It’s unfair, really. Some people can eat whatever they want and never gain an inch — while for the rest of us, yesterday’s Chipotle seems like the reason our pants don’t fit today.
“It’s not solely an aesthetic issue,” Andy Bellatti, MS RD, says of belly fat. “There are actual health risks involved.”
Why do so many of us carry our excesses around our belly?
The answer involves your metabolism, which determines how many calories are too much, your hormones, which steer fat where they feel fit, and your genes. Learning how these factors combine to turn food into belly fat can help you stress less about your weight — and feel more in control whenever you try to lose fat.
Metabolism and Weight Gain: It’s Not What You May Think
Weight gain is the result of a simple issue: You’re eating more calories than your body burns throughout the day. Before we go on, it’s important to know this: the number of calories your body burns per day is only mildly impacted by the amount of exercise you perform.
Most of your calorie burn results from your basal metabolic rate (or BMR). This is the energy it takes for your body to function. The calories you burn are used to power your heart, brain, and every cell of your body all day long.
This, of course, includes burning calories when you sleep. Your caloric burn only drops about 5 percent when you’re sleeping, which gives you an idea of how much energy it takes to run the “machine” that is your body. This accounts for anywhere from 60 to 80 percent of your metabolism.
The amount you move — including exercise, walking around, and even fidgeting — is about 10 to 30 percent of your calorie burn. And, finally, the energy it takes to break down and digest food (known as the thermic effect of food (or TEF) is about 10 percent of your metabolism.
When the amount of calories you eat surpasses the sum of those 3 calorie-burning mechanisms, then your body then has two primary options of what to do with those calories: store them as lean mass like muscle or store it as fat.
Of course, if we could consciously control this process, we’d all shout, “Pick muscle!” But, your body needs a stimulus to send those calories flowing into your guns (or buns, or the hundreds of other muscles in your body). Examples of that stimulus include — you guessed it — exercise.
“If you are pushing yourself with weight-bearing exercise, your muscles will need more calories to grow. And the body knows where to send those calories because the muscle tissue needs repair,” Bellatti says.
”But, if you’re not challenging your muscles, then there’s no cue for the muscles to grow.”
No muscle stimulus? Then your body then chooses option number two: fat storage. Exactly where that fat goes depends in large part on what’s happening with your genes and hormones.
Why Fat Goes to Your Belly
We don’t get to pick where our fat goes. Whether we carry our weight more in our lower body (the “pear shape”) or around our belly (the “apple shape) depends to some extent on our heredity, which is something we can’t influence.
But, the other major determinant of fat storage — our hormones — is something you can influence to a certain degree with your lifestyle choices. Two especially key players in the production of belly fat are insulin and cortisol.
“How we live our lives impacts those hormones, and then those hormones impact our ability to store or release fat,” says Mike Roussell, a nutritionist who holds a Ph.D. from Pennsylvania State University.
“Insulin is basically like a bouncer. It kicks blood sugar out of the blood stream to get it back down to a safe level,” Roussell says. “So when you eat something like carbohydrates or sugar that rises, blood sugar rises, and insulin is going to shovel that sugar out of your bloodstream and it will put it into your fat cells.”
Now, that does not mean that insulin is the cause of fat gain (it’s been researched, and — to this point — that theory has not been supported). After all, insulin also plays a key role in storing calories as muscle.
However, it does mean that if your insulin is consistently elevated, which could be caused by eating sugar all day, every day, then that chronically elevated insulin can become a gateway to fat storage.
The key then isn’t worrying about every food that triggers an insulin response (many do) but making sure that your insulin levels aren’t high at all times.
The other hormone, cortisol, is responsible for your stress response. Its job is to prepare your body for fight or flight by flooding it with enough glucose to power your big muscles.
The problem: Anxiety over work or a lack of sleep can trick your body into thinking it’s in survival mode, triggering a cortisol release. That leads to even bigger problems since cortisol has consistently been linked to belly fat.
Gaining fat can be like compounding interest: you get deeper and deeper into the hole over time, and it becomes harder to get out.
“As you get more fat into your fat cells and they get bigger, it can actually cause an inflammatory response,” Roussell says. “When your fat cell is in that stressed situation and inflamed, it’s not going to want to release the fat.”
