Here’s how to fine-tune your workouts and eating habits to shed those pounds—and keep ’em off.  Exercise at least 4 hours a week. That amount helped nearly 44,000 women in their 40s or early 50s achieve weight loss instead of weight gain during a 10-year American Cancer Society study.  Crank it up for 10 minutes a day. In a Kaiser Permanente study, a similar group of women who exercised vigorously (like jogging) for 10 or more minutes a day had waistlines nearly 6 inches smaller than women who didn’t raise their heart rates that high. Lift weights. Two or three sessions a week can help stave off age-related muscle loss, which slows your metabolism. Skip the refined carbs. Women whose diets were high in whole grains and fiber gained less weight than those who ate more sugar and white flour, reports a Danish study.  More from Prevention: 100 Simple Ways To Lose Weight