“The beauty of your metabolism is that it can be manipulated,” writes self-proclaimed “metabolism whisperer” Haylie Pomroy in her book The Fast Metabolism Diet, which claims to “set your metabolism on fire.” “When we talk about metabolism, we’re talking about the calories you burn when you’re not doing anything, or your resting metabolism,” says Michael Jensen, director of the Obesity Specialty Council at the Mayo Clinic. “Unfortunately, we don’t have much control over our resting metabolism.”