You can't outrun a bad diet. Try to make some small lifestyle changes. Smaller breakfasts of oatmeal or plain yoghurt and some fruit. Cut sugar out everywhere you can, no more energy drinks and snacks while studying. Try to cut back on carbs, and no going for second helpings. Look for healthier options at your school cafeteria instead of that slice of pizza.
Personally I've had a lot of success with intermittent fasting and a 30 minute walk every day.