High protein diets have no proven effectiveness in long-term weight reduction and post potential health threats for those who adhere to them for more than a short time, accordinhg to an advisory from the American Heart Associantion's Nutrition Committee in Circulation published in: Journal of the American Heart Association.
Some of the diets increase fat intake and reduce nutritionally rich foods such as fruits and vegetables, which is not a good approach to meeting a person's long-term dietary needs, says Robert H. Eckel, of the Association's Nutrition Committee. Many of these diets fail to provide vitamins, minerals, fibre and other nutritional elements, in addition to their high fat content.
A compelling argument against following a high-protein diet, Eckel ssays, is that these diets have not been documented to deliver on their promise of sustained, long-term weight loss.The safety, credibility and effectiveness of the revised American Heart Association nutritional guidelines, on the other hand, are backed by scientific documentation, he adds.
Studies have consistently shown that successful, maintenance of weight loss occurs most often when people follow a nutritionally sound diet and increase physical activity to burn more calories than they consume, says Eckel, professor of medicine at the University of Colorado Health Science Centre in Denver.
Foods emphasised in some of these high-protein and similar diets are from animal sources that are rich in both protein and saturated fat such as meat and eggs.Meanwhile, some of the diets drastically limit consumption of high-carbohydrate foods such as cereals, grains, fruits, vegetabled and low-fat milk products, Eckel says.Eating large amounts of high-fat animal foods over a sustained period has been shown to increase the risk of coronary heart disease, diabetes, stroke and several types of cancer, he adds.
A diet high in complex carbohydrates that includes fruits, vegetables, non-fat dairy products and whole grains has been shown to reduce blood pressure, the statement continues.Limitation of these foods, which are rich in calcium, potassium and magnesium (nutrients associated with blood pressure reduction), may lessen the benefit of weight loss on blood pressure reduction. Although proteins are essential nutrients required to maintain the body's structure and proper function, most Americans already eat more protein than their bodies need, and excess dietary protein can, in itself, also increase health risks, he emphasises.
High-protein diets induce a quick drop in weight primarily through loss of body fluids caused by the diuretic effect of eliminating most carbohydrates, he explains. Glycogen, the form of sugar used by the body for energy, is lost from the muscles as well, sometimes causing fatigue. In general, some of these diets also induce ketosis, a metabolic condition associated with low blood levels of insulin and resulting when the body is deprived of dietary carbohydrates. Sustained ketosis also causes a loss of appetite, which may lead to lower total calorie intake.Some popular high-protein, low-carbohydrate diets limit carbohydrates to 10-20 g per day, which is one fifth of the minimum 100 grams per day that are necessary to prevent loss of muscle tissue.