Advertisements may lead you to believe that a certain exercise with a certain product will help you create the ideal physique. But focusing too much on particular muscles can actually hurt you. (Erin Aniker for The Washington Post)

We’re here again: A couple of months from swimsuit season. And you might be looking in the mirror at any number of eyesores — beer belly, thigh rub, bra bulge, love handles, saddlebags — and asking: Can I get rid of that through exercise and diet?

In other words, spot reduction.

“No, it doesn’t work that way,” says Todd Miller, professor of nutrition and exercise sciences at George Washington University. “Fat in your body is like gas in your gas tank. Thinking you can reduce fat from your stomach alone is like saying you want to use gas only from the right side of your gas tank.”

Fat, just like gas in your car, is stored energy. It gets recruited equally from all over your body and sent to the muscles to be burned, Miller says.

But why then do we carry more of it in certain areas?

“Genetics is the most important determinant for where fat is stored,” says Scott Kahan, director of the National Center for Weight and Wellness. “Often we have relatively similar shapes as our parents.” Gender and age are also part of the equation, Kahan says. Men tend to carry more fat in the midsection, and women tend to have more around thighs and hips.

Six-pack: 15 percent body fat

A toned look — let’s say six-pack abs — requires not only low body fat but also a genetic predisposition to have a fairly equal distribution of fat all over the body. (Low body fat means roughly 15 percent for a woman and less than that for a man. In comparison, the American Council on Exercise lists 25 to 31 percent body fat as average for women; for men, 18 to 24 percent is average.)

In other words, Miller says, if you had two men standing side by side, both with 15 percent body fat, but one carries it evenly and the other doesn’t, the former would be more likely to have the six-pack abs.

The best way to achieve 15 percent body fat? “Total body movements, high-intensity drills, adequate rest and a boring diet,” says Gabe Free, a personal trainer in the Washington area. When he was trying to trim fat, that meant a diet consisting of lean proteins and vegetables with a few cheat meals here and there. His breakfast every day was kale and eggs, and his favorite cheat meal was hamburgers. He kept up his usual workout routine, including dead lifts and squats.

“I didn’t lose weight, but I leaned out,” he says. In other words, his body fat percentage — fat-to-muscle ratio — went down.

The reason total body movements (planks, squats, lunges, etc.) are more effective for weight loss and overall fitness than, say, crunches, is that using more large muscle groups requires more energy and builds more muscle, Free says. More muscle means a higher resting metabolic rate.

But that has nothing to do with spot reduction. As Kahan puts it: “You can’t do more squats and expect to lose weight around your thighs.” In other words, the ­proximity of fat to the exercise you’re doing doesn’t matter.

Do 'ab busters' work?

This is why the ever-present ads for various “ab busters” are misleading. The abdominals are a relatively small muscle group and don’t require a lot of energy to be engaged, Free says.

“Ads manipulate you with that image — the lean model,” he says. “But the ab wheel, or whatever it is, didn’t make the model look like that.” More likely, the model looks like that because of age, gender, conditioning, nutrition and genetics (and maybe a little Hollywood magic). “It has nothing to do with the ab wheel,” Free says.

In fact, being overly focused on one muscle group can do more harm than good, Kahan says. It can create muscle imbalances. If the front of the body, including the abs, is too strong and the back is too weak, we get the hunched-over “cave man look.” Aside from being unattractive, that can also cause back pain.

Age is important, too, when it comes to body fat. As we get older, our lean body mass (muscle) tends to decrease, especially in men whose testosterone levels start dropping in their 40s, while fat increases. In aging women, inactivity seems to be more instrumental in fat gain than hormonal changes, Miller says.

Medical procedures

The one thing that truly works for spot reduction, at least from an aesthetic standpoint, is liposuction and other medical procedures that remove fat and fat cells, Kahan says. But he doesn’t advocate liposuction because the procedure doesn’t promote overall health benefits the way that healthy nutrition and exercise does, he says. “For example, it doesn’t lower your blood pressure or your blood sugar.” And if it’s not paired with healthier ­habits, liposuction tends to just shift the fat from one area to another.

Apart from surgery, fat cells never decrease, no matter how many miles you run or how many pounds you bench-press. They are set in childhood and adolescence, and after that they just shrink or balloon depending on your habits.

The takeaway, then, for six-pack purposes and beyond, is that healthy habits are lifelong — and the younger you start, the better.

Boston is a fitness trainer and freelance writer. She can be found at gabriellaboston.com.