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Why it takes longer for women to lose weight after 40 (even Charlize Theron)

If it's getting harder and harder to shed the pounds as you age, you're not alone. Here's how to fight back.
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Charlize Theron in a scene from "Tully." The actress says it took her a year and half to lose the 50 pounds she gained for the role. Kimberly French / Focus Features via AP

The movie “Tully” aims to be an honest depiction of life balancing the demands of a newborn with two other children, in all of its spit-up filled, sleep deprived, utterly exhausted glory. It’s about a mom called Marlo (played by Charlize Theron) who just had her third child and is on the precipice of postpartum depression, until her brother sends a night nanny (Tully) to her rescue.

To play the role, the ever-gorgeous and fit Charlize Theron (who in real life, is a busy mom of two children via adoption) had to gain 50 pounds of excess weight in order to accurately depict what a real postnatal body looks like. Though Theron is no stranger to self-transformation — as her Oscar-winning turn in “Monster” does attest — she says losing the weight she gained for the part took a lot longer at 42 than it did in her 20s.

“It took me a year and a half to lose that weight. It was one of the hardest things that my body went through — and women do this every day,” she told NPR. “When I do it, people are like 'so brave' — and I'm like: No. Women do this all the time and we don't acknowledge it enough.”

Be it baby weight you're still carrying around or those 10 pounds that creep on when your metabolism slows down, losing weight in your 40s and beyond is hard. What’s more, it can be extra maddening when a woman in this age group sets out to do it with a male buddy.

Why does it take longer for women to lose weight, especially after 40?

Sleep deprivation

Whether due to the night-waking of young children or hot flashes from the onset of perimenopause, middle-age is when sleep quality goes downhill for many women. Lack of sleep has long been linked to an increased risk of obesity and diabetes, because it’s harder for the body to regulate glucose leading to something called insulin resistance, which can cause weight gain.

Men are bigger

If you're scratching your head wondering why your husband can lose 25 pounds in two months by making some simple lifestyle changes, here's why. “Women naturally have a higher percentage of body fat and lower muscle mass than men do,” explains Gillian Mueller Goddard, M.D., endocrinologist at Park Avenue Endocrinology & Nutrition PLLC in New York City. “Muscle is more metabolically active than fat is, it utilizes more energy in the form of calories. The average man is also just larger than the average woman, so it takes more calories to maintain a larger body mass. Between these two differences, men can consume more calories to maintain or lose weight than women can.”

We literally have to consume fewer calories to maintain or lose weight.

Slower metabolism

Goddard says estrogen levels begin to decline as a woman begins perimenopause. “As a result, we lose muscle mass, and that loss results in a decrease in metabolism — we literally have to consume fewer calories to maintain or lose weight,” she says. “The loss of estrogen also leads to a propensity to deposit fat in the mid-section, which leads to further metabolic derangement (or an inefficient metabolism). It increases insulin resistance, can lead to pre-diabetes and diabetes, and increases the risk for heart disease.”

Less muscle mass

The loss of muscle mass mentioned above also decreases the number of calories we need to maintain or lose weight, says Goddard. “Additionally, insulin resistance that results from fat deposition in the mid-section can also make losing weight more difficult. Insulin is a hormone. It makes us feel hungry and causes us to store the carbohydrate we eat as fat instead of using it for quick energy,” she explains.

How to Lose Weight After 40

So what can a woman over 40 to do to boost her chances of taking off a few pounds?

1. Move your body

Exercise is key, says Goddard. “Aerobic exercise boosts metabolic rate and weight training increases muscle mass,” she says. Try to incorporate both activities into your weekly workout routine.

2. Cut calories (but not too drastically)

Perri Halperin, MS, RD, dietitian at Mount Sinai Hospital, says losing weight is simply a matter of consuming fewer calories than you expend, but what you eat counts, too. “Be careful of portion sizes, choose lean protein, like chicken and fish, hummus or Greek yogurt, and complex carbohydrates, like whole grains, beans and fresh fruit, use healthy fats in moderation (1 tablespoon of olive oil, ¼ of an avocado) and fill your plate with non-starchy veggies,” she recommends, adding if you reduce your daily caloric intake by 300-500 calories, you could lose a healthy 1-to-2 pounds per week.

Goddard adds: “Many women also benefit from a low carbohydrate diet and avoiding artificial sweeteners, especially in diet soft drinks. This helps keep insulin levels low.”

3. Eat breakfast

Skipping meals messes with your metabolism, sending a signal to your body to cling to stored calories instead of burning them. Swap carb-heavy breakfast options for protein-based foods, like eggs or yogurt, and swap sugary, caloric juices for whole fruit to increase your fiber intake, says Halperin.

If you’re doing all the right things and your weight remains the same, make an appointment with a registered dietitian, who will help you create a customized plan to reach your goals. And if moving more and eating a healthy diet doesn't work, Goddard recommends consulting a physician who specializes in weight loss to treat insulin resistance and pre-diabetes. After all, the battle of the bulge can only get harder to win with age — even for Charlize Theron.

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