The choice of food before a nap should avoid foods with high fat, high sugar and high calorie, so as not to cause obesity or affect the quality of sleep. Here are some options that can be used as food before a nap:

1. Fruit: Fruit is rich in vitamins and fiber, which can provide energy and help the body maintain normal metabolic function.

2. Nuts: Nuts are rich in healthy fat and protein, which can increase satiety, promote the body to burn fat and help to lose weight.

3. Pure milk: Milk is rich in protein and calcium, which can provide energy, help to increase muscle mass and promote metabolism.

4. Green vegetables: Green vegetables are rich in fiber and vitamins, which can increase satiety, promote digestion and defecation, and help to lose weight.

5. Yogurt: Yogurt is rich in probiotics and protein, which helps to regulate intestinal flora and promote the absorption and digestion of nutrients.

It should be noted that it is best not to eat too much food before taking a nap, so as not to affect the quality of sleep and gastrointestinal digestion. Moreover, losing weight is not only the adjustment of diet, but also many factors such as more exercise, keeping enough sleep time and positive attitude.