It might be that since you previously have been fat your receptors' sensitivity is screwed up, it takes time to adjust those issues.
One of the first things to avoid is to eat frequently, which usually is a very strong habit in obese subjects, I mean putting anything in the mouth, not just having a meal.
Usually obese people are convinced they actually do eat very little food, in fact it might be true that they do eat quite small MEALS but they are always munching on something all day long, that causes continuous insulin release which leads to receptors insensitivity.
Eat your food at meals ONLY, eat a lot of food if you like but between meals NOTHING has to enter your mouth but water, period.
Two meals a day might be a good strategy, especially if the big one is immediately after training and the small one contains no carbs at all but some veggies, it might require a relatively high fat diet to feel comfortable which such a kind of nutritional plan.