Question: How can I gain muscle while I am on a low-kilojule diet to lose weight?  

Answer: 
Sorry bud, there’s no magic trick for this—just reality. “Chances are you won’t gain muscle while on a very-low-kilojule diet,” says Mike Roussell, Ph.D., a Men’s Health nutrition advisor. While it’s possible to gain muscle and lose weight, the lower your kilojules are, the more likely you are to lose muscle. “To boost the likelihood of gaining muscle at the same time you lose weight, put the emphasis on increasing the amount of kilojules you’re burning during exercise more than reducing how many calories you eat,” Roussell says.

Instead of focusing on less when it comes to your kilojule intake, think about more when it comes to how much protein you’re eating. Researchers at the U.S. Army Research Institute of Environmental Medicine found that when participants followed a reduced-kilojule diet (in which they slashed kiljojules by 40 percent) exercised daily, and ate twice the recommended daily amount (RDA) of protein, they lost just as much weight, but shed more fat and maintained more muscle mass than participants who ate the same number of calories, but consumed the RDA of protein. The RDA is .8 grams of protein per kilograms of bodyweight per day. For an 81 kilogram guy, the RDA is about 65 grams; twice that amount is 130 grams.