Eating high-calorie food is not the only reason for obesity. When vitamin B 1, vitamin B6, nicotinic acid and other nutrients that can convert adipose tissue into heat are lacking in daily diet, it will also hinder the process of converting adipose tissue into heat, thus causing adipose tissue to accumulate in the body and form obesity. Even if the body is malnourished, some people are not thin, but obese. 2, lack of water in the body will also make adipose tissue unable to fully metabolize, leading to water retention in the body. At this time, the body will absorb water like a sponge, so the body mass (weight) will increase. In addition, simple high-calorie foods, such as oils and nuts, will not have a great impact on body mass (weight) if they are consumed in small quantities. 3. If you eat a lot of sugary food, although the calories it produces are not as high as those of fat, it will be converted into fat and stored in the body because the intake greatly exceeds the calories needed by the body, especially monosaccharides in sugar, such as sucrose, glucose and fructose, which can be directly converted into endogenous triglycerides in the body, leading to hyperlipidemia and obesity.