Because people in higher financial brackets tend to be more health conscious, in fact they even eat less than poor people. And they work out more.
I observed that a long time ago, when I was growing up my family used to own a catering company, and whenever we had caterings for wealthy people and big companies, they ordered healthier foods, and ate very little, their main concern was not the food but the business talk and the mingling. But sometimes we had caterings for poorer people like government employees, or teachers, or gatherings that companies pay for their employees to attend, and those usually used to go for all the fried food, sugary stuff etc. and they ate like it was no tomorrow.
