If you're like many fit women, you've worked your butt off (or some other fill-in-the-blank trouble spots), but your belly fat seems to stick around no matter how well you eat or how hard you sweat. It's incredibly frustrating, so what's the deal? Genetics is a big factor: Studies of twins and families show that the amount of ab fat each person carries is inherited-roughly 30 to 70 percent of the total variation in waist size from person to person is attributable to genetics-and that apple-shaped physiques are more likely to be passed down than other body types.
"You can inherit abdominal-fat-risk gene variations from your mother or your father or from both," says epidemiology professor Lu Qi, M.D., Ph.D., the director of the Tulane University Obesity Research Center. Inheriting these genes from one parent elevates your odds of living with belly bulge, but if you get socked with a lot of genes from both sides, you may be at an even greater risk for belly pudge that won't easily budge. (Did you know you can do an at-home DNA test to find out if you have the gene?)
More than a couple of genes affect abdominal fat. There are 49 to be exact, according to a recent study in the journal Nature. Nineteen of these genes have a stronger effect in women, which suggests that genes may be influenced by hormones, says Kari North, Ph.D., a professor of epidemiology at the University of North Carolina at Chapel Hill's Carolina Center for Genome Studies. One major player in the belly fat game is cortisol, which you most likely know as the hormone triggered by stress.
"Chronic exposure to cortisol can result in a complete shift in body shape, [from hourglass or similar to] around middle and thin arms and legs, even if you're not genetically predisposed to that physique," says Shawn Talbott, Ph.D., the author of The Cortisol Connection. Here's why: When you're under stress your body cranks out cortisol, which springs fat from fat stores and dumps it into the bloodstream to give the liver and other organs energy for the fight-or-flight reaction. Any fat that isn't used for energy gets redeposited in fat stores, primarily in the abdomen.
Whether you have an apple shape because you were born with it or because stress has messed with your waistline, it may trigger unhealthy eating habits that can make it even tougher to shed ab. Researchers at Drexel University found that in women, an increase in the percentage of body fat stored in the abdomen was linked to a 53 percent increase in the likelihood of developing out of control bingeing over a two year period, whereas total body fat was not associated with disordered eating. Researchers think that high percentages of ab fat may interfere with hunger and satiety messages sent to the brain, which can lead to overindulging.
As much as that vicious cycle makes it sound as if get ting rid of ab fat is a lost cause, it's not and there's hope. You just have to be more strategic about how you attack the problem than the woman with the at abs on the treadmill next to you who's probably genetically blessed. Working out will reduce stress (which in turn decreases cortisol) and improve cortisol sensitivity, meaning you secrete less cortisol whenever you are anxious and that your level of the hormone returns to normal more quickly, Talbott says. And a 30-year study on pairs of twins published in the International Journal of Obesity found that physically active subjects (who exercised 30 minutes a day) had a waist circumference that was 3.3 inches smaller than their inactive twins, indicating that exercise can help mitigate genetic influences.
"Those at high genetic risk for abdominal fat can still shed it through exercise; it may just be a more challenging and lengthier process than it is for someone with less genetic risk," says Yann Klimentidis, Ph.D., an assistant professor of epidemiology and biostatistics at the University of Arizona's Mel and Enid Zuckerman College of Public Health, who has conducted research on the subject. Many experts agree, saying that changing your routine and going harder may be the key to finally losing your pooch. Here are two proven approaches to doing just that; work them both into your week to doubleteam ab flab and make a fatbelly breakthrough.
High-intensity interval training
HIIT works to trim you in two ways: It specifically helps to burn off the flab covering your abs, and when it includes the right strength moves, it can simultaneously firm the muscles them selves. The point is to do a lot of reps at a high intensity (at about 80 percent of your maximum effort) and to go heavy on ab-specific exercises.
“Circuits of moves like seated band rows paired with reverse plank holds, plank shoulder taps paired with side plank holds, and burpees paired with high plank holds are effective for losing abdominal fat,” says Cassandra Forsythe, Ph.D., R.D.N., the author of The New Rules of Lifting for Women. Do each pair of moves for 20 seconds total (10 seconds per move), taking a 10-second break between sets, and then repeat the whole circuit eight to 10 times. (Or try our HIIT-filled 30-day bodyweight challenge to get started.) If you’re doing moves with weights, “they should be heavy, but not so heavy that you can’t lift them 12 to 15 times at a pretty fast pace,” Forsythe says.
Cinching core work
To strengthen and cinch in your middle, train your core, not just your abs, every other day. For a quick 360-degree blitz, try doing the Pilates “hundred” combined with the Ab Series of 5 (single-leg stretch, double- leg stretch, single-straight-leg stretch, double-straight-leg stretch, and criss-cross) in quick succession without stop- ping, suggests Pilates instructor Kit Rich, the creator of Fit by Kit with Lucy Activewear. (Try videos for these and other Pilates ab classics.)
"This series works every core muscle, including the deep, notoriously hard-to-reach transverse abdominis," Rich says. Or rather than stick with just Pilates, mix it up with other disciplines. Forsythe suggests four types of core workouts: core endurance, like planks and balance exercises that you hold for 20 to 60 seconds; core strength, including weighted Russian twists and leg raises; core power, such as medicine ball slams
and wall throws; and complete core, including dead lifts and Supermans, which get the small spinal erector muscles in on the action. Incorporate two types of core exercises every time you work out, and make sure to hit all four categories each week. "This ab regimen assures that you work your core from every angle and position," Forsythe says. Bye-bye, Spanx!
