How diet affects aging metabolism differently for men and women

By Dr. Liji Thomas, MDReviewed by Lauren HardakerNov 7 2025

Researchers have uncovered striking sex-based differences in how diet influences metabolism with age, revealing that plant proteins and whole grains enhance men’s insulin sensitivity, while moderate wine consumption benefits women.

Study: Sex Differences in Associations Between Diet and Metabolic Health in Older Adults: The Roles of Vegetable Protein and Alcohol Intake. Image credit: simona pilolla/Shutterstock.com

As we age, the body’s metabolism slows, a process that is further exacerbated by a poor diet. Biological sex plays a role in the differential extent of age-associated deterioration in metabolic health. A recent study in Nutrients examined the relationship between diet and various metabolic outcomes in older individuals of both sexes.

How aging alters metabolism

With increasing age, metabolic and functional health decline. This is affected by a complex interplay of genetic, environmental, and lifestyle factors. Dietary patterns, such as the Mediterranean diet, are consistently linked to healthy aging, underscoring the importance of a well-balanced diet.

There is ample evidence that men and women process dietary components differently. Before menopause, women process and clear dietary fats in the liver more efficiently than men of the same age. However, these differences have received little follow-up investigation.

The importance of maintaining healthy blood glucose levels in old age is undisputed. Hyperglycemia and insulin resistance are both related to cardiometabolic disease. As people age, fasting glucose levels tend to rise while glucose tolerance and regulation decline, increasing the risk of type 2 diabetes and cardiovascular disease.

Inflammaging, aging-related chronic inflammation, is a key aspect of aging that contributes to these conditions. It is driven by factors like emerging insulin resistance and high insulin levels, as well as those that cause hyperactivation of insulin-mediated pathways.

High insulin levels in the blood drive accelerated aging. Multiple strategies have been proposed to increase insulin sensitivity and reduce oxidative stress, thereby slowing the aging process. These include caloric restriction, intermittent fasting, and the use of drugs like metformin.

The current study conducted exploratory analyses to investigate the relationship between nutrients and food groups and insulin sensitivity in healthy older adults, stratified by sex.

Assessing metabolic health

The study analyzed data from the Metformin to Augment Strength Training Effective Response in Seniors (MASTERS) study, which comprises healthy older people. The study included 96 participants recruited from university settings, with a median age of 69 years and body mass index (BMI) values ranging from 19 to 34 kg/m².

Most had moderate to high physical activity levels. Participants recorded their food intake over four days using detailed food diaries.

Metabolic health was assessed using measures such as insulin resistance and insulin sensitivity, based on the oral glucose tolerance test (OGTT). These were coupled with body composition measures (dual-energy x-ray absorptiometry and computed tomography).

These were fed into a feasible solutions algorithm (FSA) to find which food groups were most closely linked to insulin sensitivity. Statistical models were adjusted for potential confounders such as BMI and exercise, and corrections for multiple testing were applied.

Key differences between men and women

Men had a higher total energy intake than women, while women consumed more total fiber, driven largely by higher insoluble fiber intake.

When diet was compared with metabolic outcomes, distinct sex-specific patterns emerged. In women, alcohol or xylitol intake was associated with greater insulin sensitivity. In men, by contrast, higher consumption of vegetable protein and whole grains was linked with better insulin sensitivity, suggesting more favorable metabolic health profiles.

In men, several plant-derived nutrients, including inositol, phytic acid, oxalic acid, and vitamin E also correlated positively with insulin sensitivity, whereas a higher intake of refined grains and conjugated linoleic acid (CLA) reduced insulin sensitivity. Despite these associations, overall intake levels of these nutrients were similar between men and women.

Comparable relationships were observed for body fat distribution: greater consumption of plant-based nutrients was associated with a lower android fat percentage (the proportion of abdominal fat in total fat in the android regions).

Insulin resistance in women was associated with a higher BMI, highlighting the role of fat deposition in the development of insulin resistance. Among men, insulin resistance was associated with greater intake of total and trans fats, particularly trans-18:1 fatty acid, demonstrating the metabolic impact of dietary fat quality.

Using linear regression, the model suggested that insulin sensitivity in men was associated with whole grains, nuts, and seeds, whereas in women, it was only associated with alcohol intake. When BMI and exercise were included, model performance improved; however, only higher BMI remained a significant predictor of lower insulin sensitivity.

The inclusion of salty foods reduced the strength of the association between alcohol consumption and insulin sensitivity. After adjustments for multiple comparisons, the associations of alcohol and xylitol with insulin sensitivity in women were no longer statistically significant, indicating that these relationships should be interpreted with caution.

These findings, though preliminary, align with existing evidence supporting the metabolic benefits of plant-based diets, particularly when combined with plant protein. The favorable associations observed with inositol and phytic acid further reinforce the potential value of these plant compounds. Conversely, insulin sensitivity in men showed a negative relationship with the animal-derived fat CLA, likely reflecting a dietary pattern higher in animal fats rather than an isolated effect of this nutrient.

The apparent benefits of xylitol and alcohol in women may instead reflect broader dietary habits, such as a higher intake of dark red and purple fruit rather than other polyphenol-rich foods. Most women in the study consumed wine, which may indicate concurrent consumption of fruit and antioxidant-rich foods rather than a direct effect of alcohol itself.

Why more research is needed

The findings of this study suggest that a plant-rich diet is associated with improved metabolic health in men, leading to increased insulin sensitivity. For women, this was linked to moderate alcohol consumption, although this association did not remain significant after statistical adjustment. Less abdominal fat deposition occurred with increased protein and calcium intake.

These analyses require continuing validation to understand sex-specific differences in the dietary patterns that best support metabolic health with age. The researchers also noted that the findings may not generalize beyond this relatively healthy, primarily Caucasian older population.

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