Effective Weight Reduction

An effective weight reduction program includes a nutritionally adequate, reduced energy intake as well as an increase in physical activity. The loss of body fat is proportional to the energy deficit – no specific distribution of dietary protein, carbohydrate, and fat has been shown to promote more rapid weight loss than other distributions. When energy expenditure exceeds energy intake, weight loss will occur regardless of the macronutrient composition of the diet.

Carbohydrates and insulin don't cause obesity and insulin is not a "monster" hormone. What matters for weight loss is not carbohydrates and insulin, but calories. Body weight depends on calorie balance – how many calories are consumed compared to how many are expended. Eating a high percentage of calories from carbohydrate does not promote fat storage – a person must eat too many calories relative to energy needs. For some people, a very high carbohydrate diet can raise insulin levels, and high insulin levels increase the risk of heart disease. However, there is no good evidence that high insulin levels make people fat.

There's nothing magical about these high protein, low carbohydrate regimens – they're just low-calorie diets. People lose weight on these diets because of the caloric restriction – not because of what is supposedly happening to their insulin levels. For example, although Enter the Zone says "don't focus on calories," the Zone diet provides only 800 to 1200 kcal a day for the average person.

Although the books claim to make people thinner, they actually make long term compliance difficult and take the fun out of eating. Most professional health groups in the country recommend 55 to 60% calories as carbohydrate, 10-15% as protein, and 30% or less as fat.

Weight loss eating plans should meet the criteria for a "healthy diet," as defined by the 2000 Dietary Guidelines for Americans and the 2000 American Heart Association Dietary Guidelines. The low carbohydrate diets advocated by these books fail because they are too high in total fat and saturated fat (except for the Sugar Busters and Zone diets) and don't supply adequate dietary carbohydrate, vitamins, minerals, and fiber. Such diets are also contrary to the scientific evidence that consuming a diet rich in plant foods such as whole grains, fruits, vegetables, and beans helps to prevent many chronic diseases, including coronary heart disease and cancer.

Nutrition recommendations should be supported by scientific research that is double-blind, placebo-controlled, and published in peer-reviewed journals. These diet books, however, abound with unproven claims based on case histories, testimonials, and unpublished studies.

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