During weight loss, it is reasonable to donate blood normally. However, during weight loss, the diet is strictly controlled and the body is in a more depleted state, so if you donate blood during this period, it will have a little effect on the patient’s body. The main manifestation is that the patient may experience dizziness, weakness, panic, sweating, or even an uncomfortable feeling similar to hypoglycemia. It is recommended not to donate blood during the weight loss period without special circumstances. If you do need to donate blood, about 200ml is enough and try not to donate too much. After donating blood, patients should take proper rest and take food with high sugar content or nutrients to help the body recover.