Flat abs aren't just for teenagers, models, or Olympic athletes. Learn how to get a flat stomach with these expert tips.
When You're In Your 20s…
In theory, these should be flat-ab glory years. Though your metabolism starts to drop by 1 to 2 percent when you cross from your teens into your twenties (that means, if you're burning 2,500 calories a day in your teens, you'll burn 25 to 50 fewer calories a day in your twenties, which is why most people gain an average of 1.2 pounds per year at this age), it's still high, says endocrinologist Scott Isaacs, M.D., the author of Hormonal Balance. You're also continuing to churn out large amounts of hormones, like estrogen (this peaks in your late teens or early twenties), which guides your body to store fat in the hips, butt, and breasts instead of the midsection, and growth hormone, which releases fat from its stores in the body so it can be delivered to your muscles for energy, Dr.Isaacs says.
This is particularly true if you consume a lot of carbs. A recent study in the Journal of Nutrition revealed that large amounts of processed carbs (the higher-carb participants in the study were eating 55 percent carbs, 18 percent protein, and 27 percent fat) raise the body's level of insulin, which prevents fat from being unlocked from abdominal fat stores and burned off. Another factor: "Many twentysomethings haven't hit their fitness stride yet; they're doing too much steady-state cardio and not enough strength training and cranking out old-school crunches, a particularly ineffective combination for chipping away at belly fat," says Holly Perkins, a strength-and-conditioning specialist and the author of Lift to Get Lean.Still, even with all this in your favor, four years of keg parties and late-night pizza may have left you with a post grad gut, and those poor eating and drinking habits have a tendency to linger just about as long as your student loan payments. "After graduation, people tend to spend more time sitting at a desk, and this sedentary lifestyle can lead to more weight gain, especially if you're still drinking a lot and not keeping close tabs on your diet," Dr.Isaacs explains.
How to get a flat stomach: Start by shifting your eating habits away from college carbo-loading. (Read up on these healthy beer options if you want to cut down without making your weekend drink-free.) "Help keep insulin at a healthy level by following a moderate-carb diet, in which most of your carbs come from nutritious unprocessed sources like whole grains, beans, fruits, and vegetables," says nutritionist Lisa Young, Ph.D., the author of The Portion Teller. The participants in the Journal of Nutrition study who were given a moderately low-carb diet (43 percent carbs, 18 percent protein, and 39 percent fat) lost 11 percent of their abdominal fat after eight weeks, compared with those on a low-fat, higher-carb diet, who lost only 1 percent ab fat. And because the goal is to burn flab, you need to choose calorie-incinerating workouts.
"It's important to incorporate steady-state cardio, interval training, and strength training," Perkins says. She recommends doing two 35- to 40-minute steady-state cardio sessions a week at a pace that's about a 7 out of 10 on the intensity scale; two 30-minute interval workouts (go for two minutes at moderate intensity followed by two minutes at an almost-all-out pace) to maximize growth-hormone secretion and fat burning; and two days of strength training to build lean muscle mass, which ups your calorie burn. Any type of strength training will be effective, as long as the program gets progressively harder (more weight, more reps) so that you continue to challenge your body. If you're not up for sweating six days a week, you can double up and do the strength training on your cardio or interval days. "Twentysomethings still have metabolism and hormones on their side, so they just need to develop a definitive fitness strategy that includes a balance of cardio and strength training to kick-start their burn and firm," Perkins says. (Want to work out your way to better abs? Try the best ab exercises of all time.)
When You're In Your 30s…
For many women, their thirties are the time to have babies. Pregnancy can cause your rectus abdominis muscles (your front-and-center six-pack muscles) to stretch to the point of separation, a painless condition called diastasis recti, which Brazilian researchers found affected 68 percent of women above the belly button and 32 percent below, when measured at up to eight weeks postpartum. "The muscles usually move back together on their own," says Mary Jane Minkin, M.D., a clinical professor of obstetrics, gynecology, and reproductive sciences at the Yale School of Medicine. "In extreme cases, surgery may be needed to repair the separation." Otherwise, you're probably just dealing with some leftover fat and ab muscles that became stretched out during pregnancy.
That doesn't mean they can't snap right back, but it takes some effort. Luckily, you still have a respectable metabolism in your thirties. (Want to pump it up anyway? Eat these 5 foods to boost metabolism.) While it drops another 1 to 2 percent from the first small dip in your twenties during this decade, that's not really going to catch up to you for another decade or so. Estrogen levels can start to drop for some women in the late thirties as fertility diminishes, but less estrogen isn't an issue until you are well into your forties. And you can still cash in on your growth hormone production for now too.
