If your jeans don’t button quite as easily as they used to and your shirts feel extra snug these days, you’re not alone: Thousands of older folks struggle with weight gain when they retire. So, is retirement making you fat?At a time when out-of-pocket medical costs have been steadily rising for seniors, it’s a question that’s just as important to financial well-being as to physical health. And it’s possible that retirement is connected to adding extra pounds, according to several recent studies.A study from the Institute for Health Policy Studies titled "The Effect of Retirement on Weight,” for example, studied a group of almost 38,000 retirees and concluded that retirement is connected to "modest weight gain.” The study focused on "body mass index,” or BMI, which is calculated by dividing a person’s weight by his or her height. The researchers found that the average person added .24 to their body mass index upon retirement.That’s not a huge amount -- typically 2 to 4 pounds. But other research suggested that some subgroups of retirees were more vulnerable. In a separate study, women who retired were more likely to gain weight than their same-age working counterparts. A third study found that men who retired from physically demanding jobs were more likely than others to gain weight within six years.So what’s the explanation for these extra pounds? Some of the weight gain may be due to the fact that many people are less physically active when they retire, and that they have less structured meal times or change their eating patterns in retirement, according to a study from the University of Iowa College of Medicine. And some of it has less to do with retirement per se than with the aging process. Our metabolisms slow as we age, explains Desmond Ebanks, a doctor and founder of Alternity Healthcare, a medical practice that focuses on older patients. In fact, "we have to give up about 5% of the amount of calories we are eating every decade after 40 if we want to prevent weight gain,” estimates fitness and lifestyle coach Rona Lewis, author of "Does This Cookbook Make Me Look Fat?”This weight gain can do more than just impact your body image -- it can cost you, big. "There is no question that being obese or overweight is more costly than being of normal weight,” write the authors of "A Heavy Burden: The Individual Costs of Being Overweight and Obese in the United States,” a 2010 study from researchers at George Washington University’s School of Public Health and Health Services. In fact, the study showed that each year, morbidly obese people pay $2,845 more in medical costs than their normal-weight counterparts; severely obese, $1,566; moderately obese, $807; and overweight, $346.The good news: "Weight gain does not have to be a part of retirement,” says Carmella Sebastian, a doctor and the senior medical director of clinical client solutions for Blue Cross and Blue Shield of Florida. Here are five things you can do to keep yourself slim and trim -- and potentially save money.Eat better. It sounds like a no-brainer, of course, but it’s particularly important for retirees -- some of whom begin to eat out more or snack out of boredom, leading to weight gain, says registered dietician Lisa Hugh, who specializes in nutrition therapy. Ebanks recommends that retirees try to stay away from many packaged foods; avoid excess refined carbs (think white flour, sweetened drinks, and any form of table sugar); eat more fruits, veggies and whole grains; and make sure they get adequate protein. Exercise more. Exercise is important to losing weight, but seniors need to do more than just cardio. "Muscle is more efficient, so weight-lifting -- even small weights -- will increase muscle mass and hence, your metabolism,” Hugh says.Get enough sleep. "Inadequate sleep can lead to weight gain,” says Ebanks, who recommends trying to get seven to nine hours of sleep a night.Manage stress. Retirement often comes with a lot of changes, and these can cause stress -- which in turn can mean weight gain due to "stress eating” and hormonal changes associated with stress. Effective stress-management techniques include exercise and meditation, experts say.Get your blood work done. Sometimes, something more serious than a lifestyle change can be causing the extra pounds. "Get your blood work checked and in particular, your thyroid function,” says Sebastian. The thyroid has an impact on metabolism, she explains, so a malfunctioning gland can lead to weight gain -- a problem you could address with a thyroid supplement.Agencies