaves Salsa

Table 5.11 shows some of the food substitutions that may be made to reduce the dietary fat content. In addition to making substitutions, many fat-free or low-fat food products are available—from fat-free frozen desserts to TABLE 5.12 Fat free or reduced fat versus regular "Fat Free or Reduced Fat Versus Regular," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)reduced-fat peanut butter. However, dieters are often cautioned that fat-free or reduced-fat foods are not calorie-free, and their consumption will not result in weight loss when more of the reduced-fat foods are consumed than would be eaten of the full-fat versions. For example, eating twice as many baked tortilla chips would actually result in higher caloric intake than a single serving of regular tortilla chips. (See Table 5.12.)

TABLE 5.12
Fat free or reduced fat versus regular
Fat free or reduced fat	Calories	Regular	Calories
SOURCE: "Fat Free or Reduced Fat Versus Regular," in The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, National Institutes of Health, National Heart, Lung, and Blood Institute, North American Association for the Study of Obesity, October 2000, http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm (accessed January 12, 2006)
Reduced fat peanut butter, 2 T	187	Regular peanut butter, 2 T	191
Cookies		Cookies
Reduced fat chocolate chip cookies, 3 cookies (30 g)	118	Regular chocolate chip cookies, 3 cookies (30 g)	142
Fat free fig cookies, 2 cookies (30 g)	102	Regular fig cookies, 2 cookies (30 g)	111
Ice creams		Ice cream
Nonfat vanilla frozen yogurt (1% fat), 1/2 cup	100	Regular whole milk vanilla frozen yogurt (3-4% fat), 1/2 cup	104
Light vanilla ice cream (7% fat), 1/2 cup	111	Regular vanilla ice cream(11% fat), 1/2 cup	133
Fat free caramel topping, 2 T	103	Caramel topping, homemade with butter, 2 T	103
Low fat granola cereal, approx, 1/2 cup (55 g)	213	Regular granola cereal, approx, 1/2 cup (55 g)	257
Low fat blueberry muffin, 1 small (2 1/2 inch)	131	Regular blueberry muffin, 1 small (2 1/2 inch)	138
Baked tortilla chips, 1 oz	113	Regular tortilla chips, 1 oz.	143
Low fat cereal bar, 1 bar (1.3 oz.)	130	Regular cereal bar, 1 bar (1.3 oz.)	140

Low-Fat versus Low-Carbohydrate Diets

In the absence of rigorous scientific research and studies demonstrating the long-term safety and effectiveness of low-carbohydrate and low-fat diets, many investigators and health professionals hesitate to proclaim one diet's superiority over all others. There is general consensus that while some diets may produce greater initial weight loss, most perform similarly over time.

In "Efficacy and Safety of Low-Carbohydrate Diets: A Systematic Review" (Journal of the American Medical Association, vol. 289, no. 14, April 2003), Dena Bravata and her colleagues from Stanford and Yale Universities reported the results of their analysis of data about diet-induced changes in weight, serum lipids, fasting serum glucose and fasting serum insulin levels, and blood pressure among adults using low-carbohydrate diets. The investigators stated that they undertook the research in response to concerns about low carbohydrates expressed by the American Dietetic Association (ADA) and the American Heart Association (AHA). Both organizations had warned that low-carbohydrate diets may lead to abnormal metabolic functioning that in turn may prompt serious medical consequences, particularly for participants with cardiovascular disease, Type 2 diabetes mellitus, hyperlipidemia, or hypertension. Specifically, it has been cautioned that low-carbohydrate diets cause the accumulation of ketones, which may result in abnormal metabolism of insulin, impaired liver and kidney function, and salt and water depletion that may cause postural hypotension (sudden drop in blood pressure when rising from sitting) as well as fatigue, constipation, and kidney stones. It has also been posited that excessive consumption of animal proteins and fats may promote hyperlipidemia, and that higher dietary protein loads that may impair kidney function.

