As others have mentioned, you need to repair you metabolism, which means frequent (and plentiful) eating and frequent (and intense) exercise. A low carb diet would be a mistake: 1)the slow down the metabolism and 2) they make the intensity and frequency of work outs you need difficult or impossible. Look to eat a minimum of 6 times a day. Starchy carbs in the morning and after your workouts.
I reccomend three intense full body workouts each week (try nine total sets, three for legs, three for chest, three for back, all compound movements, all as heavy as you can handle without killing yourself reps 8-10). And as many long walks throughout of the week as you can (park at the back of the parking lot, if you do public transportation, get off a stop or two before you destination, take the stairs, etc.) Good luck