The reason why thin people are relatively more heat-resistant is mainly related to fat content. Fat has the function of heat generation and heat preservation, and the fat content in fat body is high, so it generates more heat and has stronger heat preservation effect, which makes fat people more afraid of heat when facing high temperature environment. In contrast, thin people have less fat, less heat production and easier heat dissipation, so they are relatively more heat-resistant.

In addition, the body surface area of thin people is relatively large, and body heat is more easily dissipated, which is also a reason why thin people are relatively more heat-resistant.

Therefore, thin people are relatively more heat-resistant, because the fat content is less, and it is easier for the body to dissipate heat, rather than less non-fat calories.