That study looked at how eating different levels of protein affected weight gain in people who ate more calories than they needed to keep their weight stable. It included 25 men and women aged 18 to 35 who were at a normal weight or slightly overweight. They ate low, normal or high protein diets for eight weeks. They were also overfed by almost a thousand calories daily.
According to study leader George A. Bray, M.D., of the Pennington Biomedical Research Center "Fat storage was exactly the same with all three levels of protein. That is, it was the calories that they ate that affected the body fat that they stored."
And he added, "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."
Researchers say participants eating the low protein diet gained a little less than half the weight of those on the normal and high protein diets.