The 3 most popular diets: Is one right for you?

by Jeff S. Volek, Ph.D., R.D.

As we all know, there are many popular diets promoted to the public, and in many cases the diets are polar opposite in terms of the foods they recommend. There is no better example of this than the diets promoted by Dr. Robert Atkins (an ultra low carbohydrate/high-fat approach) and Dr. Dean Ornish (an ultra high-carbohydrate/low-fat approach). In the middle, there is the more moderate research-based approach outlined by Dr. Willet at the Harvard School of Public Health. This makes for a pretty confusing message to consumers, but indeed there is some scientific basis for each of these diets. Below is a brief description of each diet and some of the potential advantages and disadvantages associated with each diet plan.

Atkins Diet: Low Carb - "Dr. Atkins' Diet Revolution"

The cornerstone of the Atkins philosophy is controlling carbohydrate intake. The diet involves a 4-phase eating plan in conjunction with vitamin and mineral supplementation and regular exercise. The idea initially is to limit carbohydrates to a very low level (less than 20 grams a day). This forces the body to use its own fat stores for fuel and produces ketones because carbohydrate availability is low. Gradually more carbohydrates are allowed during ongoing weight loss and weight-maintenance phases. An estimated 20 million people worldwide have embraced this diet philosophy since the 1970s.

Willet Diet: Medium Carb - "Eat, Drink, and Be Healthy"

This diet is based on much of the epidemiology work done by Dr. Willet and his colleagues at the Harvard School of Public Health and reflects the latest research on optimal diet for health. Different from the original and flawed food guide pyramid, the healthy eating pyramid advocated by this group emphasizes physical activity and weight control at the base of the pyramid and foods such as whole grain foods, vegetable oils (especially Omega-3 fatty acids), and fruits and vegetables. Nuts and legumes are given their own category and encouraged. Refined grains (white bread and white rice), red meat, and dairy products are de-emphasized.

Ornish Diet: High Carb - "Eat More Weigh Less"

The Ornish diet is based on the notion that if you eat a very high high-carbohydrate/low-fat diet rich in fiber you can eat a greater amount of food than usual, and still lose body fat. The diet advocates extremely high fiber and carb intake, especially complex over simple carbs. There is some evidence the diet slows or even reverses the hardening of the arteries that can eventually trigger heart attacks. Protein sources come from egg whites and nonfat dairy or soy products. Smaller amounts of protein are obtained from fiber-rich plant-based sources (vegetables, whole grains, beans). Fish is discouraged, despite significant research showing beneficial effects.

ATKINS
DIET CHART

WILLET
DIET CHART

ORNISH
DIET CHART

Calories from Nutrients:
Protein: 25% +
Carbs: 10%
Fat: 65%

Calories from Nutrients:
Protein: 15%
Carbs: 50%
Fat: 35%

Calories from Nutrients:
Protein: 15%
Carbs: 75%
Fat: 10%

Potential Advantages

	Decreases appetite, which could enhance compliance during low-calorie dieting
	Results in rapid weight loss, which is motivating initially
	Many fatty foods typically not recommended can be eaten
	Moderate to large decreases in triglycerides
	Small to moderate increases in protective HDL (good) cholesterol
	Increases size of LDL (bad) cholesterol particles making them less likely to form plaque
	Reduces insulin levels and normalizes blood sugar

Potential Disadvantages

	Many foods people are used to eating must be eliminated or consumed sparingly
	Potential for bad breath if ketosis is large
	May increase uric acid
	Much less scientific research (but the work that has been done is promising)

Potential Advantages

	Lowers total cholesterol, LDL (bad) cholesterol, and triglycerides
	Can increase HDL (good) cholesterol
	Reduces insulin levels and normalizes blood sugar

Potential Disadvantages

	Including large amounts of vegetable oils can be difficult to incorporate into the diet
	Limits on red meat and dairy could result in sub-optimal intakes of iron, zinc, and/or calcium if not provided in supplement form
	High quality protein sources are limited, which may affect protein status in physically active people

Potential Advantages

	Lowers total cholesterol and LDL (bad) cholesterol
	May slow down or reverse arterial plaque formation if combined with exercise and weight loss
	Reduces appetite due to high-fiber foods and therefore can assist weight loss

Potential Disadvantages

	Limits on consumption of meat and dairy products
	Limits healthy unsaturated fat
	Extreme nature makes long-term compliance unlikely
	Can raise triglycerides and lower HDL (good) cholesterol if not countered by exercise and/or weight loss
	Decreases the size of LDL (bad) cholesterol particles, making them potentially more likely to cause plaque formation in arteries

My Recommendations

From the clinical studies and research I've conducted, I can make these recommendations:

Find a diet to lose weight - those above will work. I prefer the Atkins diet or a modified-Atkins diet, minus the chemical-processed meats, like bacon, which are high in saturated fat.
To maintain a diet, be reasonable in your approach. All the diets require some sacrifice and attention to what you eat.
Protein: Concentrate on lean protein sources.
Eat complex carbs and high-fiber carbs, and avoid sugars. Adjust carb consumption to lose weight.
All diets require you to eat fat - I recommend you de-emphasize the saturated fats in dairy and meat, and consume vegetable fats like olive and flaxseed oil.
Regardless of which diet you follow, I recommend regular physical activity, weight control, and use of a daily multi-vitamin/mineral tablet.

Selected Sources

Dr. Atkins' New Diet Revolution, Robert Atkins. Avon, 2001.
Eat More, Weigh Less: Dr. Dean Ornish's Life Choice Program for Losing Weight Safely While Eating Abundantly. Dean Ornish, Shirley Elizabeth Brown. Quill, 2000.
Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating. Walter Willett, P.J. Skerrett, Maureen Callahan. Simon & Schuster, 2001.

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