The trial on almost 50 overweight women confirms previous studies showing that a high-protein diet can lead to greater fat loss than a low-calorie, high carbohydrate diet. Researchers have also demonstrated that when both regimes are combined with an exercise programme, the protein-rich diet is still more effective at reducing body fat.
Researchers say there's an added interactive effect when a protein-rich diet is combined with exercise and that the two work together to correct body composition and dieters lose more weight and fat, than muscle. For the study researchers recruited 48 women aged around 46 years with a body mass index of 33 kg/m(2) during weight loss. Half the women were asked to eat a protein-rich diet containing specific levels of leucine, one of the essential amino acids, for four months. The others were asked to follow a diet based on the US food guide pyramid, which contained higher amounts of carbohydrates.
Both groups consumed the same number of calories, but the first group substituted protein foods, like meat, dairy products, eggs, and nuts, for foods high in carbohydrates, such as breads, rice, cereal, pasta, and potatoes. Both diets showed good results , however it was seen that people on the higher-protein diet lost more weight. High-protein diets have been controversial as they counter the accepted weight-loss diet and there is little information on their impact on health over the long-term. But recent studies suggest that they may indeed work better than low-calorie, high-carbohydrate diets by increasing satiety and reducing fat mass.
In the study the subjects were also required to follow one of two different exercise programmes. The first involved walking two to three times a week, while the second group included five 30-minute walking sessions and two 30-minute weightlifting sessions per week. In both groups of dieters, the exercise helped spare lean muscle tissue and target fat loss. But, the protein-rich, high-exercise group, lost even more weight, and almost 100 per cent of the weight loss was fat, report the researchers. In the high-carbohydrate, high-exercise group, however, as much as 25 to 30 per cent of the weight lost was muscle. The protein-rich diet seems to be even more effective for people at higher risk of heart disease.
Thus researchers conclude that a protein-rich diet dramatically lowers triglycerides and has a statistically significant effect on trunk fat, both risk factors associated with heart disease as it contains a high level of leucine, the amino acid that works with insulin to stimulate protein synthesis in muscle.