Updated: 11:42 AM EST Jan 21, 2021 Meghan Rabbitt Contributor There s no reason you can t look as fit and fabulous at 50 as you did at 40.But there is one hitch: Even stars with personal trainers and nutrition coaches have to work a little harder to lose the pounds once they hit this milestone age.One of the main reasons you ll have to put in extra effort: Your body composition changes as you age. You lose muscle mass at an average rate of 3-5% for every 10 years after age 35, and this can impact the way you burn fat. “Your body goes into its aging stage as it leaves the growing one,” says Dr. Luiza Petre, a New York City-based weight loss and management specialist, and assistant clinical professor of cardiology at the Mount Sinai School of Medicine. “When this happens, your body doesn’t need as much energy as it used to,” she explains. Why it s harder to lose weight after 50What s more, all those years of playing sports, running after your k