What are fasting days and why they matter
There is ongoing discussion about the role of fasting days. Some view them as harmful, others see them as beneficial. Experts from GMTClinic, including endocrinologist Irina Arar, describe fasting days as planned, deliberate calorie restriction or short-term fasting rather than a total refusal to eat. They emphasize that fasting days are a controlled approach, not a blanket diet ban.
In today’s dietary landscape, many people follow a hypercaloric pattern, loading their meals with fats and simple carbohydrates and often overeating. This is what the doctors point to when explaining why fasting days can be relevant. A common misconception is that a fasting day means skipping all food, and some even schedule such days to coincide with holidays. Medical professionals caution that such extreme approaches lack value and can be counterproductive.
Fasting days differ from full fasting, and they are not a magic fix for overeating. They should not replace a consistently balanced and moderate diet on other days. Ekaterina Gureeva from the Atlas clinical network notes that fasting days cannot be used to offset regular overeating on other days.
So what exactly are unloading days about? Irina Arar explains that these days can support pancreatic function and help the body clear toxins, waste from damaged cells, and incompletely digested material. The body then repurposes these components to build new cells, enzymes, and hormones.
Ekaterina Gureeva adds that fasting days are unlikely to produce lasting weight loss or appetite improvements on their own. Often, these days become an attempt to compensate for overeating. She notes that a weekly calorie deficit might not substantially move the scales, especially if activity levels are reduced during fasting days, which can maintain a balance of calories in and out with little to no weight change.
Irina Arar stresses the importance of returning to full, balanced meals after fasting days. Gloomy outcomes are possible if the post-fast period is dominated by high-fat, low-nutrient choices. The aim is to restore nutrition and energy without undoing any potential benefits of the fast.
How to choose an unloading program
There is no shortage of online articles offering tips for organizing fasting days, but medical professionals warn against relying solely on internet advice. Irina Arar emphasizes the need to assess each person’s history and current health before selecting a plan. It is important to identify any gastrointestinal issues, diabetes, anemia, chronic stress, or nutritional deficiencies before starting a fasting regimen.
Equally important is gathering information about physical activity, daily routines, and hormone levels such as insulin and leptin, which influence hunger and fullness. Understanding these details helps to structure fasting days safely and avoid health disruptions.
Where to begin? If a weekend of indulgence is anticipated, Irina Arar recommends reducing calories by half the day before and the day after the event. The goal is a deliberate reduction, not starvation, and the overall balance should be maintained without severe restriction.
A second approach is to schedule fasting days 1 or 2 times per week. The idea is to keep a healthy, balanced diet on non-fasting days and trim daily calories to about 600–800 kcal on fasting days. This method aims to preserve nutrient intake while enabling a restorative effect on the body.
Another common option is the FMD, or Fast Mimicking Diet, developed by researchers at the Institute of Longevity within the University of Southern California’s School of Gerontology. The program initially targeted rejuvenation and also shows potential for weight management by reducing visceral fat. The concept centers on simulating hunger by gradually lowering daily calories to 600–800 kcal over five days, while limiting simple carbohydrates and animal proteins and emphasizing vegetables, legumes, nuts, small amounts of berries, and ample water—at least two liters per day. The FMD can be practiced 2–3 times a year to support health and weight stability, as described by Arar.
Gureeva cautions that fasting days should be limited to once a week to prevent adverse metabolic effects and avoid demotivation or regression. A balanced approach is essential for long-term success.
Which foods suit fasting days
Choosing foods for fasting days should reflect individual tolerances and health goals. Experts generally advise against unbalanced fasting on any single item, suggesting two or three well-chosen options instead of a single heavy food source.
Some people opt for buckwheat, but nutritionist Marina Apletaeva notes that cereals can be high in calories and not ideal for fasting days. Vegetables, especially in soups, along with fermented dairy products or eggs, are safer, wholesome choices. A classic fasting-day menu includes unsalted, oil-free baked potatoes for detoxification, complemented by green cucumbers. Another recommended pairing is kefir with cottage cheese, such as 150 g of cottage cheese for breakfast and a glass of kefir for a second meal, though different combinations can be interchangeable depending on individual preferences.
One nutritionist cautions against vegetable smoothies on fasting days, as they may irritate the stomach. If inflammation is present, weight loss may stall. Certain vegetables like celery, beets, and spinach contain salts that could affect kidney function in some individuals. Protein- and fiber-rich options such as apples, cucumbers, cottage cheese, and kefir are considered effective for fasting days. Carbohydrate intake should be modest, alcohol should be avoided, and it can be helpful to reduce overall portions by about 30–50% while filling extra space with leafy greens. Adequate hydration remains essential on fasting days to support recovery and digestion.