Best Diets for Women Over 40: What Trials Show

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The best diets for women over 40 are not clearly separated by the trials that compared them head to head. Low-carb, low-fat, Mediterranean, DASH and fasting diets all helped people lose pounds and weight, the gaps were usually small, and the authors of a large JAMA meta-analysis said any diet a person will follow is a reasonable thing to recommend. I am not a doctor, so this guide to healthy eating sticks to what the sources say, who was studied, and where the research skips midlife.

See my guides to nutrition and meal planning for women over 40, foods that boost metabolism and what to eat after menopause. To compare eating approaches against other kinds of programs, start with the best weight loss programs for women over 40.

What is the best diet for women over 40?

There is no proven single best diet. A 2014 JAMA meta-analysis of 48 randomized trials with 7,286 adults found significant loss on any low-carbohydrate or low-fat approach, small differences between named diets, and said this supports recommending any diet plan a person will follow (Johnston et al., 2014). Those trials were not limited to women.

How do the main diets compare in trials?

Eating pattern	Who was studied	Length	What was found
Healthy low-fat vs healthy low-carb (DIETFITS)	609 adults aged 18 to 50, 57 percent women	12 months	5.3 kg vs 6.0 kg lost, no significant difference
Low-fat, Mediterranean, low-carb (DIRECT)	322 adults, average age 52, 86 percent men	2 years	2.9 kg, 4.4 kg and 4.7 kg lost
Low-fat pattern (Women’s Health Initiative)	48,835 postmenopausal women	7.5 years average	1.9 kg below controls at year 1, 0.4 kg at 7.5 years
Named plans including DASH (BMJ meta-analysis)	121 trials, 21,942 adults	6 and 12 months	DASH 3.6 kg at 6 months, smaller by 12 months
Alternate-day fasting vs daily calorie cutting	100 adults, 86 women, average age 44	12 months	6.0 vs 5.3 percent, no significant difference
Time-restricted eating plus calorie cutting vs calorie cutting alone	139 adults with obesity, trial run in China	12 months	8.0 kg vs 6.3 kg, not significant

These are group averages, not personal predictions.

Does a low-carb diet or keto work better for women over 40?

Not significantly, in one large head-to-head trial. In the DIETFITS trial in JAMA, 609 adults aged 18 to 50 (57 percent women, none with diabetes) followed a healthy low-fat or healthy low-carb approach for 12 months. The low-carb group lost 6.0 kg and the low-fat group 5.3 kg, a gap of 0.7 kg that was not statistically significant.

The BMJ analysis saw the same weight loss at 6 months, though a low-carb diet lowered LDL cholesterol less than a low-fat diet (Ge et al., 2020). These trials tested a low-carb diet in general, not strict keto, and not women over 40 specifically.

Is the Mediterranean diet good for women over 40?

It has trial support, though the main weight-loss trial cited here, DIRECT, was 86 percent men. MedlinePlus describes it as mostly plant-based meals with whole grains, fruits, vegetables, nuts, legumes and fish, with olive oil as the main fat (MedlinePlus, reviewed July 24, 2024). In the two-year DIRECT trial in NEJM, 322 moderately obese adults (86 percent men) lost 4.4 kg on a calorie-restricted Mediterranean diet. The BMJ analysis reported that by 12 months the cardiovascular risk factor improvements had essentially disappeared for every intervention except the Mediterranean diet.

One finding concerns older women. In a secondary analysis of 924 adults aged 55 to 75 with metabolic syndrome and overweight or obesity, an energy-reduced Mediterranean pattern with more physical activity lessened lumbar spine bone density loss over 3 years compared with an unrestricted Mediterranean pattern without activity promotion, in women but not men. The authors say longer follow-up is needed. (Vazquez-Lorente et al., 2025).

What about the DASH diet?

DASH was built to lower blood pressure. The National Heart, Lung, and Blood Institute describes vegetables, fruits and whole grains with low-fat dairy, fish, poultry, beans, nuts and vegetable oils, a 2,300 mg daily sodium limit, and says 1,500 mg lowers blood pressure further (NHLBI). The BMJ analysis did link DASH to 3.6 kg more lost than a usual diet at 6 months, with moderate certainty. If you have high blood pressure, ask your clinician whether the DASH diet fits your plan.

Does intermittent fasting work for women over 40?

About as well as cutting calories daily, not better. In a one-year trial, 100 metabolically healthy adults with obesity (86 women, average age 44) lost 6.0 percent of body weight with alternate-day fasting and 5.3 percent with daily cutting, not a significant gap. More people dropped out of the fasting group (38 percent vs 29 percent). One author disclosed a book advance on every-other-day dieting (Trepanowski et al., 2017).

