Belly fat is bad news, and not just because you'd like to show off flatter abs at the beach. More and more research is suggesting that waist size is a bigger risk factor for serious diseases than your overall body fat percentage. The main culprit: Visceral fat, the kind that's found deep within your abdomen (as opposed to subcutaneous fat, which sits right under the skin).
Visceral fat, which surrounds your internal organs, is metabolically active, meaning it releases chemicals into your body that can cause oxidative damage, says cardiologist Holly S. Andersen. Translation: Excess belly fat damages organs and blood vessels so that it ups your risk of high blood pressure, high cholesterol, stroke, heart disease, diabetes, some cancers, and even dementia.
Okay, so you accept that a round middle is dangerous, but what can you do about it? Avoiding added sugars and processed carbs can go a long way, says Andersen. And everyone can benefit from eating a more Mediterranean-style diet, with its emphasis on fresh produce, whole grains, limited red meat, and healthy fats. Getting off the couch a little more regularly can't hurt, either. "Anything you can do to reduce your waistline, even if it's a quarter of an inch, can make you healthier," notes Andersen.
That said, some people seem to have a much harder time than others when it comes to whittling their middle—and it's not due to random bad luck. Here are a few scientific reasons why any weight you gain seems to go straight to your tummy—and stay there...
Your Mum Was Apple Shaped
A lot of what determines where you store fat comes down to genetics. A quick look at your family tree should reveal if your clan tends to be apple-shaped or pear-shaped. Those whose genes push them into the apple category may have to be extra diligent about getting lots of physical activity and limiting their calorie intake if they want to stop their bellies from protruding.
Your Hormones Are Shifting
Around menopause, even formerly pear-shaped women—who carry most of their weight on their hips and thighs—often notice that their bellies start to grow. A drop in estrogen, coupled with your metabolism naturally slowing a bit as you age, is likely to blame. Building more muscle through strength training (and concentrating on your core) should make a difference.
You Have PCOS
Polycystic ovary syndrome affects around 10 to 20% of women during their reproductive years. These women have higher than usual testosterone levels and also often find themselves gaining weight, especially around the middle. Since men are more likely to be apples than pears, it's thought that those high testosterone levels might cause this typically "male" pattern of weight gain. Other PCOS symptoms include irregular periods, excess body hair, and acne. If you suspect you might have this condition, talk to your doctor; you may need medication.
You're Not Getting Enough Sleep – Or You're Sleeping Too Much
You just can't win! Regularly getting 5 hours of sleep a night or less has been linked to an increase in belly fat, but so has getting 8 hours or more. "We still have a caveman's physiology," Andersen says. "If we're sleep deprived, our metabolism will decrease to preserve energy, and we'll eat things we know we shouldn't." The search for easy energy in the form of fries or a doughnut is a relic of primitive days, when our early ancestors literally didn't know when they'd be able to eat next. That's why their bodies stored those quick calories as fat, particularly around the middle, she explains.
Researchers aren't exactly sure why those who slept a lot also put on extra belly fat, but it's possible that more time in bed equals less time being active. Everyone's sleep needs are different, but your sleep sweet spot is probably between 7 to 9 hours a night.
You're Seriously Stressed
Experts have long known that frazzled folks are more likely to accumulate belly fat; now they're learning more about why. When you're under pressure, your body pumps out cortisol, a hormone that wreaks havoc in at least two ways. For starters, it makes you more likely to seek out fatty, sugary foods that provide quick comfort. Cortisol also alters your body chemistry so you burn off fewer of those calories (and store more as fat), says Andersen.
Although an annoying e-mail from your boss might have sent you into a tailspin, the resulting cortisol spike is another vestige of earlier times when a sense of panic signaled an actual life-or-death situation. Everyone gets stressed on occasion, but if feel like you're chronically in fight-or-flight mode it might be time to get help —or at least a good yoga class.