You're focusing on the overweight side of the ledger, causing your character judgement to kick into gear. Controlling your weight can be difficult without moral failure. When I was 14 I was desperate to gain weight (5'10" 128lbs) so I was eating nearly 3,000+ calories per day. I was lifting weights a few times per week for maybe 20-30 minutes but not much other exercise. Over the course of 5 years I gained a grand total of 19lbs. Weight gain is definitely not a simple calorie intake vs calories burned formula.