This is something that's a big thing with me. I come from a family where all of my mom's siblings (13 in all) are overweight and my dad's family has a history of heart problems. My little sister is overweight, my oldest brother is grossly overweight and in an attempt to prevent that, my other brother is grossly underweight (I believe he has an eating disorder, but am having a hard time getting him or my family to agree with me). I'm 21 and I have a feeling my metabolism is starting to catch up to me so I'm trying to ratchet up my preemptive measures. I'm in good shape (5'10, 178 lbs), but I want to stay that way. I was thinking about the things that I do to try and stay in shape, and these are some of what I came up with. 1. Daily exercise - I don't care if it's walking, running, biking, weight lifting or something else. It's important to stay active above all else. Someone else mentioned that if you consume more calories that you burn off, you gain weight. Someone correct me if I'm wrong, but I believe it's 3500 calories = 1 pound. As far as lifting weights goes, I really like doing it and I feel better about myself when I do, but I agree that its more important to do cardio work at first to speed up your metabolism. The two tips I have about exercise are: 1) don't compare yourself to others, if you aren't used to exercising, there will be people that can do things at a higher level, don't let that discourage you 2) exercise improves your mood and sense of self worth, I had severe depression in high school and exercise was some of the best medicine to get me through it. If running or walking does work, try biking, it's low impact on your joints and a lot of fun. 2. Deep fried food is the devil - I love eating fried food...don't know why, it's boiled in fat, dripping with grease and is awful for you. But it's still tasty. I try to avoid fried things at all costs. Breading on anything is a bad sign. Stay away. 3. Carbs are not a bad thing - I never bought into the Atkins diet. Your body needs carbs for energy and whole grain foods like pasta and wheat bread are also high in fiber. As long as you stay active, carbs shouldn't build up because they are the most easily available form of energy in your body. Granola (minus fun things like chocolate) are a good snack. 4. Fruits and Veggies rock - I try not to snack between meals, but if I do, I like to keep fresh fruit and vegetables around instead. I keep a bag of baby carrots around at all times. Grapes and prunes are also a favorite, but if you get carried away, they wreak havoc on your bowels. 5. Set goals for yourself - It's important to stay motivated, and one of the best ways to do that is to have something to work toward. I want to run a sub-6 mile and also be able to run over 10 miles. I'm pretty close to the first one, and I'm able to do between 5 and 6 miles. Make sure you set reasonable goals. You wouldn't start out by swimming the English Channel if you can't do a couple laps in a pool. I wanted to echo Beast Light's idea of drinking water with meals. This is something I do whenever I go to a restaurant. I don't like drinking calories, and it flushes out your kidneys. Trust me, the last thing that you want is a kidney stone. I had one about 18 months ago and it really messed with my health. I had weight-lifting and activity restrictions and was basically kept from doing anything active for about 3.5 weeks. And giving up or at least moderating your alcohol intake is a big thing. (I think) there are 9 calories in every gram of fat, but also 7 calories in every gram of alcohol. That's something I'm going to take very seriously this next school year.