Khaberni - During the early days of fasting, the body primarily relies on the quick sugar stores in the liver and muscles.
However, with the passage of about a week of regular fasting, a significant internal shift begins, where the body changes its main energy source and starts to burn fats more efficiently, and this shift is not sudden, but a smart adaptation to the daily fasting pattern.
Excessive sugars temporarily revert the body's dependence on sugar
Dr. Ahmed Al-Jamal, a consultant gastroenterologist at the Egyptian Ministry of Health, states, "In the first two to three days of fasting, the glycogen reserve, which is the stored form of glucose, is depleted, and after this supply becomes relatively exhausted, the body is forced to search for a sustainable alternative energy source, gradually shifting towards stored fats."
He explains that "By the end of the first week, the body enters a stage known as (metabolic shift), where reliance on sugar decreases and the cells' capability to use fats increases, and the liver begins to produce ketone bodies as an alternative energy source, a process that helps the body maintain its activity despite long hours of fasting."
Dr. Al-Jamal emphasizes the important role of hormones at this stage, as fasting directly affects the energy-regulating hormones.
He says: "After a week, insulin decreases, which allows burning of fats instead of storing them, and glucagon hormone increases, which encourages the breakdown of fats, the hormonal balance related to appetite and metabolism improves, and this hormonal environment is the real key to fat burning."
This effect does not occur in the early days of fasting, as the body naturally prefers easy and quick sources of energy, i.e., sugar, hence, it takes several days to retrain itself to use fats efficiently, and the first week is a period of 'learning', after which metabolic results begin to appear.
Contrary to what some might think, entering the fat-burning stage does not mean weakness or lethargy. On the contrary, many fasters feel more stable energy after the first week, reduced sudden hunger pangs, and improved mental focus as fats provide slower but more stable energy.
Dr. Al-Jamal stresses that the body's success in burning fats also depends on the quality of food. Excessive sugars at iftar can temporarily revert the body's dependence on sugar, whereas protein, healthy fats, and complex carbohydrates help the body continue on the fat burning mode.
