Intermittent fasting (IF) encompasses several approaches, such as the 5:2 diet, alternate-day fasting and time-restricted eating (TRE). These methods alternate periods of fasting with free meals, offering flexibility that can be easier to follow than traditional diets.
- 5:2 diet: Reduces calories for two non-consecutive days a week. It's simple and requires no calorie counting, making it accessible and sustainable.
- Time-restricted diet (TRE): restricts meals to a time window, often 8 hours (16:8), which aligns with biological rhythms and promotes better regulation of blood sugar, digestion and weight. While these approaches promote fat loss, they can also lead to a reduction in muscle mass. Physical exercise, particularly walking, jogging and swimming, is therefore recommended to preserve muscle mass and improve cardiovascular and mental health
The studies
A review of 23 studies analyzed the combined effects of intermittent fasting and exercise over at least 4 weeks. The results show that this combination reduces body fat, irrespective of initial weight.
However, the impact on muscle mass and metabolic health varies according to the type and intensity of exercise.
IF does not interfere with the benefits of exercise and may even improve certain physical capacities, such as endurance and explosive strength.
Impact of Intermittent Fasting on Health
Intermittent fasting could improve health by reducing visceral fat, decreasing waist circumference and improving certain metabolic markers such as blood glucose, triglycerides and diastolic blood pressure. Compared with continuous calorie restriction, IF appears to be slightly more effective in reducing body fat and increasing HDL (“good”) cholesterol. However, both methods are effective for weight loss and metabolic health.
The effects of IF vary according to method and duration, which underlines the importance of tailoring the approach to each individual.
The role of exercise and the environment
In addition to promoting weight loss, exercise improves liver function and cardiovascular health. It is recommended to limit sedentary lifestyles, sleep well, stop smoking and maintain a healthy lifestyle to prevent diseases such as non-alcoholic fatty liver disease (NAFLD).
Neurodegeneration and Intermittent Fasting
IF may also offer a promising solution for neurodegenerative diseases, by reducing inflammation, improving mitochondrial function and promoting neuronal regeneration. Research suggests that it improves the blood-brain barrier and reduces the accumulation of toxic proteins, which could prevent or slow the progression of diseases such as Alzheimer's and Parkinson's.
Limits and outlook
Current research has several limitations:
- Small sample size and short study duration (less than 12 weeks).
- Lack of diversity in participants, often excluding women, the elderly and at-risk populations.
- Adherence to fasting and exercise is often poorly measured.
Longer, more diversified and better-controlled studies are needed to better understand the impact of intermittent fasting and exercise, particularly for chronic diseases.
Conclusion
Intermittent fasting, in combination with exercise, shows promising results for weight management and overall health. However, better-quality research is needed to confirm its effects on chronic diseases and better target the populations that benefit most
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