Intermittent fasting (IF) has become a popular approach for weight management and improving overall health.
With two in three Aussies classified as overweight or obese, it’s no surprise that IF is gaining traction—but do men and women experience the same results?
What is Intermittent Fasting?
Intermittent fasting isn’t about what you eat, but when you eat. It involves cycling between periods of eating and fasting.
One common method is 16:8 fasting, where you fast for 16 hours and eat during an 8-hour window. Another is the 5:2 diet, where you eat normally for five days a week and restrict calories on two non-consecutive days.
Research suggests IF may assist with weight loss, improved blood sugar levels, and better blood pressure control. However, emerging evidence indicates that women may respond differently to fasting than men.
How IF may affect women differently
Dr Stacy Sims, an expert in female physiology and nutrition, argues that intermittent fasting isn’t always beneficial for women. Here’s why:
1. Hormonal Sensitivity
Women’s bodies are more sensitive to calorie restriction due to complex hormonal fluctuations, particularly involving estrogen and progesterone. Sims points out that the female hypothalamus—the brain’s hormone control centre—is highly responsive to energy deficits.Fasting may disrupt hormonal balance more easily in women.
2. Stress Response (Cortisol)
Fasting can trigger a stress response, increasing levels of cortisol—the body’s primary stress hormone. Chronically elevated cortisol can lead to increased fat storage (especially around the abdomen), muscle loss, blood sugar imbalances, and issues with sleep and mood. These effects tend to be more pronounced in women.
3. Metabolic Differences
Some studies suggest that men may experience a short-term metabolic boost during fasting, while women’s metabolisms may slow down in an effort to conserve energy.
Sims advocates for a more personalised, physiology-aware approach to nutrition and training, especially for women.
When to avoid Intermittent Fasting
Intermittent fasting isn’t suitable for everyone. You should avoid IF if you:
- Are pregnant or breastfeeding
- Are underweight or have a history of disordered eating
- Have type 1 diabetes or other medical conditions that affect blood sugar regulation
- Experience fatigue, stress, or disruptions to daily life while fasting
As with any diet or health change, it’s a good idea to consult your GP or a qualified dietitian before starting.
The Bottom Line
While intermittent fasting may offer benefits like weight loss and improved metabolic health, it’s not a one-size-fits-all solution—especially for women.
For more information:
- Dr Stacy Sims – Why Women Shouldn’t Practise Intermittent Fasting
- Cleveland Clinic – Intermittent Fasting for Women
- Dietitians Australia – Intermittent Fasting
- News GP – Intermittent Fasting Study
