Let's be generous and say that a person's body runs on 1600kcal/day, which is pretty low and the other 1800kcal/day which is kinda average. The difference in weight loss between these two over six months eating and exercising is negligible. The maths just doesn't math.

But to be fair It may be psychological. Eating is a very common coping mechanism and not taking care of your body is a common symptom of stress and depression.