Sign of an eating disorder ?

for ex. i ate a chocolate cake today at maybe 4 PM im now planning on not eatiing dinner cuz i ate it even though i excersized and burnt 300 calories?

Any compulsive behavior related to food could develop into an eating disorder. If you do this often - binge on foods, exercise to burn it off (esp. if you exercise daily, compulsively), and then skip meals AND feel guilty/fat all the time -- yep, eating disorder. If it happens every once and a while and generally you are in control of yourself and don't feel the need to compulsively work out/not eat/binge and purge, you're likely okay. Just part of the neurotic network of food-obsessives created by modern society. Oh joy.

just be careful it doesnt consume your every thought - its easy to get sucked in beleive me....

Doesn't sound like an eating disorder to me. I have an ED and when I first started noticing it I would eat only healthy negative calorie foods and I would feel guilty after. I would make myself throw up an apple cause I thought it would make me fat. I would also exercise constantly, before a shower I would do sit ups and push ups, and after I would run. I started to just not eat and I attempted to recover twice already, but relapsed. I would suggest to you to not worry about your weight and if you do, lose it the safe way. I've been hospitalized twice for my ED.

It could be binge eating disorder where you would consume large amount of calories from something unhealthy, then you starve yourself to compensate.