1 Eat in moderation, stay away from mc.Donald's and other fast food the only thing I would eat at mc.d's is their filet of fish. If your want to eat before bed eat a salad( it is very low in calories).if you do need to cheat on your diet try to wait until the earliest part of the day so you have time to burn it off before bed.
2 if your lifting weights do more reps for less weight. 1st set 12-15reps, 2nd 10-12reps, 3rd 7-9reps. I used to work out pretty much my whole life on and off during the year, but my job is very physical so I have to save my body..... I'm not trying to sound arrogant but I'm 46yrs old,5'4",and 140lbs and still have abs and a better toned build than most in their 20's.
you don't need to go on one of those dumb unhealthy no carb diets or what ever, just clean your diet up a bit!!!:)