The study, which was carried out by a multi-disciplinary team of researchers and published in the online journal PLoS ONE, investigated the ‘protein leverage hypothesis’. This suggests that protein plays an important role in determining overall energy intake and thus affects obesity.
Researchers tested 16 female and six male participants, who each spent three four-day periods on different diets, designed to be similar in palatability, availability, variety and sensory quality, but with different levels of protein. Energy intake and appetites were measured throughout the study period.
The scientists found that when subjects were fed a 10% protein diet, they consumed 12% more energy over the four days then they did on a 15% protein diet. Moreover, 70% of the increased energy intake on the lower-protein diet was attributed to snacking.
Co-author Susan Jebb, head of diet and population at the the Medical Research Council Human Nutrition Research unit (HNR) in Cambridge, UK told meatinfo.co.uk that protein intakes are currently close to 15%, which is actually higher then what is required to prevent protein deficiency.
However, she said the study showed that when this protein is ‘diluted’ by carbohydrate and fat, people tend to increase their total energy intake (calories), putting them at greater risk of obesity. “Interestingly the main change in eating habits was an increase in snack intake between meals on the lower protein diet,” she said.
Jebb added that it would be hard to draw specific dietary advice for the public from this one study, but said the research supported the notion that maintaining or modestly increasing the proportion of energy derived from protein can help prevent weight gain.
“This might be achieved by consumers shifting the proportion of food on the plate or may encourage food manufacturers to consider ways to boost the proportion of protein in food – whether main meals or snacks to help boost satiety,” she said. “This may be by increasing the amount of meat/fish etc or by constraining the calories added from carbohydrate or fat.