I'm fortunate (or unfortunate) I cannot eat enough to sustain my body mass, I find dumping or halving my sugar content and drinking GREEN TEA & Black coffee, will deplete your fat cell content.
Your body will contain fat cells everyone has a different amount in them sorry you cannot do anything about the quantity, but what happens is during exercise your body will draw on the fat from these cells, when you have depleted this storage your body naturally will replenish the cells, if you have too much sugar or huge amounts of fats and carbohydrates the body will use these to refill the cells.
Drinking Green Tea and proper Coffee without the sugar and cream will create a chemical and the stored fat will disappear quicker.
Food will always be a trial and error, bearing in mind you will use approx 1000 calories per hour when you run or cycle,
so may I suggest hitting a big breakfast and having a light meal for lunch and dinner. High protein (no greater than 25 grams per every 2 hours, everyone around you will thank you for that) and a slow release carb diets its all about getting that balance.
DON'T FORGET REHYDRATION
IN EVERYWAY I GET FASTER..
or you are getting slower