First, the elite have a high degree of pursuit of health, so they usually spend time exercising, so when they are healthy, their bodies become light, not greasy or obese. And many thin poor people are caused by malnutrition.
Second, the elite can generally bear high fitness costs; The poor may not have enough to eat, or be weak and need a good rest and conditioning, but they become thinner because they can't afford this conditioning or even have no time to exercise.
Third, with different ideas, elites will consciously improve themselves at all levels, such as good health and controlling body fat rate, but the poor think that spending that money is better than letting me go somewhere to play or staying at home rather than spending money to "suffer"