If you’ve been working out seven days a week and eating clean, but still not dropping pounds, you may be spending your time at the gym all wrong. “If your primary goal is weight loss, I’d focus your exercise efforts on light cardio,” says nutrition scientist and exercise physiologist David Plourdé, Ph.D., CEO and founder of the Plourdé Institute in Lisle, IL. “More vigorous exertion causes muscle fibers to switch to glucose utilization,” which means your body won’t kick into fat-burning mode, he explains. “With a really vigorous workout you may perceive that you’re being productive, because you sweat more and it’s a lot of work, but our lab tests reveal a very different outcome. ”Plourdé also suggests getting tested in a Bod Pod (above)—a machine found at high-end gyms and sports medicine clinics—which measures your fat and lean tissue by air displacement plethysmography technology (ADP). A trained fitness or health care professional can then review your results and design a program to help you achieve your goals.