Not surprisingly, the investigators found that diets that restricted calorie intake and were longer in duration were associated with weight loss. They also observed that when lower-carbohydrate diets resulted in weight loss, it was likely due to the restriction of calorie intake and longer duration rather than changes in carbohydrate intake. The investigators did, however, observe that at least in the short term, low-carbohydrate diets were not associated with the anticipated adverse effects on lipid levels, glucose levels, or blood pressure. Further, their findings suggested that people without diabetes tolerated a lower-carbohydrate diet better than higher-carbohydrate alternatives and that this diet may be an effective means of achieving short-term weight loss without significant adverse effects on serum lipid levels, glycemic control, or blood pressure. They cautioned, however, that there is still inadequate evidence to recommend or condemn the use of low-carbohydrate diets among people with diabetes or for long-term use.

Michael Dansinger and his colleagues at Tufts University, New England Medical Center, compared the effectiveness of four popular diets—Atkins (low carbohydrates), the Zone (moderate carbohydrates), Ornish (low-fat vegetarian), and Weight Watchers (moderate fat). They presented the results of their study, funded by a National Institutes of Health (NIH) grant, the Tufts-New England Medical Center, and the USDA Nutrition Research Center at Tufts, at the scientific sessions of the American Heart Association meeting in November 2003.

Study participants were asked to follow the diets they were given as best they could for two months, and they were given official diet cookbooks and assigned to small group classes for diet education. For the remaining ten months the participants were told to follow their assigned diets "to whatever extent they wanted." The investigators reported that nearly one-quarter of the participants (22%) had dropped out of each diet after just two months, and by twelve months half of the participants assigned to low-carbohydrate or low-fat vegetarian diets had dropped out, as had 35% of participants assigned to the moderate carbohydrates and moderate fat diets. For those participants who adhered, weight loss and reduction in cardiac risk scores as measured by reductions in low-density lipoprotein (LDL cholesterol) and insulin levels were comparable for participants on the low-carbohydrate, moderate-carbohydrate, and moderate-fat plans. According to the study, the Ornish diet (low-fat vegetarian) "was best for lowering 'bad' LDL cholesterol, while other diets were better at raising 'good' HDL cholesterol."

The investigators concluded that their research "demonstrated that all these diets work." They also reiterated the importance of tailoring the selection of a weight-loss diet to ensure adherence, asserting "That means that physicians can work with patients to select the diet that is best suited to the patient. For example, if you have a patient who likes meat, it is unlikely that he or she will comply with the Ornish diet" (American Heart Association Scientific Sessions, Abstract 3535, November 12, 2003).

In "Low-Carb, Low-Fat Diet Gurus Face Off" (Journal of the American Medical Association, vol. 289, no. 14, April 2003), author Joan Stephenson asked the champions of the opposing regimens to offer their opinions about weight-loss approaches and the obesity epidemic. The late Dr. Atkins observed that low-carbohydrate dieters experienced more weight loss and greater improvements in LDL cholesterol and HDL than people on low-fat diets. He explained that while people on his plan consume about 40% of their calories from fat, as opposed to the U.S. average of 30%, the increased fat consumption is not harmful because "When the carbohydrate content is low, the fat takes a different metabolic pathway and forms energy through ketones, which then gets burned up right away. So the ketones do not accumulate because they're being used for energy."

In the same article, Dr. Ornish asserted that the overall health benefits of a low-fat diet were greater because carbohydrates are less calorie dense than protein and fat and that this diet sharply limits consumption of disease-promoting substances such as saturated fat and dietary cholesterol while increasing intake of protective nutrients such as phytochemicals, carotenoids, and lycopene—substances found in fruits, vegetables, grains, beans, and soy products. Ornish also observed that while there is not yet any data indicating that low-carbohydrate diets can reverse coronary heart disease, low-fat diets have been found to not only produce weight loss but also to reverse heart disease as measured by quantitative arteriography (systematic examination of the arteries using an injected contrast material that can be seen using x-ray equipment) and other cardiac imaging studies.

In May 2004, two published studies reaffirmed the safety and efficacy of low-carbohydrate diets. In the first study, 120 study participants were assigned to a low-carbohydrate, high-protein diet or a low-fat, low-cholesterol, low-calorie diet. The low-carbohydrate group was allowed unlimited calories, animal foods (meat, fowl, fish, and shellfish), and eggs, as well as 4 ounces of hard cheese, two cups of salad vegetables (lettuce, spinach, or celery) and one cup of low-carbohydrate vegetables (broccoli, cauliflower, or squash). The low-fat, low-cholesterol, low-calorie group consumed less than 30% of daily caloric intake from fat, less than 10% of calories from saturated fat, and less than 300 mg cholesterol daily. After six months, weight loss was greater in the low-carbohydrate diet group than in the low-fat diet group. Compared with the low-fat diet group, the low-carbohydrate diet group had greater decreases in serum triglyceride levels and greater increases in HDL cholesterol levels (William Yancy Jr. et al., "A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet to Treat Obesity and Hyperlipidemia: A Randomized, Controlled Trial," Annals of Internal Medicine, vol. 140, no. 10, May 18, 2004).

