Step 1: Know the Basics
Think of your metabolism as an engine. You consume food, and your body breaks most of that fuel down into glucose (that is, sugar). The glucose travels through your blood stream to deliver energy to cells. At the same time, your body produces insulin, a hormone that delivers the glucose and helps ensure blood sugar doesn't get too high. The speed and efficiency at which this all happens is your metabolic rate.
The problem is that as we age our metabolic rate typically slows. Most see a drop of 1 to 2 percent a year, starting in their forties, a decline that drives many of the health woes of middle age. That's because a slower metabolism usually means more stored fat, which can cause an uptick in blood sugar, cholesterol, blood pressure, or inflammation, any of which can encourage even more fat gain. When all these issues occur at once, it's called metabolic syndrome, a condition that half of all Americans over 50 have — not so surprising when you note we also have serious sugar issues. About 14 percent of Americans are diabetic, with another 35 percent on the cusp as prediabetic. As Church says, "It's all interconnected."
Some of the problem can be explained by diet or, most important, carbohydrates, which break down to sugar in the blood. Church says a surprising number of guys he encounters are under the mistaken impression that because they jog or cycle a couple of times a week, they have a blank check to consume sugar-packed snacks and energy bars or a nightly dessert or cocktail (or three). For some, even "healthy carbs," like multigrain bread and whole wheat pasta, can overtax the body's ability to secrete insulin. Over time, flooding the body with sugary foods and drinks can exacerbate insulin resistance — a condition in which cells don't respond to insulin and sugar pools in the blood. This sets you up for diabetes, even if you're not overweight.
The other part of the equation is how you burn the sugar you take in, and here it's not a question of what you shouldn't be doing but what you should. This is where strength training comes in, because muscle is the primary place sugar is burned in the body. "Doing resistance training is like giving yourself a shot of insulin," says Dr. Jamy Ard, a weight management specialist at Wake Forest Baptist Health, in Winston-Salem, North Carolina. "You're getting the glucose from the bloodstream and into the muscles." We used to think that maintaining muscle strength was a quality-of-life issue — you wanted enough brawn to move your furniture or open a stuck mayo jar. Now exercise physiologists and weight-loss doctors regard muscle, and the exercise that pumps it up, as absolutely necessary to keep the metabolic engine running well as we age. "Muscle is the most metabolically influential tissue in your body," Church says. Each pound of it burns an average of seven to 10 calories daily, compared with just two or three calories burned by a pound of fat. For a good idea of how well your metabolism is firing, simply step on a digital scale at the gym and look for the readout of your lean muscle mass. More muscle equals more metabolic horsepower.