What boosts body fat?

People who eat too much of a high-calorie, low-protein diet tend to gain more body fat than people who overeat high amounts of protein, US researchers said.

Calories are more important than protein while consuming excess amounts of energy...

They studied 25 people in Louisiana who agreed to live as in-patients in a weight-gain experiment for a 56-day period.

Over the course of about two months, they were overfed by about 1,000 calories per day.

Some were fed a diet that was five per cent protein, some ate 15 per cent protein – considered a normal level – and others ate 25 per cent protein, or a high amount.

The researchers said in the Journal of the American Medical Association that their aim was to uncover how different levels of protein might affect overall weight gain, body fat and energy expenditure.

They found that people on the low-protein diet gained less weight overall, but that more of their extra energy was stored as fat than people on the mid-level and high-protein diets.

Low-protein eaters gained about half as much as the others – putting on an average of 3.16 kilograms during the study compared to 6.05 kg in the normal protein group and 6.51 kg in the high-protein group.

But a lot of that extra weight was in the form of lean body mass, which people on the mid- and high-level protein diets gained while those on the low-protein regime lost.

Ninety per cent of the extra energy consumed by people on the low-protein diet was stored as fat, compared to about 50 per cent in the other two groups.

“The key finding of this study is that calories are more important than protein while consuming excess amounts of energy with respect to increases in body fat,” said the research, led by George Bray of the Pennington Biomedical Research Centre in Baton Rouge, Louisiana.