From the Guidelines
Intermittent fasting can be an effective approach for weight management and potential health benefits, and it is recommended as a dietary intervention for those who are suitable, as shown in a recent study published in 2023 1.
Key Points to Consider
- Intermittent fasting involves regular periods of no or very restricted intake, typically less than 25% of caloric need, and can be as efficacious as conventional low-calorie diets 1.
- The most common methods of intermittent fasting include the 16/8 method, the 5:2 diet, and alternate-day fasting.
- To implement intermittent fasting, start gradually by extending your overnight fast to 12 hours, then slowly increase to your desired fasting window.
- During fasting periods, consume only water, black coffee, or unsweetened tea, and when eating, focus on nutritious whole foods rather than processed items.
- Intermittent fasting works by triggering metabolic switching, where your body depletes glucose stores and begins burning fat for energy, potentially improving insulin sensitivity and cellular repair processes.
Important Considerations
- While generally safe for healthy adults, those with medical conditions (especially diabetes), pregnant or breastfeeding women, and people with a history of eating disorders should consult healthcare providers before starting 1.
- Expect initial hunger, irritability, and fatigue as your body adjusts, but these symptoms typically improve within 1-2 weeks.
- A study published in 2022 found that time-restricted eating, a form of intermittent fasting, can enhance fat loss, reduce oxidative stress, improve cardiovascular endpoints, and decrease glucose and insulin levels 1.
Recommendations
- Intermittent fasting can be recommended as a dietary intervention for weight management and potential health benefits, but it is essential to consult with a healthcare provider before starting, especially for individuals with medical conditions or special needs 1.
- It is crucial to focus on nutritious whole foods and a balanced diet during eating periods to ensure adequate nutrition and minimize potential side effects.
- Gradually increasing the fasting window and listening to your body's needs can help minimize initial side effects and improve overall adherence to the intermittent fasting regimen.
From the Research
Benefits of Intermittent Fasting
- Intermittent fasting has been linked to improvements in dyslipidemia and blood pressure, and can lead to a decrease in weight 2
- It may present independent health benefits, such as improvements in insulin sensitivity and fat mass, particularly when fasting duration is extended beyond sixteen consecutive hours 3
- Intermittent fasting can counteract disease processes and improve functional outcome in experimental models of age-related disorders, including diabetes, cardiovascular disease, and neurological disorders 4
- It can also increase life and health span, enhance intrinsic defences against oxidative and metabolic stresses, and improve cognition 5
Types of Intermittent Fasting
- Alternate-day fasting, where individuals alternate between days of normal eating and days of fasting or restricted calorie intake 2
- Time-restricted feeding, where the day's food is consumed over a restricted period, such as 6-8 hours, allowing for 16-18 hours of fasting 2, 4
- 5:2 fasting, where individuals eat normally for 5 days and restrict calorie intake to 500-600 calories on the other 2 days of the week 3
- Periodic fasting, where individuals fast or restrict calorie intake for extended periods, such as 2-21 days 4
Safety and Efficacy of Intermittent Fasting
- Intermittent fasting appears to be an equivalent approach to daily calorie restriction for inducing weight loss, although long-term evidence is limited 6
- There is still some concern around the safety and feasibility of intermittent fasting compared to daily calorie restriction, which has not been well-studied to date 6
- The underlying cellular pathways that are differentially activated in intermittent fasting compared to daily calorie restriction require further investigation in humans 6