I just turned 19, I'm 6'3", and I weigh 340. I'm hoping someone on here could give me some real insight to getting my weight down. Basically, according to my doctor, with my frame, I should weigh around 210-240, no more. I was about 270 out of high school, but 8 months later, I've gained 70 pounds. I have joint problems with my knees, and I'm at risk for diabetes as it runs in my family. I've tried getting a handle on my diet, but I can't find anything that seems to work on a good basis rather quickly, so I slack off and quit. I'm not planning on trying any weight cutters or ephedra, I'd like to do it by diet and exercise, maybe the help of some supplements. We've got a rather large GNC in town here, and if need be, I'd be more than happy to see about some natural weight loss things. Here's the details of my diet as is. I at one point in time was consuming between 1/2 - 1 gallon of water a day, but that was mostly as a means to flush my system from all the caffeine I consume. Now, I rarely get 20oz a day. I eat generally two meals a day, fast food for lunch, whatever I can srcrounge up for a large dinner around 7 at night. I'll occasionally snack on stuff, but it's mostly junk food. I drink maybe 3-5 sodas a day, which is pretty bad I know, but that tends to be all I have access to at work. What I'd like is some input from you guys on a decent diet that will help me lose weight fairly quick, nothing abnormal or such. I know you all recommend cardio, but with my knee not being the most sturdy, I'd like to get off maybe 20-30 pounds before I do any high impact cardio, seeing as how I'm sure my weight has a lot to do with my problems. Any help?