Eating less than the energy required for basal metabolism may affect fat loss. Basal metabolism is the minimum energy requirement for all organs of the body to maintain life. If the daily intake is less than this minimum energy requirement, the body may lose weight in a short period of time, and in the long term, it may also cause fatigue, hypoglycemia, anemia, etc. Fat loss mainly relies on limiting fat intake and reducing excess fat through reasonable exercise. Fat loss mainly relies on limiting fat intake and reducing excess body fat through reasonable exercise. If the daily intake cannot meet the energy requirements of basal metabolism, resulting in fatigue and hypoglycemia, it will affect the fat loss people’s ability to engage in physical exercise, and the fat loss by dietary restriction alone may lead to a rebound in body weight. Therefore, eating less than the energy required for basal metabolism may affect fat loss. People who need to lose fat should adopt a healthy and rational approach to fat loss and seek medical attention if they are unwell.