I'm trying to lose weight and need help

Hi. I'm 16 and 5'3". I weigh 185 pounds. In the past two years I've gained 40 pounds. I know this isn't good and I've struggled with a lot of depression and other issues. I've always been worried about my weight and I'm very upset I let my weight be this much. I want to lose to be healthy because type 2 diabetes runs in my family and they've already said I'm at risk. I've considered becoming vegetarian because I don't like meat that much as it is. Would this help me lose weight? What about the paleo diet?