For centuries, fasting has been part of human life — from cultural traditions to religious rituals. Today, science is uncovering what our ancestors knew intuitively: periods without food can do more than just slim the waistline. They can help reset metabolism, improve energy, and support longevity.
Dr. Jason Fung, a leading expert in intermittent fasting, has helped bring this ancient practice into the modern conversation. His work is particularly relevant for those in midlife, when metabolism slows, hormones shift, and health risks quietly rise.
Why Fasting Matters More in Midlife
Once we pass 40, many of the old “eat less, move more” rules stop delivering results. Weight gain, especially around the middle, becomes stubborn. Energy dips, brain fog, and sleep changes appear.
Dr. Fung’s research shows that these are often symptoms of insulin resistance — a state where cells become less responsive to insulin, the hormone that regulates blood sugar and fat storage. Fasting helps lower insulin levels, giving the body a chance to burn stored fat and restore metabolic flexibility.
The Science Behind the Benefits
Intermittent fasting in midlife has been linked to:
- Improved insulin sensitivity – helping regulate blood sugar and reduce the risk of type 2 diabetes.
- Fat burning – lowering insulin allows the body to access stored fat for energy.
- Reduced inflammation – fasting can lower markers of chronic inflammation linked to heart disease, arthritis, and cognitive decline.
- Cellular repair – fasting triggers autophagy, a clean-up process where cells remove damaged components.
- Better brain health – fasting may increase brain-derived neurotrophic factor (BDNF), a protein that supports learning, memory, and mood.
Hormonal Nuances in Midlife
For Women (Perimenopause and Menopause)
During perimenopause, oestrogen and progesterone levels fluctuate. These hormones play a role in insulin sensitivity, fat distribution, and appetite regulation. Lower oestrogen levels post-menopause can make insulin resistance more likely, and fat storage more concentrated around the abdomen.
Key considerations:
- Women may respond better to gentler fasting protocols (e.g. 14:10 rather than 16:8) to avoid disrupting cortisol balance.
- Starting slowly — two to three fasting days a week — can help avoid stress on the body.
- Adequate protein is important to preserve muscle mass, which naturally declines after 40.
For Men (Andropause)
Men experience a gradual decline in testosterone from their late 30s onward. Low testosterone is linked to reduced muscle mass, increased fat storage, and lower energy.
Key considerations:
- Fasting can help regulate insulin and lower visceral fat, which may support testosterone balance.
- Combining fasting with resistance training can help offset age-related muscle loss.
- Men may tolerate longer fasts (e.g. 16:8 or occasional 24-hour fasts) more easily than women, but recovery nutrition remains vital.
Popular Fasting Approaches
Dr. Fung’s work highlights that there is no one-size-fits-all. The best fasting method is the one you can sustain.
1. 16:8 Method
Fast for 16 hours, eat within an 8-hour window (e.g. 12 pm–8 pm). Common starting point for most.
2. 14:10 Method
Fast for 14 hours, eat within a 10-hour window — gentler and often preferred by women in perimenopause.
3. 24-Hour Fast (Once or Twice a Week)
From dinner to dinner, or lunch to lunch. Allows deeper insulin reduction but should be approached gradually.
4. 5:2 Approach
Eat normally for five days a week, consume around 500–600 calories on two non-consecutive days.
Making Fasting Work for Midlife
- Start gradually – Shorten your eating window slowly to avoid energy crashes.
- Stay hydrated – Water, black coffee, and herbal tea are fasting-friendly.
- Prioritise nutrient density – Break fasts with whole foods rich in protein, healthy fats, and fibre.
- Listen to your body – Persistent fatigue, dizziness, or irritability are signs to adjust.
- Avoid overeating after fasting – A balanced refeed prevents blood sugar spikes.
Who Should Be Cautious
Fasting isn’t for everyone. Those who are pregnant, breastfeeding, underweight, managing eating disorders, or on certain medications should seek medical advice before starting.
Final Thoughts
For many over 40, fasting offers a way to work with the body’s changing biology rather than against it. Dr. Jason Fung’s message is clear: fasting isn’t about deprivation — it’s about restoring balance.
By tailoring fasting to midlife hormonal realities, both women and men can unlock benefits that go far beyond weight management — from sharper focus to better metabolic health, and possibly a longer healthspan.
Attribution:
This article is inspired by the public teachings and clinical research of Dr. Jason Fung, author of The Obesity Code and co-founder of The Fasting Method. All interpretations are intended for educational purposes and do not imply any direct affiliation or endorsement.
