Intermittent Fasting: What It Is and How It Works
Learn about intermittent fasting, how it affects metabolism, and which mistakes to avoid.
Contents:
How does it work in your body?
What is Intermittent Fasting?
Intermittent Fasting (IF) is an eating pattern that alternates periods of normal food intake with periods of strict or complete fasting. It doesn’t dictate what you eat, but when you eat, and can involve fasting periods lasting hours or even full days.
How does it work in your body?
During fasting, the body depletes its glycogen stores and shifts to lipolysis, producing ketones—the so-called “metabolic switch.” This supports metabolic flexibility, increased insulin sensitivity, and the activation of processes such as autophagy.
Main IF protocols
Time-Restricted Eating (TRE): e.g. 16 hours fasting and 8 hours eating (16:8).
5:2 Diet: two days per week with ~25 % of normal calories or complete fasting.
Alternate-Day Fasting (ADF): complete or partial fasting every other day.
Evidence-based benefits
Weight & fat loss: reductions of 3 %–8 % within 2–26 weeks.
Improved cardiometabolic health: lower blood pressure, LDL, and triglycerides.
Recovery & longevity: autophagy, antioxidant effects, and neuroprotection.
Common mistakes & pitfalls
Overeating within the eating window: cancels out the calorie deficit.
Inadequate protein intake & exercise: may cause muscle loss.
Unsuitable for certain populations: type 1 diabetes, pregnancy, eating disorders.
Energy & social costs: headaches, fatigue, and social limitations.
Who might it not suit?
Individuals with a history of eating disorders, type 1 diabetes, pregnancy/breastfeeding, or serious illnesses should first consult a doctor and a qualified dietitian. Not recommended for older adults without medical supervision.
Conclusions & Useful Tips
Intermittent fasting is a powerful tool for wellness and weight loss when applied correctly:
Shorten the eating window (e.g. 16:8).
Combine with exercise and sufficient protein intake.
Avoid overeating after fasting.
Monitor your body’s signals.
Begin with medical and nutritional guidance—whether you belong to a vulnerable group or not.