If you’ve been thinking your spartan dietary regimen should lead to more weight loss than your scale actually reflects, it’s time to rethink the whole deal.

You know you’re getting enough aerobic (read: fat-burning) exercise every day—or at least five days a week—so something else must be responsible for the lack of weight loss. And, strangely enough, it could be that you aren’t eating often enough. In our three-squares-a-day culture, it’s not always easy to think in terms of six smaller meals a day. “In European countries, people tend to eat smaller meals and move more than we do,” says Jeannie Patton, MS, a clinical exercise physiologist, American College of Sports Medicine–certified exercise specialist, and personal trainer certified by the American Council on Exercise.

“In my experience, people with weight problems are often meal skippers,” Patton says. “Women who don’t eat enough and who exercise two to three hours a day do not lose any weight because the body becomes more efficient at getting calories and storing them.” Patton says if you wait too long between meals, your metabolic rate will slow down. So rearrange your daily food intake schedule to include enough fuel to keep your metabolism high enough to keep burnin’.