Yes it works and has a dramatic effect on people who are obese. The changes are remarkably immediate. I wasn't particularly fat (180cm, over 90kgs and climbing) but wanted to get down to low 80kgs. Took me less than 2 months (probably because I didn't stick to it religiously). But there was a noticeable difference in the first few weeks which just makes you want to keep going. But I'm almost 50. At 14.5yrs, unless you're morbidly obese, I'd say just start eating sensibly and exercise rather than the shock and awe of this diet. You are probably due for a growth spurt and your body is going through rapid changes anyway. I'd say wait until your late 20s. If you are fat then, then do it. But start eating right and exercising now! Good luck.