Slim people activate there fat stores more rapidly in heavy exercise. Exercising enables them to maintain their body weight more easily.

Obese people mobilise their fat stores in moderate exercise more readily

“Fat burns in the flame of carbohydrate”…to use fat stores efficiently we need to use glucose at the same time. Thin people have lower blood sugars, less liver and muscle glycogen and switch to using their fat stores more readily in heavy exercise.

For an obese person a 2 hour walk will mobilise fat reserves and oxidation more than a 15 minute squash game