Research shows men and women respond differently to diet and exercise for body composition changes. A 2026 cross-sectional study of 435 Swiss adults found that physical activity was strongly linked to less belly fat and lower body mass index in men, while diet quality showed stronger associations with body composition in women. Men who ate more fruits and whole grains had significantly less belly fat, while women’s body composition was more influenced by overall diet quality than exercise alone.
A new study of 435 Swiss adults reveals that men and women respond differently to the same foods and exercise. Researchers found that physical activity helps men lose belly fat and build muscle, while diet quality matters more for women’s body composition. Men who eat more fruits and whole grains had less belly fat, while women who ate more meat gained more muscle but also more overall fat. According to Gram Research analysis, these differences suggest that personalized nutrition advice based on sex could be more effective than one-size-fits-all diet recommendations.
Key Statistics
A 2026 cross-sectional study of 435 Swiss adults published in PeerJ found that physical activity was negatively associated with belly fat and body mass index in men, but showed weaker associations in women.
According to research reviewed by Gram, men who consumed more fruits and whole grains showed lower fat mass index compared to men with lower consumption of these foods, while this association was not significant in men for meat consumption.
The 2026 study of 435 adults found that diet quality showed significant associations with body composition measures in women but not in men, suggesting sex-specific responses to nutritional intake.
Research from 435 Swiss participants revealed that meat consumption was positively associated with both skeletal muscle mass index and fat mass index in women, but showed no significant association in men.
The Quick Take
- What they studied: How different foods and exercise affect where men and women store muscle and fat on their bodies
- Who participated: 435 adults from Switzerland ranging in age from 19 to 84 years old, including both men and women from the general population
- Key finding: Men and women respond differently to diet and exercise. Exercise helps men lose belly fat, while what women eat has a bigger impact on their body composition than how much they exercise.
- What it means for you: If you’re trying to improve your body composition, your sex matters for which strategies work best. Men may benefit more from focusing on exercise, while women may see better results by paying attention to diet quality. However, this is one study and more research is needed before changing your personal health routine.
The Research Details
Researchers collected information from 435 adults living in Switzerland and looked at their data from 2021. They asked people about what they ate using a food frequency questionnaire, which is a detailed survey about eating habits. They also measured body composition using bioimpedance analysis, a safe method that sends a small electrical signal through your body to measure how much muscle, fat, and water you have. The researchers then used statistical analysis to find patterns between what people ate, how much they exercised, and where their body stored fat and muscle. They separated the analysis by sex to see if men and women showed different patterns. They also accounted for age, education level, and where people lived, since these factors can affect body composition.
Understanding how men and women respond differently to diet and exercise is important because it could lead to better, more personalized health advice. Most nutrition and fitness recommendations treat everyone the same, but this research suggests that approach might not be optimal. By studying these differences in a real population, researchers can develop recommendations that actually work better for each sex.
This study was published in PeerJ, a peer-reviewed scientific journal, which means other experts reviewed the research before publication. The sample size of 435 people is reasonably large for this type of study. However, because this is a cross-sectional study (a snapshot in time rather than following people over years), it can show associations but not prove that diet or exercise directly causes changes in body composition. All participants were from Switzerland, so results may not apply equally to other populations with different genetics or lifestyles.
What the Results Show
The study found clear sex differences in how body composition responds to diet and exercise. For both men and women, getting older was the strongest factor associated with gaining fat, especially belly fat. Physical activity showed the opposite pattern: people who exercised more had less fat. However, the benefits of exercise were stronger in men. In men, exercise was linked to lower body mass index, lower overall fat, and less belly fat. In women, exercise did not show the same strong connection to these measures. Diet quality showed the opposite sex pattern: it was strongly associated with body composition in women but not in men. In women, eating a higher quality diet was linked to better body composition outcomes. The researchers also found specific food effects that differed by sex. In men, eating more fruits and whole grains was associated with less belly fat. In women, eating more meat was associated with both more muscle and more overall fat. Both men and women who ate more fruits had less belly fat, suggesting this benefit applies to everyone.
The study found that belly fat (visceral fat) responded differently to diet and exercise than overall body fat. Belly fat is particularly important to monitor because it’s linked to health problems like heart disease and diabetes. In men, both exercise and eating fruits and whole grains were associated with less belly fat. In women, eating fruits was associated with less belly fat, but exercise did not show the same strong connection. Skeletal muscle mass, which is the muscle you use for movement, showed interesting patterns. In women, eating more meat was associated with more muscle, but this came with increased overall fat as well. In men, meat consumption did not show a strong association with muscle mass.
