There is no scientific evidence that fasting days help with weight loss. They do not deliver a detox effect either. This view comes from Olga Chukhacheva, an endocrinologist and nutritionist at the Docmed evidence-based medicine clinic network, speaking to socialbites.ca.
Current research indicates that intermittent fasting, including schedules that involve fasting days, does not outperform a well-balanced, hypocaloric diet when it comes to reducing body weight. In other words, when people eat regularly and adequately but consume fewer calories than they burn, they achieve similar weight loss results as those who practice periodic fasting days. Fasting days and fasting itself also do not cause the elimination of toxins, since there is no medical basis for such detox terms. The kidneys, liver, lungs, and intestines perform the body’s natural detoxification processes effectively, without the need for special fasting protocols, according to the doctor.
The doctor emphasized that sharply restricting calorie intake increases the risk of regaining weight after a diet. After a fasting day, many individuals tend to overeat, which can undermine any short-term gains and lead to a cycle of weight rebound.
Additionally, fasting or severe calorie restriction often brings side effects such as fatigue, dizziness, insomnia, nausea, headaches, and constipation. Prolonged dietary energy reduction below 1200 kcal per day can lead to deficiencies in vitamins, macronutrients, and trace elements (for example, iron, folate, B12, calcium) and may contribute to menstrual irregularities in some individuals.
Public health observations indicate that certain groups are at higher risk for metabolic issues, including diabetes. While fasting is not proven to prevent weight gain in these populations, targeted medical guidance can help individuals navigate healthier, sustainable approaches to weight management and metabolic health.