Runners are not immune to midlife weight gain. In fact, the National Runners’ Health Study has shown that most runners gain half a pound to a pound per year during their thirties, forties, and fifties. That’s 50 percent less than the average weight gain of nonrunners during the same period, but it still adds up. After thirty years it could easily total twenty to thirty pounds.

The extra weight almost never does you any good. For one thing, it’s associated with higher risks for all the chronic lifestyle illnesses, from diabetes to heart disease. It’s also linked to higher incidences of cancers and to osteoarthritis of the knees and hips. Finally, the added pounds make you slower by about 2 seconds per pound per mile.

Aging makes you slower, and the extra pounds make you slower. That’s a double whammy. Who wouldn’t want to avoid half of it—the weight-gain half that you can control?

There is a bit of a silver lining here. If you continue running despite any gained weight, you will have substantial health advantages over nonexercisers of the same weight. (Actually, percentage of body fat is the real enemy. But you know your own body. You know if you’re getting fatter or not.) These advantages are called the “fat but fit” effect. The conclusion comes from multiple large-population studies that tracked subjects for many years. Those who were fat but fit, because they exercised regularly, lived longer than unfit subjects who actually weighed less. In other words, fitness limits many of the harms of fatness. So keep running, no matter what.

But don’t settle for your current weight if you’re carrying more body fat than you should. Lean and fit beats fat but fit, so why not aim for your healthiest and fastest weight? “It’s definitely good to be as fit as possible, no matter what your body weight,” says Harvard nutrition and health expert Walter Willett, MD. “But it’s also optimum to be lean. It shouldn’t be a question of one or the other.”

For the most part, losing weight depends on self-discipline. You’re a runner, so you’ve got plenty. You simply need to apply it to your food-consumption habits. Eat less first, then move more as an added bonus.

  

Make small changes that yield big results: You don’t lose weight by eliminating favorite but unhealthy foods from your diet. The cravings soon come back, and may very well overwhelm you. The more proven way to lose weight is to change habits. Change yourself.

There are many ways to do this. If you apply 15 minutes of self-control at the supermarket, you’ll return home without that bag of cookies that tempts you every afternoon. If a particular restaurant serves a high-calorie meal you can’t resist, meet your friends at a different location. Some studies have shown that you can lose weight simply by placing those tempting snack items in a difficult-to-reach place, such as the back of the fridge or pantry.

  

Eat more protein at lunch: Here’s a trick that could help you lose weight by eating a bit more. It comes from Nancy Clark, RD, author of Nancy Clark’s Sports Nutrition Guidebook, a best-seller among runners for forty years. Like many nutritionists, Clark believes we often skimp on protein at breakfast and lunch, which leads to greater hunger later in the day.

Instead of buying a half pound (eight ounces) of sliced turkey at the deli counter for your lunchtime sandwich, buy nine ounces, says Clark. At home, divide the nine ounces into three portions of three ounces each. Use all three ounces in your whole-grain sandwich. This lunch will provide substantially more protein than the one ounce of turkey that many put on their sandwiches.

  

Watch those alcoholic drinks: Many of us slip into drinking a little more as we get older, notes Liz Applegate, PhD, a longtime nutrition editor at Runner’s World. Maybe the kids have left the nest and dinnertime is no longer a frantic affair. You can enjoy a cocktail before dinner and some wine with your meal. Alcohol is not a calorie-free treat, however. Quite the opposite: at seven calories per gram, alcohol calories add up quickly. Applegate suggests switching to a glass of sparkling water before dinner. Eliminating one cocktail or glass of wine per evening could subtract thirty-five thousand calories a year. That’s ten pounds right there.