This research aligns with earlier studies showing that men and women have different metabolic responses to food and exercise. Previous research has suggested that men and women store fat differently and that hormones play a role in these differences. This study adds to that knowledge by showing these differences in a real-world population and identifying specific foods that matter differently for each sex. The finding that exercise benefits men’s body composition more than women’s is consistent with some previous research, though other studies have found different results, suggesting this area needs more investigation.
This study has several important limitations. First, it only shows associations at one point in time, so it cannot prove that diet or exercise causes changes in body composition. People who exercise more might also eat better or have other healthy habits that affect their results. Second, all participants were from Switzerland, so the findings may not apply to people from other countries with different genetics, diets, or lifestyles. Third, the study relied on people reporting what they ate, which can be inaccurate. Finally, the study did not measure hormones or other biological factors that might explain why men and women respond differently to diet and exercise.
The Bottom Line
Based on this research, men may benefit from prioritizing regular physical activity to improve body composition, while women may see better results by focusing on diet quality. Both men and women should eat plenty of fruits and whole grains, as these were associated with less belly fat in this study. However, these recommendations should be considered preliminary and combined with other health advice from your doctor or registered dietitian. The evidence is moderate strength because this is a single cross-sectional study.
Anyone interested in improving their body composition should pay attention to this research, particularly if you’re frustrated that standard diet and exercise advice doesn’t seem to work for you. Men who want to lose belly fat or improve muscle tone may benefit from emphasizing exercise. Women focused on body composition may want to pay closer attention to diet quality. People from Switzerland may see these results as more directly applicable to their situation. However, people from other countries should be cautious about applying these findings without consulting a healthcare provider.
Changes in body composition typically take weeks to months to become noticeable. If you make changes based on this research, you should expect to see measurable differences in 8 to 12 weeks with consistent effort. However, individual results vary greatly based on genetics, overall lifestyle, sleep, stress, and many other factors.
Frequently Asked Questions
Do men and women need different diets to lose weight and build muscle?
A 2026 study of 435 adults suggests they may benefit from different approaches. Men showed stronger results from exercise for reducing belly fat, while women’s body composition was more influenced by diet quality. However, both sexes benefited from eating fruits and whole grains.
Why does exercise help men lose belly fat more than women?
This study found the pattern but didn’t explain the cause. Researchers suggest evolutionary differences in how men and women store energy, but more research is needed. Hormones, genetics, and metabolism likely play roles in these sex differences.
Should women focus on diet instead of exercise for body composition?
No. This study found diet quality showed stronger associations with women’s body composition, but exercise still matters for overall health. Both diet and exercise are important for everyone, though the emphasis may differ by sex based on this research.
What specific foods should I eat based on this research?
Both men and women benefited from eating more fruits and whole grains, which were associated with less belly fat. In women, meat consumption was linked to increased muscle but also increased fat, so moderation may be wise.
Can I apply these findings if I’m not from Switzerland?
These findings may apply broadly, but with caution. The study only included Swiss adults, so genetics and lifestyle differences in other populations might produce different results. Consult a healthcare provider about applying this research to your situation.
Want to Apply This Research?
- Track your weekly exercise minutes separately from your daily diet quality score. For men, monitor how exercise correlates with changes in waist circumference or belly fat measurements. For women, track diet quality scores alongside body composition changes to identify which specific dietary improvements matter most for your goals.
- Set sex-specific goals: men should aim for 150 minutes of moderate exercise weekly and track belly fat reduction, while women should focus on improving diet quality by increasing whole grains and fruits while tracking overall body composition. Use the app to log specific foods and exercise sessions, then review monthly trends to see which changes correlate with your body composition improvements.
- Measure body composition monthly using the same method (bioimpedance scale, DEXA scan, or tape measurements) rather than relying on weight alone. For men, prioritize tracking waist circumference and exercise consistency. For women, track diet quality scores and overall body composition. Create separate dashboards by sex to compare your progress against the patterns found in this research.
This research shows associations between diet, exercise, and body composition but does not prove cause and effect. Results are from a Swiss population and may not apply equally to other groups. Before making significant changes to your diet or exercise routine, consult with your doctor or a registered dietitian, especially if you have existing health conditions, take medications, or have specific health goals. This article is for educational purposes and should not replace professional medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.