There are basically 5 reasons it’s harder to lose weight with age: You’re losing muscle mass, but eating the same amount. Most people lose muscle mass as they age, and since muscle burns more calories than fat, unless you’re doing some strength training to build muscle, you’ll gain weight. Hormonal changes. For women, menopause causes estrogen loss and causes extra pounds to settle around your belly. For men, a drop in testosterone that comes with aging can mean the body is less effective in burning calories. Your metabolism slows down with age. And having more body fat and less muscle mass exacerbates the situation. You’re busier with work. This can mean you sit more at work and during your commute, you skip lunch and get a snack out of the vending machine more often, and you’re too tired when you get home to even think about exercise. In addition, work-related stress can cause you to eat more and drink more alcohol, leading to increased weight. You have major lifestyle changes. These changes can start as early as your 30s. For women, starting a family can be the beginning of a battle with weight. Suddenly, it seems as if all your time is devoted to your children and you don’t have that extra hour to work out. At least one study shows that for men, simply getting married can lead to weight gain, as can fatherhood.