How To Limit Fat Gain
Step one in preventing belly fat buildup is to maintain energy balance, where the calories you take in are equal to the calories your body uses during the day. Obviously, this is easier said than done; if it were so simple, then we wouldn’t have more than a third of U.S. residents qualifying as obese. Here are three ways you can get started.
1. Choose Quality Calories
Bellatti says you can make this task a lot less daunting by eating a diet rich in veggies, fruits, whole grains, and lean proteins, which will not only be more fulfilling (thanks to the fiber, protein, and minerals in these foods), but also will be less likely to turn into belly padding when your body processes them.
“Let’s take two people who have a 1,500-calorie-per-day diet,” Bellatti says. “If one of those two has a diet that’s very high in refined grains and added sugar, low in fiber, and doesn’t really include good quality proteins and fats, that’s going to be a diet that’s going to increase blood sugar more. More insulin will be released, and there will be more of a chance of belly fat being stored.”
As an added bonus, you’ll get a lot more bang for your buck when you opt for whole foods over more calorie-dense convenience items. That’s part of the reason why Bellatti insists you shouldn’t buy into those diets where people showed they can lose weight while eating lots of McDonald’s, or even Twinkies.
“Can you lose weight eating 1,500 calories of Haagen Dazs and McDonald’s? Yeah,” Bellatti says.
“But, one, it’s not healthy and, two, it’s not a lot of food. If you’re only eating 1,500 calories of ice cream, volume-wise that’s not a lot of food. You’d be starving.”
2. Control Your Cortisol
Assuming you’re not running from wild animals or doing anything else that would elicit a bona fide stress response, there are a few things you do that ramp up your cortisol: drink caffeine, drink alcohol, freak out about work, and abuse sleep.
Caffeine creates a bit of a conundrum on the weight-loss front. While caffeine has been shown to have a minor calorie-burning effect, repeated doses of caffeine throughout a day have been shown to elevate cortisol levels. The best approach may be to keep your morning joe but pass on the afternoon pick-me-up.
Alcohol can encourage an uptick in cortisol, especially when consumed in a large amount over a short timespan. A glass of wine with dinner is probably okay, but rifling down six beers at happy hour is a bad idea.
Of course, stress itself can elicit the stress response. The good news is that the answer may be right under your nose, in fact, it involves it.
Breathing is one of the easiest and most accessible ways to stop stress and elicit a relaxation response. Taking a few, deep, controlled breaths can turn your “fight or flight” into “rest and digest.”
So the next time you find your mind racing at work and feel the need to hit the panic button, step away from the computer, find a quiet place, and take a seat. Then spend five minutes doing belly breathing.
3. Hit the Sack
Poor or insufficient sleep is another factor that amps up cortisol production, as well as the production of other hormones that can lead to fat storage.
“Lack of sleep totally tips the hormonal balance to fat storage and fat cell inflammation,” Roussell says. “Just a couple of days of poor sleep — four hours or less — changes your hormones such that it makes release of fat from fat cells much more difficult and makes fat storage more likely.”
In fact, one study showed that even a single night of sleep deprivation increased people’s levels of ghrelin (aka the “hunger hormone”) while decreasing leptin (a hormone that makes it easier to say “I’m okay without that donut, thanks”).
So remember, sleep is a lot more than just lying around. It’s an important front in your slim-belly battle. Give it the time (which for most of adults is between seven and nine hours) and attention it deserves.
Adam Bornstein is a New York Times bestselling author and, according to The Huffington Post, “one of the most inspiring sources in all of health and fitness.” An award-winning writer and editor, Bornstein was the Fitness and Nutrition editor for Men’s Health, Editorial Director at LIVESTRONG.com, and a columnist for SHAPE, Men’s Fitness, and Muscle & Fitness. He’s also a nutrition and fitness advisor for LeBron James, Cindy Crawford, Lindsey Vonn, and Arnold Schwarzenegger. His work has been featured in dozens of publications, including The New York Times, Fast Company, ESPN, and GQ, and he’s appeared on Good Morning America, The Today Show, E! News, and The Cheddar.