You’ve probably heard about spot toning before. Like a unicorn of the fitness world, you suspect it’s more fantasy than fact. Then again, you’ve probably also seen a multitude of commercials and products that promise crazy-impressive results in one specific area with one simple exercise (looking at you, ThighMaster).

And the idea that we could all get legs like Misty Copeland or biceps like Joe Manganiello is pretty tempting. Could a couple hundred lunges or curls be the secret? Bummer alert: It’s not that easy.

Spot Toning Vs. Spot Reduction

First things first: The terms spot toning and spot reduction are often used interchangeably, and both play into the dream of having more muscle definition and less fat in key areas (read: your thighs, arms, or lower abdomen). That said, they don’t actually mean the same thing. With spot toning, the goal is to strengthen and develop a certain muscle or muscle group. Not so much with spot reduction.

“The idea behind spot reduction—and it’s been perpetuated for a long time in the health and fitness space—is that we can target certain areas of the body—’trouble’ spots—and selectively burn off fat,’” says Jessica Matthews, an assistant professor of exercise science at San Diego Miramar College and a yoga instructor. Experts and science have both shown time and again that it’s just not possible. (Sorry, Copeland diehards.)

Take this recent study, for instance. Forty women were divided into two groups: dieters and dieters who also worked their abs. Both groups lost weight, abdominal fat, and lowered their BMI (win-win-WIN!), but they did so at more or less the same rate. This means that the women who added abs work to their repertoire didn’t reap more benefits or end up with slimmer waists than their peers.

More proof comes from tennis players back in the 70s. Researchers discovered that the muscles of a player’s dominant arm (the super-strong and sculpted one used to power most swings) had about the same amount of fat as their non-dominant, less muscular arm. Translation: Area-specific fat loss is a myth.

And just because you’re working a certain muscle doesn’t mean you’re losing the fat that covers that muscle. “Unfortunately, subcutaneous fat loss tends to be more generalized versus just the part that is being trained,” says Lara Carlson, C.S.C.S., president of the New England Chapter of the American College of Sports Medicine.

During sweat sessions, our muscles fuel up with carbs, proteins, and triglycerides (fat)—and these sources can come from anywhere in the body, not just the “problem” area, Carlson says. Bottom line: Ifyou’re hoping for chiseled arms, curls alone won’t get you there.

So… What About Spot Toning?

Now that you know you can’t select where your body loses fat, it’s time for the good news. You can spot tone—if your definition of ‘spot toning’ is strengthening a certain muscle or muscle group, says Chris Freytag, fitness expert and founder of GetHealthyU. People—athletes are perfect examples—do this all the time to improve performance or achieve a certain look (think: bodybuilders with bulging biceps or competitive swimmers who have mega-muscular shoulders).

But spot toning doesn’t come without its drawbacks. While every exercise is beneficial, that doesn’t mean it’s the most effective use of your time. Just put the idea into practice: If you’ve only got 30 minutes to work out, breaking up your workout by body part (chest, then shoulders, then biceps, then triceps, then abs, then—time’s up!) takes a lot longer than hitting your whole body in nearly every exercise.

And there are more benefits to full-body exercises. The more muscles you put to work (and the longer you do so), the more you amp up your calorie burn, Carlson says. So you may be stalling your results by limiting yourself to targeted strength training instead of recruiting as many muscles as possible.

Not only that, but working just one muscle or muscle group makes the body itself more inefficient, Matthews says. It can also cause muscle imbalances, which can mess with your posture and eventually increase your risk for injury (think of how often a professional baseball pitcher hurts his shoulder due to overuse). Your best bet is still to do muscle-specific exercises, but as a part of a larger, total-body routine.

The Takeaway

Since targeted strength training may not be enough to change the way a specific part of the body looks, cranking out a million leg presses won’t necessarily yield crazy-cut legs. “Individuals who want to have certain muscles or muscle groups look more defined can specifically train those areas, but unless they do something to decrease body fat, they may never see those muscles,” Carlson says.

And because frying fat doesn’t happen easily or overnight, it’s safe to say that you can’t just crunch your way to washboard abs. The triple threat that’ll kick it to the curb? Get your heart pumping on the regular (it makes the body use fat for energy), eat well (because you can’t out-exercise a bad diet), and strength train (you’ve got to maintain that muscle mass).

So don’t buy into the marketing ploys. Ultimately, what works is hard work—both at the gym and in the kitchen. Scientists and fitness experts agree that targeted fat reduction is like calorie-free chocolate cake: impossible. And though spot toning is doable, you may see the most gains from a more well-rounded approach. Or as Freytag put it: “If you’re training for life, just work all of your muscles.”