In the second study, researchers assigned 132 obese adults to either restrict carbohydrate intake to less than 30 g per day (low-carbohydrate diet) or to restrict caloric intake by 500 calories per day with less than 30% of calories from fat (conventional diet). After one year, weight loss was greater in the low-carbohydrate diet group, and the researchers found that the low-carbohydrate diet group fared better in terms of greater decrease in triglyceride levels (Linda Stern et al., "A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet to Treat Obesity and Hyperlipidemia: A Randomized, Controlled Trial," Annals of Internal Medicine, vol. 140, no. 10, May 18, 2004).

In October 2004 yet another study confirmed that modified low carbohydrate diets produced greater weight loss than the U.S. National Cholesterol Education Program (NCEP) diet, which replaces saturated fat with carbohydrates (Y. W. Aude et al., "The National Cholesterol Education Program Diet vs. a Diet Lower in Carbohydrates and Higher in Protein and Monounsaturated Fat: A Randomized Trial," Archives of Internal Medicine, vol. 164, no. 19, October 25, 2004).

The following month, however, Suzanne Phelan, a researcher from Brown Medical School asserted that low-fat diets produce better long-term weight loss than low-carbohydrate diets at a meeting of the North American Association for the Study of Obesity. She and her colleagues studied 2,700 people who entered the National Weight Control Registry, which records successful efforts to lose at least thirty pounds and maintain the loss for at least one year. All of the subjects reported eating about 1,400 calories a day, but the portion derived from fat rose from 24% in 1995 to more than 29% in 2003, while the portion from carbohydrates fell, from 56% to 49% The number who were on low-carbohydrate diets (less than 90 grams a day) rose from 6% to 17% during the same period.

Although the type of diet—low-fat or low-carbohydrate—made no difference in how people lost weight initially, those who increased their fat intake over a year regained the most weight. The researchers concluded that they ate fewer carbohydrates, since the amount of protein in their diets remained the same. The researchers concluded that the minority of successful dieters use low-carbohydrate regimes.

While there is no single winner in the diet wars, further research has dispelled some fears about the safety and effectiveness of the low-carbohydrate diet. Low-carbohydrate diets appear to be safe and effective in the short term, but long-term outcomes still are unclear. Although some results suggest that higher protein and fat intakes lead to lower total caloric intake by producing earlier satiety, these diets have not been shown to alter fundamental eating behaviors nor have they demonstrated, as many of their proponents argue, the ability to modify caloric balance such that weight loss persists when more calories are consumed than expended.

Finally, research published in the Journal of the American Medical Association in January 2005 asserted that adherence to a diet for one year, rather than the specific type of diet, is the single most important determinant of weight loss and reduction of risk of cardiovascular disease. The investigators found the amount of weight lost was associated with the level of dietary adherence but not with diet type, and they concluded that, "One way to improve dietary adherence rates in clinical practice may be to use a broad spectrum of diet options, to better match individual patient food preferences, lifestyles, and cardiovascular risk profiles. Our findings challenge the concept that one type of diet is best for everybody and that alternative diets can be disregarded. Likewise, our findings do not support the notion that very low carbohydrate diets are better than standard diets, despite recent evidence to the contrary" (Michael Dansinger et al., "Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction: A Randomized Trial," Journal of the American Medical Association, vol. 293, no.1, January 5, 2005).

In an accompanying editorial, Robert H. Eckel, a physician from the University of Colorado at Denver, commented that, "It seems plausible that for maintenance of reduced body mass, the right diet needs to be matched with the right patient" He advised a "low fad" approach for people dieting to lose weight ("The Dietary Approach to Obesity: Is It the Diet or the Disorder?" Journal of the American Medical Association, vol. 293, no.1, January 5, 2005).