American Institute for Cancer Research

The Low-Carb, High-Protein Craze

American Institute for Cancer Research Newsletter 67(2000):11.
American Institute for Cancer Research

Since its founding in 1982, the American Institute for Cancer Research has grown into the nation’s leading charity in the field of diet, nutrition and cancer.

A NUMBER OF FAD DIET BOOKS, including Sugar Busters, The Zone, Dr. Atkms New Diet Revolution and The Mayo Clinic Diet (not affiliated with the prestigious medical clinic in any way), are sweeping the country. Most fads are short-lived, but the low- carb, high-protein craze shows no signs of fizzling. This article, the third in a four-part series on managing your weight sensibly, asks an important question: Do these diets have any legitimacy?

The Theory Behind the Fad

These fad diet books focus on blood sugar levels. Sugar in the blood signals the pancreas to release insulin. This hormone sends sugar to the brain and muscles to be burned for energy. Extra sugar is stored for later use. Some of this storage is in the form of fat. A sudden rise in blood sugar means more insulin gets secreted and more sugar may be stored as fat. A slow, steady rise in blood sugar, on the other hand, meets your body’s en¬ ergy needs over time. And less sugar gets stored.

Carbohydrates raise blood sugar levels. Protein and fat have less effect on blood sugar. So, the authors of these fad diet books argue that the best way to lose weight is to skip eating carbs altogether. They believe that by filling up on protein and fat, a rise in blood sugar and increase in fat storage is avoided. But it’s not as simple as that. Not all carbs act the same way. Eating a plate of plain white rice will drive up blood sugar fast. But brown rice or other whole grains, which have more fiber, raise sugar levels more slowly. Even the sugar-raising effect of refined carbs like white rice or white bread is slowed when they are eaten with high-fiber vegetables, a small amount of cooking oil or proteins such as tofu, poultry or fish. In fact, any high-carbohydrate food eaten as part of a balanced meal will contribute to a slow, steady rise in blood sugar. So carbohydrates are not the villains the fad diets make them out to be. Nor will diets that limit or eliminate all foods containing carbs cause permanent weight loss.

Why Low-Carb Diets Fail

At first, low-carb diets seem to work. By limiting the foods you eat, they limit the calories you take in. Al¬ most immediately, water loss occurs. Then, when the body does not have a supply of carbohydrates for en¬ ergy, the liver begins making sugar out of whatever protein it can find-including your own muscles. The loss of water and muscle means your weight drops. But this kind of weight loss is temporary. Long-term weight control involves losing fat and keeping your muscles because muscle burns calories. Furthermore, this tem¬ porary weight loss is achieved at a high cost. Low-carb, high-protein diets can lead to irritability, light- headedness, bad breath, constipation, dehydration and kidney problems. Those are the short-term effects. The long-term effects are even more dire. Lovv-carb, high-protein diets call for limiting just those foods that contain the anti- oxidants and phytochemicals that tight cancer and other chronic diseases. At the same time, they encourage taking a second helping of foods laden with the kind of fat that promotes disease. Such a diet goes against the advice of all the health authorities. When you pass up carbohydrates and load up on pro¬ tein and fats, you increase your risk for heart disease, stroke and cancer.

A Diet You Can Live With

AICR’s Diet and Health Guidelines call for eating a variety of vegetables, fruits, whole grains and beans. These high-carbohydrate foods should push the pro¬ tein and fat from animal sources to the side of your plate. Following a mostly plant-based diet and exer¬ cising regularly can help you slowly lose weight with¬ out undermining your health.