Could lifting dumbbells actually make you smarter? Adam Campbell,

"You don't look like you lift weights."

I've heard this phrase more than once in my life, and it's always delivered by a burly guy in a sleeveless shirt who most certainly does look like he lifts weights. And who's no doubt basing his observation on the standards of a typical musclehead.

That's just it, though: Like most of you, I've never aspired to be a musclehead. Or a powerlifter. Or a strongman competitor. (All of which are fine pursuits, for sure.) So do I look like any of those? Of course not.

But do I look like I lift weights? Absolutely. I'm lean and fit, and my muscles are well-defined, even if they're not busting out of my shirt.

You see, lifting weights isn't just about building 20-inch biceps. In fact, for most women, it's not about that at all, since resistance training may be the single most effective way to lose fat and look great in a swimsuit. What's more, the benefits of lifting extend into nearly every aspect of your health and well-being. So much so that after nearly 12 years of reporting in the field of health and fitness, I've come to one rock-solid conclusion: You'd have to be crazy not to lift weights—even if bigger biceps are the last thing you want. And that's why I wrote The Women's Health Big Book of Exercises.

The truth is, lifting weights gives every woman an edge. Over belly fat. Over stress. Over heart disease, diabetes, and cancer. Lifting even makes you smarter and happier.

Want proof? Here are 20 reasons you shouldn't live another day without lifting.

1. You'll Lose 40 Percent More Fat

This might be the biggest secret in fat loss. While you've no doubt been told that aerobic exercise is the key to losing belly flab, weight training is actually far more valuable. Case in point: Penn State University researchers put overweight people on a reduced-calorie diet, and divided them into three groups—one that didn't exercise, another that performed aerobic exercise 3 days a week, and a third that did both aerobic exercise and weight training 3 days a week.

The results: Each of the groups lost nearly the same amount of weight—about 21 pounds. But the lifters shed about 6 more pounds of fat than did those who didn't pump iron. Why? Because their weight loss was almost pure fat, while the other two groups lost just 15 pounds of lard, along with several pounds of muscle. Do the math and you'll see that weights led to 40 percent greater fat loss.

This isn't a one-time finding. Research on non-lifting dieters shows that, on average, 75 percent of their weight loss is from fat, and 25 percent is muscle. That 25 percent may reduce your scale weight, but it doesn't do a lot for your reflection in the mirror. It also makes you more likely to gain back the flab you lost. However, if you weight train as you diet, you'll protect your hard-earned muscle and burn more fat instead.

Think of it in terms of liposuction: The whole point is to simply remove unattractive flab, right? That's exactly what you should demand from your workout.