It may help trim the waistline, but if someone is pumping iron with the goal of growing bigger biceps, the fat-forward ketogenic diet may not be the way to go. Research published in the Journal of the International Society of Sports Nutrition found that following the low-carb keto diet helped strength-trained women ages 23–31 to drop fat mass with no significant loss of fat-free mass over a 2-month period.

That sounds like a win and a reason to go crazy for avocados. But the trendy diet, which was compared with a diet higher in carbohydrates, was also shown (through body composition measurements before and after the study period) to stymie participants’ ability to build new muscle mass. And only the higher-carb diet resulted in improvements in upper-body strength, including bench press performance.

One study limitation was that the keto group showed signs of not consuming enough calories to meet the overall energy needs of training. This could have hindered muscle and strength gains. So, if your clients want to gain muscle and strength, they may need to be educated on the potential pitfalls of following a restricted eating pattern, such as a low-carb diet.