How the Female Body Changes in Your Forties

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On July 18, 2025

Physical Changes

Body changes in women at 40 typically arise from declining levels of estrogen. The most common and noticeable physical changes for women over 40 are weight gain, skin changes, and fatigue, says Deepa Iyengar, MD, a family medicine doctor and a professor at McGovern Medical School at UTHealth Houston. But fading estrogen can lead to other symptoms, too.

Weight Gain

As hormones fluctuate in your forties, your metabolism changes, often causing weight gain.

This can happen even if you follow the same diet and exercise habits you did before 40, says Dr. Iyengar.

Fat deposits not only grow but can also shift location to the waist. “It’s not just the numbers on the scale — we notice we’re getting a little thicker around the middle,” says Dr. Lansen, who says this also increases risk of cardiovascular disease.

Muscle Loss

Starting at 40, muscle mass and overall strength declines by 8 to 15 percent per decade. As with metabolic changes, estrogen shares responsibility for muscle loss after 40.

But muscle loss in women may also come from falling testosterone levels, says Lansen.

Skin Changes

Skin changes in your forties often start with wrinkles and fine lines from the loss of collagen and skin elasticity, says Iyengar. You may also notice sudden flushing, which happens in about 75 percent of women going through perimenopause.

Your skin may feel a little saggier and drier, which comes with falling estrogen levels, says Lansen. Many women in this age group also report new skin diagnoses like eczema and allergic dermatitis.

Some women in their forties notice age spots, but these happen more often after 50. If you notice a new skin discoloration, let your provider know.

Thinning Hair

Hormonal changes can affect your hair follicles — structures in your skin that grow hair. This can cause your hair to get thinner, lose volume, or change texture, but not all women experience this.

“It’s not the same as male pattern baldness, but we do notice some hair loss, particularly at the crown of the head,” says Lansen, who adds that thinning hair can be genetic, from aging, or from hormone changes.

Joint Pain

Estrogen helps the fluid and cartilage at your joints cushion your bones, so when this hormone dips in your forties, joint cushion can lessen, causing pain.

Studies show back pain, joint stiffness, and bone pain happen most often in women with a higher BMI.

Vision Changes

As hormones fluctuate throughout adult life, women often experience vision changes like dry eyes and blurry vision. After 40, estrogen and progesterone levels change, causing these symptoms more often.

Changes in Bladder Control

Declining estrogen doesn’t just weaken skeletal muscles — it can do the same to the muscles of your pelvic floor. This lower muscle tone can make it harder to hold in urine, especially when you cough or sneeze.

“[Urinary incontinence] doesn’t necessarily happen to everybody, but it does happen to a number of people,” says Lansen. Women who have experienced pregnancy are more likely to have these leaks as they age.

Fatigue and Sleep Challenges

Women going through perimenopause often experience new sleep disturbances, like insomnia, sleep-related breathing disorders like sleep apnea, and movement disorders like restless legs. The culprits in these sleep challenges are — once again — estrogen and progesterone, which also affect sleep quality.

Hot flashes and night sweats can steal your sleep, too, and missing sleep can lead to daytime fatigue.

“For people who have been great sleepers their whole lives, suddenly they might notice that insomnia is setting in, leaving them feeling lethargic, dragging their feet, and feeling low motivation,” says Lansen.

Brain Fog

Studies continue to uncover more evidence that declining estrogen can affect how well your brain works, and many women experience brain fog, affecting learning and memory. Issues with brain function can also happen alongside other symptoms of midlife, like depression and sleep problems.

Brain fog can feel scary, says Lansen. “But it tends to recover after menopause.”