You say you suffer from depression, but you're only 15, an age when life just goes quickly from stage to stage. So I wonder if you've diagnosed by a psychologist with depression and, if so, are you in therapy for it? Eating disorders are common at your age. I'm guessing you're a thin person naturally, and as long as you're healthy you don't really need to eat a lot of food, but you obviously know you need to eat enough nutrients -- noticed I said nutrient, not food. That's why the emphasis on a balanced diet with whole grains, enough protein for muscle development and brain development, enough veggies and some fruits for the antioxidants that protect our cells and protect our bodies from inflammation and protect our immune systems, which is why the huge emphasis on eating your green leafy and colored veggies. So I'm guessing you know about this. Again, feeling sad or unhappy isn't necessarily a mental illness, but when it goes on a long time it can become one and eating disorders can affect your health in ways you might not notice for many years. That's why I suggest, if this isn't something you can fix and you know it's not beneficial for you, then seeing a therapist who can help you figure it all out is a good place to start trying to fix it.