Despite what the late Dr Robert Atkins believed, eating less meat is the way to lose weight, a major study has discovered.
Keen meat-eaters were found to gain far more weight than those who had less meat in their diet - even when they consumed the same number of calories.
The findings suggest that people should eat less meat to stay healthy and that overweight people could lose weight by removing meat from their diets.
This contradicts the claims of many celebrity-endorsed diets, such as that of Dr Atkins, that promote eating high levels of protein and low levels of carbohydrate to lose weight.
The results come from a major British research project that tracked the diets of hundreds of thousands of people in ten European countries.
The authors of the study, from Imperial College London, said their results 'do not support the theory that a high-protein diet prevents obesity or promoted weight-loss, contrary to what has been advocated'.
The research team examined data from the Epic study, which looks at links between diet and cancer.
While many studies have suggested eating a lot of meat can lead to weight gain, it was thought that these people were also prone to other unhealthy activities, such as smoking, drinking and not doing enough exercise.
The team from Imperial College analysed dietary questionnaires filled out by more than 100,000 men and 270,000 women and weights taken before and after the five-year study.
But the authors of the latest study say they have taken all these factors into account.
They found that for every additional 250g of meat a person ate daily - the equivalent of a half-pound, or 450-calorie, steak - they would gain 4.4lb more weight over a five-year period.