A 12-month NEJM trial of 139 adults with obesity found eating only between 8 a.m. and 4 p.m. on top of a calorie limit gave 8.0 kg lost, against 6.3 kg for the limit alone, also not significant. The trial was run in China and funded by Chinese national research bodies (Liu et al., 2022). Talk to your clinician before trying fasting if you have diabetes, take glucose-lowering medicine, are pregnant or nursing, or have had an eating disorder.

Do low-fat diets work for women after menopause?

Modestly, and without strict dieting. The Women’s Health Initiative randomized 48,835 postmenopausal women to sessions on eating less fat and more vegetables, fruit and grains, with no calorie goals, or to a control group. The intervention group weighed 1.9 kg less after one year and 0.4 kg less after 7.5 years (Howard et al., 2006).

What changes after 40 that matters for what you eat?

Body composition shifts more than the scale. In the NIH-funded SWAN cohort, DXA scans showed fat gain doubled and lean mass began to decline at the start of the menopause transition, continuing until about 2 years after the final period. Total weight did not speed up (Greendale et al., 2019). So the number on the scale may not show what is changing.

Bone health needs shift too. The NIH Office of Dietary Supplements lists 1,000 mg of calcium a day for adults 19 to 50 and 1,200 mg for women 51 to 70, and says research has not clearly shown calcium helps weight loss (NIH ODS, updated September 14, 2023).

How do you choose a diet you can stick with?

In DIRECT, the reported rate of adherence to a study diet was 95.4 percent at 1 year and 84.6 percent at 2 years (Shai et al., 2008). Ask whether you can eat this way at a restaurant, whether the diet fits your budget and health conditions, and whether you would still want to eat it in a year.

NIDDK says safe and successful weight-loss programs typically include an eating plan based on the calories and nutrients your body needs, and that health care professionals often treat overweight and obesity by recommending lifestyle changes (NIDDK, reviewed May 2023). Ask your clinician whether a referral to a registered dietitian makes sense.

Can a meal delivery service help you follow a diet?

None of the trials above tested a delivery brand. My guide to meal delivery for weight loss covers what to check before you buy.

As one example, on the company’s site on October 21, 2026, BistroMD describes itself as a meal delivery service designed by dietitians, with over 150 chef-prepared meals across 7 or more programs. The list includes heart healthy, diabetes friendly, vegan, keto flex, GLP-1 optimized and menopause friendly options. Those are the company’s statements, not trial findings.

Where do weight-loss medicines fit in?

NIDDK says a health care professional may prescribe weight-loss medicine when lifestyle changes are not enough, and that people who take it should try to stick with their healthy eating plan (NIDDK). If you are on a GLP-1 or considering one, my GLP-1 meal plan covers how eating changes with it.

If you decide to ask a clinician about medication, one telehealth route is Shed. On its site on October 21, 2026, Shed says a licensed provider reviews your health form and decides if treatment is appropriate, and that it offers brand-name Zepbound and Wegovy plus compounded semaglutide and tirzepatide. The page also says compounded medications are not FDA-approved. A prescriber decides what is right for you, and results vary.

I am not a medical professional, and this page is not medical advice. Talk to your doctor or a registered dietitian before you change how you eat, especially with diabetes, kidney disease, an eating disorder history, pregnancy, nursing, or a GLP-1 or other prescription medicine.

Frequently Asked Questions

Is it harder to lose weight after 40?

Body composition changes more than total weight. In SWAN, fat gain sped up and lean mass dropped around the menopause transition, but overall weight did not speed up. SWAN did not test any diet, and the trials in the table were not limited to women over 40.

What is the best diet for women over 40 to lose belly fat?

None of the trials above was designed to target belly fat. Their main outcome was total weight.

How many calories should a woman over 40 eat?

It depends on size, activity and goals. The Office on Women’s Health lists eating plans built on 2,200 calories for moderately active women aged 26 to 50 and 1,800 for those 51 and older (page updated October 23, 2025). A clinician or dietitian can set a lower weight loss target.

How fast should I try to lose weight?

The CDC says about 1 to 2 pounds a week makes keeping it off more likely than losing quickly, and warns that unrealistic goals can leave you feeling defeated (CDC).

Can I follow these diets on a GLP-1 medicine?

Ask your prescriber first. NIDDK says people taking weight-loss medicine should try to stick with their healthy eating plan.

Sources

Best Diets for Women Over 40: What the Research Compares