That's Fit

It's one of life's cruel mysteries: Some people are naturally thin, despite never setting foot in the gym, while others count every last calorie and spend a large chunk of their free time sweating away at the gym and still can't seem to drop a dress size. It's called being 'fit but fat' and thankfully, studies show that it's healthier for you than being thin and unhealthy. But while health is so important, it would be nice to be healthy and feel good in a bikini, right?

Trust me, I know what it's like. For years, I was sure the gradual increase on the scale had to be a mistake because I was constantly active. I blamed the tightening of my pants on the dryer, but after a while, there's no denying it. I'm finally seeing the number on the scale go down, but it took fessing up to some hard truths -- namely that what I was doing before just wasn't challenging me any more.

Most of us have a tendency to label all larger people as unhealthily overweight or obese. But some overweight people aren't that way because they sit around eating cheeseburgers on the sofa all day -- believe it or not, some so-called 'fat' people actually exercise regularly. Don't believe me? Check out this woman's account of her journey from fit-but-fat to thin.

So what's the key to breaking out of the fit-but-fat cycle? The key is being honest with yourself and realizing why you ultimately can't lose weight. First, talk to your doctor to rule out any medical issues like Hypothyroidism. Then, take a thorough look at your habits. Yes, you may be eating healthy foods, but you might be eating too much. And although you may be going to the gym five days a week, you might not be working out effectively -- in that case, it's time to see talk to a personal trainer. Or maybe it's all down to the fact that you think working out makes it okay for you polish off a large pizza every day, which doesn't work either.

How did you go from fit-but-fat to thin?

Is thin really in? Not necessarily when it comes to heart health. Recent research suggests that even the significantly overweight can improve their cardiovascular health, without losing a pound. Not only that, but yo-yo dieting -- or repeatedly losing and gaining weight -- can actually harm your heart if you gain back those pounds in dangerous belly fat.

Like our mamas always taught us, it's what happens on the inside that counts. Even if you don't always agree with what you see in the mirror, your HDL , triglycerides, and blood sugar can tell you if you're taking care of your internal health. I don't think that means that if your numbers are good, you get a pass to eat large bowls of ice cream while watching reruns of The Sopranos, like some of us (ahem) would like to do. But what it does mean is that even after getting plenty of activity and eating a healthy diet, you can only dream of the "perfect" body on the outside, you can celebrate the fact that you've got a killer body on the inside, and that's far more important where your health is concerned.

Read more about the healthy, heavy heart at AOL Body.