Why Body Shape Changes in Middle Age

With age, your hormones shift and your metabolism slows. Here's how to navigate the changes.

Couple of female friends in their forties connecting and staying healthy by practicing yoga by the pool

Medically reviewed in August 2021

Updated on March 11, 2022

If you're journeying through your forties, you may have noticed excess pounds gravitating to your midsection. Why does this happen? In many people it is because of the shifting hormones and slowing metabolism that come with extra birthday candles. They have a way of rewriting the rules of weight loss after the age of 40. Here are some of those changes and how to address them.

Rising blood sugar
At age 30, 10 percent to 20 percent of women are insulin-resistant—which means their bodies ignore signals to absorb blood sugar. By age 60, slightly more than half are insulin-resistant, thanks to drops in estrogen levels. Other hormone shifts, including rising levels of the stress hormone cortisol, send fat to your belly for storage. And, compared to thigh fat, belly fat can be hard on your body. It releases chemicals that interfere even more with insulin. The real kicker is that insulin resistance also seems to interfere with your ability to burn fat, making it even harder to lose the belly.

The fix: Reduce carb intake. It may help to dial back somewhat on bread, white rice, and other carbs. Women who are insulin resistant lose 50 percent more weight when they cut their carbs from 60% of their food intake to 40%—24 pounds in 16 weeks versus 16 pounds—according to a University of Colorado study.

Sleep problems
Tossing and turning all night undermines your body's ability to burn fat and lose weight, even if you're cutting calories to the bone! And poor sleep is a common complaint from early menopause on, often lasting for years and running neck-and-neck with hot flashes. The culprit? Again, hormone swings: dips in estrogen plus jumps in luteinizing hormone (LH).

The fix: Try yoga. A gentle and soothing yoga routine (deep breathing, relaxation poses) boosted sleep quality significantly in a University of Washington study. All it took was a weekly class and 15 minutes of yoga a day to cool off hot flashes and night sweats and relieve stress -- you know, the kind that wakes you at 4 a.m.!

Disappearing muscle
Muscle burns about twice as many calories as fat. Starting in our mid-40s, people lose about 1 percent of muscle mass every year. And that loss accelerates when estrogen dwindles. Because every pound of muscle torches about 7 to 10 calories a day, losing several ounces here and there can gradually lead to a growing waistline.

The fix: Work in some strength training. Challenging your muscles with dumbbells, resistance bands, weight machines, or your own body weight (such as push-ups and chin-ups) helps you build and keep muscle mass while you shift your eating patterns in a healthy direction. Researchers have found that older adults burn up to 12 percent more calories per day -- and that's not counting what you burn working out! -- after 26 weeks of strength training. The Centers for Disease Control and Prevention recommend that everyone do strength training at least twice a week, working all major muscle groups.

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