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Tuesday, 9 October, 2001, 00:12 GMT 01:12 UK
High protein diet warning
Meat counter
High protein diets often contain a lot of meat products
High-protein diets may pose a risk to health, leading nutrition experts have said.

The influential American Heart Association has issued a warning about the fashionable diets.

It says that there is no evidence that they are effective - and they might actually do more harm than good.

Many of these diets fail to provide essential vitamins, minerals, fibre and other nutritional elements

Professor Robert Eckel
The warning from the AHA's nutrition committee, published in association's journal Circulation, says that there is no proof that the diets help people to lose weight in the long term.

It also warns that they may pose health risks to people who stick with them for more than a short time.

Professor Robert Eckel, of the University of Colorado, who co-wrote the advice, said: "High-protein items may also be high in fat. 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.

"Many of these diets fail to provide essential vitamins, minerals, fibre and other nutritional elements, in addition to their high fat content."

Animal protein

A diet rich in animal protein, saturated fat and cholesterol raises harmful LDL cholesterol levels. This increases the risk of coronary heart disease, diabetes, stroke and several types of cancer.

In contrast, a diet high in complex carbohydrates that includes fruits, vegetables, non-fat dairy products and whole grains has been shown to reduce blood pressure.

Professor Eckel said quick weight-loss diets did not work for most people.

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.

The American Heart Association urges most adults to limit fat intake to no more than 30% of total daily calories, less than 10% of which should be saturated fat.

However, it would be impossible to reach these targets by following some of the high-protein diets.

Healthy function

The body needs proteins to maintain healthy function. However, a normal, balanced diet contains all the proteins the body needs.

Excess protein can increase the risk of ill health. For instance, it can exacerbate the symptoms of liver and kidney disease.

High-protein diets produce rapid weight loss by stimulating the loss of fluids from the body.

However, this is also associated with the loss of glycogen, a vital energy source, from the muscles. This can lead to fatigue.

Claire MacEvilly, a nutrition scientist from the British Nutrition Foundation, told BBC News Online that people who lived on a high protein diet with lower levels of other nutrients risked developing a condition known as ketosis.

"This is a fat-burning state that occurs during starvation, and can be quite dangerous".

The urea derived from the breakdown by the liver of protein puts a lot of pressure on the kidneys.

Ketosis can also cause the blood to become more acidic.

See also:

06 Sep 01 | Health
Men's diets risk their hearts
06 Aug 01 | Health
Web diet warning
02 May 01 | Health
Health risk of 'faddy diets'
04 Jun 01 | Health
Too much variety 'makes you fat'
29 May 01 | Health
People 'fool themselves on diet'
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