How to get a flat stomach: Getting your pre-baby belly back requires a two-pronged approach: You need to melt the flab that's covering your abs and strengthen your stretched-out muscles. Trainer Sara Haley, the creator of the Expecting More pre- and postnatal exercise DVD programs, suggests the following time-saving high-intensity routine, which has you moving fast enough to keep your heart rate up to torch calories and incorporates moves designed to tone and tighten your whole core; these exercises are safe for those with diastasis recti, as long as it's not severe.
After warming up, do each of the following moves for one minute: high knees (run in place), plank squats (start in a plank, then jump feet forward and pop up into a squat), knee repeaters (get into a low lunge, clasp hands over your head, and bring your back knee up to your chest while simultaneously bringing your hands down to meet the knee; do one minute per leg), and dead bugs (lie faceup on the floor with your legs raised, knees bent at a 90-degree angle, arms raised toward ceiling, and flex your feet as if you're pushing something away with them while focusing on pulling your belly button into your spine). Rest for one minute, then repeat the circuit two more times; cool down. As much as you may want to throw a crunch into the bunch, don't. "Crunching and twisting movements can make any separation worse because they repeatedly open and close the abdominal muscles," Haley says.
RELATED: 5 Crazy-Effective Crunch Variations
And while juggling work, kids, and a relationship doesn't leave a lot of time for slumber, make sure you get as much shut-eye as you can (shoot for seven to nine hours per night), because sleep deprivation jacks your level of the stress hormone cortisol, which encourages ab-fat storage. If you have kids keeping you up at night, sneak in an afternoon snooze. A Penn State study found that a two-hour afternoon nap can offset the effect that a bad night's sleep can have on cortisol. "Even a short nap—if only for a half hour—may have a small beneficial effect," Dr. Isaacs says.
When You're In Your 40s…
Levels of sex hormones, including estrogen, begin to dip at this age. "Until now, the estrogen receptors' influence on fat deposition in the breasts, hips, and butt have been more powerful than the receptors controlling how much fat is stored inside and outside the abs. As estrogen declines in your forties, the receptors in the abdomen begin to exert more power, so you start to preferentially gain weight there," says Pamela Peeke, M.D., the author of Fight Fat After Forty. Not only does metabolism drop by another 1 to 2 percent from when you were in your thirties—one study found that people can lose as much as 8 percent of their calorie-burning muscle mass from age 40 to 50 if they haven't been taking preventive steps—but growth hormone is also dwindling (one University of Virginia study found that there's about half as much at 45 as there is at 25).
How to get a flat stomach: There's not much you can do on your own about the loss of estrogen, but a surefire way to boost growth hormone is to go hard at the gym. "Moderate- to high-intensity programs with multiple sets, high reps, short rest intervals, and exercises that target multiple large muscle groups at one time produce substantial acute growth hormone responses," says Nicholas Ratamess, Ph.D., a professor of health and exercise science at the College of New Jersey, who suggests working out intensely at least three times a week for 30 minutes. A review of research in the Journal of Applied Physiology found that in 25- to 43-year-old women, regular high-intensity aerobic exercise resulted in a twofold increase of growth hormone release over 24 hours.
As for muscle loss, it's somewhat preventable. "If you're staying physically active and lifting weights, you should be holding on to about the same muscle mass you had in your thirties," Dr. Peeke says. Research in the journal Physician and Sportsmedicine suggests that cardio can also be effective at helping you pack on muscle or maintain it. The study found that intense aerobic exercise (running, biking, or swimming four to five times a week) reduced muscle loss in athletes ages 40 and up, because regular exercise stimulates protein synthesis (repair and maintenance of muscle) and boosts muscle mass and strength. You can also help build and maintain muscle mass by eating 50 to 60 grams of high-quality protein a day; a nice mix of sources could include a cup of cottage cheese, Greek yogurt, legumes, and a piece of fish or chicken. Finally, no need to get discouraged: Keep in mind that you can start reversing age-related ab issues at any time in life. "If you exercised in your twenties and thirties, your forties will be a breeze," Dr.Peeke says. "The great news is that you can start in your forties and start seeing long-lasting results—it's never too late."
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This article originally appeared on Shape.com.