Dr Atkins knew it, as did his dietary nemesis Dukan. If you want to feel full on fewer calories, eat a steak.
Now the largest analysis yet of the effect of protein on appetite has confirmed the dieting folklore: eating protein-rich foods rather than carbohydrates really does make you fuller.
Until now most investigations of the idea, which has formed part of the justification behind fad diets such as the Atkins and Paleo diets, have been in small studies. For a paper published in the Journal of the Academy of Nutrition and Dietetics, scientists combined the results of 28 studies involving almost 500 participants to see if the effect still held true.
These studies generally worked by presenting people with two different meals, one high in protein and the other not. So half the subjects might be given chicken, the other half pasta. Then they were asked at a set time after eating how full they felt.
Richard Mattes, a professor of nutrition science at the University of Purdue in Indiana, said they found that higher amounts of protein did increase feelings of fullness. He suggested, albeit cautiously, that people looking to eat fewer calories without needing more willpower could increase the protein in their diet.
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“Though this study did not specifically evaluate dieters, feeling fuller could help to reduce food intake, an important factor when dieting,” he said. “If these effects are sustained over the long term — and our study only looked at short-term effects — increased protein intake may aid in the loss or maintenance of body weight.”
Feelings of fullness are caused by a feedback loop when hormones in the gut are released that tell the body to stop eating. While the study could not look at the causes of the findings, other research has implied that protein helps to activate these hormones.
Even so, Professor Mattes said that overweight people should not consider protein to be the magic intervention that some diet books might imply. The study did not determine the ideal quantity in a diet or the best time to eat it and, he said, in any case there are many causes of obesity, not least psychological ones. “Feelings like hunger and fullness are not the only factors that influence intake. We often eat for other reasons. Anyone who has ever felt too full to finish their meal but has room for dessert knows this all too well.”