Hi I am a 15 year old guy and i used to weight about 150-160 about a year ago and now i weight 105 i have lost a lot of weight but i am extremely insecure about my body i still feel fat and everything but that is not the point, my point is ever since i lost so much weight I get mad easily and I am always cold and I get tired a lot. I go to the gym still and do about 30 minutes of cardio for like 2 days out of a week and do at least 100 curl up when i go too, and my diet is an 1000-1300 calories in a day what i basically eat is cereal with skim milk 3 times a day (corn flakes/special k red berry), 1 salad with carrots and broccoli and spinach and cumber, and 3 red apples throughout the day.so my question is am i healthy or not?

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Your low fat diet can kill you with regular cardio exercise. You need 2000 or at least 1800 calories a day, and also the fat is needed to create the hormones to keep your muscle mass. Enlarged heart can be a result of exercising with a low fat regimen. Your body makes hormones out of cholesterol and your body needs it.
Anorexia nervosa is less common in males than females, but it can often be fatal.