News | Moderate Calorie Restriction May Slow Ovarian Aging—Monkey Study Offers a New Approach to Extending Fertility
A study led by Professor Francesca E. Duncan’s team at Northwestern University Feinberg School of Medicine found that three years of moderate calorie restriction in female rhesus macaques helped slow ovarian aging and partly preserve follicle types with reproductive potential. The findings were published on May 20, 2025, in Aging-US, Volume 17, Issue 5.
First author Emma S. Gargus and corresponding author Francesca E. Duncan conducted the study in female rhesus macaques, nonhuman primates (NHPs) whose reproductive systems closely resemble those of humans. The study examined whether long-term moderate Caloric Restriction (CR) could slow age-related ovarian degeneration.
Study design: 30% calorie reduction for three years
The team selected female rhesus macaques aged 10–13 years (“younger group”) and 19–26 years (“older group”) and randomly assigned them to a calorie-restriction group, receiving about 30% fewer calories each day, or a control group on a normal diet for three years.
Researchers performed histologic analysis of ovarian tissue from all macaques to assess follicle number and type and changes in tissue structure. Measures included ovarian follicle reserve, ovarian fibrosis, and tissue stiffness.
Although total follicle count still declined with age, calorie restriction significantly increased the number of primordial follicles in older macaques with irregular menstrual cycles. Primordial follicles are a key marker of reproductive potential, and preserving them indicates a stronger ovarian reserve.
How does calorie restriction affect ovarian structure?
Ovarian tissue often develops fibrosis with aging, with increased collagen and reduced hyaluronic acid causing the tissue to stiffen. In calorie-restricted macaques, this process was delayed, suggesting that calorie restriction may improve the ovarian microenvironment and create more favorable conditions for maintaining reproductive health.
Professor Francesca Duncan said that although calorie restriction could not prevent the natural loss of follicles, it did improve follicle quality and the tissue environment, “offering inspiration for future nonpharmacologic interventions.”
Timing of intervention also matters
The study found that timing significantly affected outcomes. Calorie restriction had a clearer effect in older macaques in the transition period before their menstrual cycles had completely stopped, but little effect after menopause. This suggests that if calorie control is used to extend fertility, it may need to begin at an appropriate reproductive stage.
Outlook: dietary intervention may help extend the female reproductive window
Although this study used a primate model and requires confirmation in humans, its results support the possibility that moderate, sustained dietary intervention could help slow ovarian aging and extend the reproductive window.
The study provides new data on the mechanisms of female reproductive aging and lays a foundation for exploring lifestyle-based strategies to preserve fertility.
News | Moderate Calorie Restriction May Slow Ovarian Aging—Monkey Study Offers a New Approach to Extending Fertility
News | Moderate Calorie Restriction May Slow Ovarian Aging—Monkey Study Offers a New Approach to Extending Fertility
A study led by Professor Francesca E. Duncan’s team at Northwestern University Feinberg School of Medicine found that three years of moderate calorie restriction in female rhesus macaques helped slow ovarian aging and partly preserve follicle types with reproductive potential. The findings were published on May 20, 2025, in Aging-US, Volume 17, Issue 5.
First author Emma S. Gargus and corresponding author Francesca E. Duncan conducted the study in female rhesus macaques, nonhuman primates (NHPs) whose reproductive systems closely resemble those of humans. The study examined whether long-term moderate Caloric Restriction (CR) could slow age-related ovarian degeneration.
Study design: 30% calorie reduction for three years
The team selected female rhesus macaques aged 10–13 years (“younger group”) and 19–26 years (“older group”) and randomly assigned them to a calorie-restriction group, receiving about 30% fewer calories each day, or a control group on a normal diet for three years.
Researchers performed histologic analysis of ovarian tissue from all macaques to assess follicle number and type and changes in tissue structure. Measures included ovarian follicle reserve, ovarian fibrosis, and tissue stiffness.
Although total follicle count still declined with age, calorie restriction significantly increased the number of primordial follicles in older macaques with irregular menstrual cycles. Primordial follicles are a key marker of reproductive potential, and preserving them indicates a stronger ovarian reserve.
How does calorie restriction affect ovarian structure?
Ovarian tissue often develops fibrosis with aging, with increased collagen and reduced hyaluronic acid causing the tissue to stiffen. In calorie-restricted macaques, this process was delayed, suggesting that calorie restriction may improve the ovarian microenvironment and create more favorable conditions for maintaining reproductive health.
Professor Francesca Duncan said that although calorie restriction could not prevent the natural loss of follicles, it did improve follicle quality and the tissue environment, “offering inspiration for future nonpharmacologic interventions.”
Timing of intervention also matters
The study found that timing significantly affected outcomes. Calorie restriction had a clearer effect in older macaques in the transition period before their menstrual cycles had completely stopped, but little effect after menopause. This suggests that if calorie control is used to extend fertility, it may need to begin at an appropriate reproductive stage.
Outlook: dietary intervention may help extend the female reproductive window
Although this study used a primate model and requires confirmation in humans, its results support the possibility that moderate, sustained dietary intervention could help slow ovarian aging and extend the reproductive window.
The study provides new data on the mechanisms of female reproductive aging and lays a foundation for exploring lifestyle-based strategies to preserve fertility.
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