Intermittent Fasting
In brief
Section titled “In brief”- Intermittent fasting alternates fasting periods with eating windows
- During fasting, the body switches to recovery and fat burning
- 16:8 is the most commonly used form (16 hours fasting, 8 hours eating)
- Improves insulin sensitivity, lowers liver fat and inflammation
- The quality of the first meal is crucial
What is intermittent fasting?
Section titled “What is intermittent fasting?”Intermittent fasting (IF) is an eating pattern where phases without calorie intake alternate with eating windows.
During fasting, the body switches to:
- Recovery of cells and tissues
- Fat burning as energy source
- Normalization of hormonal signals
Nutrient sensing systems
Section titled “Nutrient sensing systems”Fasting influences three important signaling pathways that determine energy status and control cell growth, recovery, and energy distribution:
| System | Effect during fasting |
|---|---|
| Insulin | Drops during fasting and promotes fat burning |
| mTOR | Inhibits growth and activates recovery with low amino acid levels |
| AMPK | Rises with energy deficit and stimulates mitochondrial biogenesis |
Cell-biological effects
Section titled “Cell-biological effects”Fasting activates important repair processes at the cell level:
| Effect | Meaning |
|---|---|
| Autophagy | Breakdown of damaged proteins and cell parts |
| Mitophagy | Cleaning and renewing mitochondria |
| DNA repair | Activation of stress-response pathways |
| Lower inflammation | Reduced oxidative stress |
Metabolic effects
Section titled “Metabolic effects”The metabolic benefits of intermittent fasting:
- Improved insulin sensitivity
- Increased fat burning and decreased liver fat
- Decreased fasting glucose and triglycerides
- Increased metabolic flexibility
Forms of intermittent fasting
Section titled “Forms of intermittent fasting”| Form | Explanation | Suitable for |
|---|---|---|
| 14:10 | 14 hours fasting, 10 hours eating | Easy entry, beginners |
| 16:8 | 16 hours fasting, 8 hours eating | Most commonly used, good metabolic impact |
| 18:6 | 18 hours fasting, 6 hours eating | More intensive recovery |
| 24-hour | Eating once per day | Stronger mTOR inhibition |
| ADF | Alternate Day Fasting | Powerful, alternating fasting structure |
| 36 hours | Skip a day | Only under supervision |
What is allowed during fasting?
Section titled “What is allowed during fasting?”During the fasting period, the following are allowed:
| Allowed | Not allowed |
|---|---|
| Water | Calories |
| Tea (without sugar/milk) | BCAAs |
| Black coffee | Sweeteners |
| Electrolytes (without sweeteners) | Milk or cream |
Indications
Section titled “Indications”Intermittent fasting can be used for:
- Insulin resistance
- Metabolic syndrome
- Fatty liver (NAFLD/MASLD)
- Hypertension
- Type 2 diabetes (guidance required)
- Overweight
- Chronic inflammation
Contraindications
Section titled “Contraindications”Intermittent fasting is not suitable for:
- Pregnancy or breastfeeding
- Eating disorders (current or in history)
- Underweight or frailty
- Use of insulin or sulfonylurea without guidance
- Severe liver or kidney function disorders
Quality of the first meal
Section titled “Quality of the first meal”The first meal after fasting largely determines the metabolic response for the rest of the day.
Guidelines:
- Choose a protein-rich, unprocessed, and low-carbohydrate meal
- Avoid fast carbohydrates that immediately cause a high insulin spike
- A high-quality first meal promotes satiety, fat burning, and metabolic flexibility
| Good choice | Avoid |
|---|---|
| Eggs with vegetables | Bread, crackers |
| Fish or meat with salad | Muesli, granola |
| Avocado, nuts | Fruit juice, fruit |
| Full-fat yogurt (unsweetened) | Sweetened yogurt |
Maximum two eating moments
Section titled “Maximum two eating moments”To fully benefit from intermittent fasting, a clearly defined eating window works best.
Two complete meals per day provide sufficient energy and protein intake without metabolic interruptions:
- No snacks between meals
- Two nutritious meals support longer mTOR rest
- Improved insulin sensitivity through fewer eating moments
Summary
Section titled “Summary”| Aspect | Recommendation |
|---|---|
| Beginners | Start with 14:10 or 16:8 |
| During fasting | Water, tea, black coffee |
| First meal | Protein-rich, low-carb |
| Eating moments | Maximum 2 per day |
| Guidance | With diabetes or medication |
Veelgestelde vragen
What is intermittent fasting?
Intermittent fasting (IF) is an eating pattern where phases without calorie intake alternate with eating windows. During fasting, the body switches to recovery, fat burning, and normalization of hormonal signals.
What can I drink during fasting?
During fasting you may have water, tea, black coffee, and electrolytes without sweeteners. No calories or BCAAs, as these interrupt the fasting process.
Which form of intermittent fasting is best?
16:8 is the most commonly used form with good metabolic impact: 16 hours fasting, 8-hour eating window. For beginners, 14:10 is an easy entry. More intensive forms like 18:6 or 24-hour fasting provide stronger recovery but are harder to maintain.
For whom is intermittent fasting not suitable?
Intermittent fasting is not suitable during pregnancy or breastfeeding, with eating disorders, underweight or frailty, use of insulin or sulfonylurea without guidance, and severe liver or kidney function disorders.
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