if you know you eat unhealthy stuff in excess when depressed, have you tried not buying the unhealthies in the first place, if they are not at hand, you won't be able to eat them! try stocking up on healthy snacks like dried seaweed, or popping corn, or simply chop up some cucumber, carrots and bell peppers into batons and nibble on those instead. i never keep chocolate or crisps in the house, that way if i want any i either have to go buy some or make crisps myself which is often enough to put me off the idea of wanting them! dried seaweed is great as you can eat loads and still only consume a hand full of calories but loads of iron and stuff thats good for you! chinese rice crackers are good too as they have only a few calories and give you the crunch that you sometimes crave!