Alternate Day Fasting Works Equally Well Before and After Menopause: What the Research Shows

Alternate Day Fasting Works Equally Well Before and After Menopause: What the Research Shows

Researchers pooled data from 75 men and women who tried alternate day fasting for 12 weeks. Premenopausal women lost about 5 percent of their body weight. Postmenopausal women and men lost about 6 percent. The study found fasting worked about the same no matter a woman's menopause status.

Medical disclaimer: This article summarises published research for informational purposes only. It is not medical advice and is not a substitute for guidance from a qualified health professional. Always consult your doctor before starting any fasting protocol, especially if you have an existing health condition or take medication.

The Short Version

• What they tested: Whether alternate day fasting — eating very little one day, then eating normally the next — works the same before and after menopause.
• Who did it: S. Lin and colleagues at the University of Illinois at Chicago, published in Nutrition, Metabolism and Cardiovascular Diseases in 2021.
• How many people: 75 adults with obesity, made up of premenopausal women, postmenopausal women, and men. Exact numbers per group are not stated in the abstract.
• How long: 12 weeks.
• What happened: All groups lost weight. Postmenopausal women lost the most, about 6.5 percent, but the difference between groups was not considered meaningful.
• Read the study yourself: Nutrition, Metabolism and Cardiovascular Diseases 2021 →

What They Wanted to Find Out

Many women worry that menopause will make weight loss harder. This study asked a simple question: does alternate day fasting still work once a woman has gone through menopause? Alternate day fasting means eating only about 500 calories one day, then eating normally the next day. The researchers wanted to know if premenopausal women, postmenopausal women, and men all get the same results from this pattern.

This matters because other research has looked at whether time-restricted eating changes women's hormones. Knowing whether fasting still works for weight loss after menopause helps women decide if it is worth trying.

Who Was in the Study

Who they were: All 75 people had obesity. The study combined data from three earlier 12-week alternate day fasting trials. It does not state exact ages or the exact number of women versus men.

What the fasting actually looked like: On "fast days," people ate only about 500 calories. On "feast days," they ate whatever they wanted. They repeated this every other day for 12 weeks.

What Happened

All three groups lost weight, and postmenopausal women lost slightly more than the others.

• Everyone lost weight over time, and this pattern was unlikely to be chance.
• The differences between the three groups were small enough that researchers did not treat them as meaningful.
• Body fat dropped by a similar amount in all three groups.
• Insulin levels and how well the body handles sugar improved similarly across groups.
• Blood pressure dropped about the same amount in all three groups.
• The "bad" cholesterol dropped more in postmenopausal women than in premenopausal women.
• On fast days, everyone ate more than the 500-calorie target — about 400 to 500 extra calories, on average, in every group.

What Did Not Change

• Muscle mass dropped by a similar small amount in every group. Postmenopausal women did not lose more muscle than anyone else.
• Blood sugar levels stayed about the same in all three groups.
• The "good" cholesterol did not change.
• A blood fat called triglycerides did not change either.

What the Researchers Said

The researchers concluded that alternate day fasting's weight loss and health benefits do not depend on being a man or a woman. They also said menopause status did not change how well the fasting worked.

What This Means for You

• If you are going through menopause: this study found no proof that fasting works less well for you than it did before menopause.
• For women specifically: postmenopausal women in this study lost slightly more weight than premenopausal women, and their "bad" cholesterol dropped more too.
• Expect some extra hunger: almost everyone in the study ate more than planned on fasting days. That seems to be normal, not a personal failure.
• Muscle worry? this study found no sign that any group — including postmenopausal women — lost more muscle than the others.
• Want to read more on this topic? see how time-restricted eating affects sex hormones in menopause and whether fasting changes women's hormones generally.
• Curious about the transition years? this related study found fasting works the same before and after the menopause transition.

What This Study Could Not Tell Us

• It combined only 75 people from three smaller trials, split across three groups.
• The exact number of women in each group is not stated in the abstract.
• It ran for only 12 weeks, so it cannot say what happens after a year.
• People reported their own food intake on fasting days, which relies on honesty and memory.
• All participants had obesity, so results may not apply to women at a normal weight.
• The study was partly funded through U.S. National Institutes of Health support, according to the publication record.

The Study Details

Lin, S., Lima Oliveira, M., Gabel, K., Kalam, F., Cienfuegos, S., Ezpeleta, M., et al. (2021). Does the weight loss efficacy (how well it works) of alternate day fasting differ according to sex and menopausal status? Nutrition, Metabolism and Cardiovascular Diseases. PMID: 33358713

Common Questions

Does alternate day fasting work differently for women after menopause?

No. This study found postmenopausal women lost about 6.5 percent of body weight, similar to premenopausal women's 4.6 percent and men's 6.2 percent. The small gap was not treated as a real difference.

Will alternate day fasting make me lose muscle after menopause?

This study found muscle loss was similar across all three groups. Postmenopausal women did not lose more muscle than premenopausal women or men.

How much weight can I expect to lose with alternate day fasting?

In this study, people lost between about 4.6 percent and 6.5 percent of their body weight over 12 weeks. Everyone was eating around 500 calories every other day.

Does menopause change cholesterol improvements from fasting?

Postmenopausal women in this study saw a bigger drop in their "bad" cholesterol than premenopausal women did. Other cholesterol types and blood sugar stayed about the same across all groups.

Do people actually stick to eating only 500 calories on fast days?

Not fully. In this study, people in every group ate about 400 to 500 more calories than the target on fasting days. This happened across all three groups equally.

More Research Like This

• Does time-restricted eating change women's hormones during menopause?
• Fasting works the same before and after the menopause transition
• Does time-restricted eating change women's hormones? No
• Time-restricted eating eased menopause symptoms more than exercise
• Ramadan fasting lowered fat and cholesterol in postmenopausal women
• Fasting plus tai chi improved cholesterol in menopause
• Fasting combined with interval workouts helped women over 50 get fitter

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