You are already overweight and fatty. You will have to change your schedule. This is the perfect age to modify your built. Here are few tips, it can bring wonders in your life:
1. You need to eat a lot of high protein vegetarian foods. These include dairy products (as long as you're not lactose intolerant), eggs (if you eat them), nuts, beans and legumes. Try to add a healthy portion of such foods to every meal.
2. You might want to try taking a couple of protein supplements in order to help you build muscle. Whey protein is the go to supplement. And creatine monohydrate is the next best thing to steroids, when it comes to building muscle.
3. As far as possible, stop eating rice, bread, rotis, and other starchy carbs. Impossible, I know, but try to keep these foods to a bare minimum. If you have a choice between rice and chappati, pick rice (the gluten free option). If you have a choice between polished and unpolished rice, pick unpolished.
4. Stay away from the so called "healthy" breakfast cereals. Don't eat cornflakes or muesli or Kellog's whatevers. Have a scrambled egg or a glass of milk or a fruit salad for breakfast instead.
4. Absolutely stay away from anything that has the ingredient "high fructose corn syrup" Just do not touch this. You'll find this in soft drinks and canned foods mostly.
5. Drink 4 litres of water every day. Not juice. Not milk. Not soda. Four litres of pure water. Keep a bottle of water next to you at all times, and keep sipping from it.
Also, I'm assuming you work out. You have to, otherwise no diet can help you.
Regarding the question about foods that prevent ageing, you need to eat foods with high antioxidant content. Green tea is one major source of antioxidants. So is red wine, if you drink wine. Citrus fruits have a lot of antioxidants as well. Eat plenty of fresh fruit and vegetables - not the juice, the whole fruit or vegetable.