Yes that site may require a membership but if you want I can help you work out a diet to get you were you want to be. If you are truly close to 20% bodyfat you need to get that down, alot. I would never recommend going that high unless you are in a sport that requires you to be very large. IE linebacker, super heavy weight powerlifter, super heavy weight wrestler, etc.
What you need to do is first hone your diet. Pick one that is right for you. They all work for some people but they don't all work for all people. Once you get your diet straight get your cardio in order. Do at least 45 minutes a day at least 5 days a week. Aim for a heart rate of around 140 for the entire time. If you really want to lose the fat fast do as I said and take a long walk, and hour or more, everynight on top of your cardio. If you live near the beach take long walks on the beach. Make it fun. Take your girlfriend with you.
To keep your muscle mass and maybe even add some more in the process lift hard and heavy 5 days a week. I prefer breaking it down like this. Legs, Chest, back, rest, shoulders, arms, rest. Do abs everyday, do calves at least every other day if not everyday. Do compound exercises with as much weight as you can handle in a pyramid 15,12,10,8,6(reps). Pick about 3 exercises for each bodypart except arms and then maybe 2.
Getting bigger muscles at 20% bodyfat will only make you look better in clothes. When you get to a point that you are proud to take your shirt off start upping the calories until you start adding muscle. If you are truly 20% bodyfat at 217 pounds, 16 years old, and 5'9" than you are truly genetically gifted for bodybuilding. That means at 16 you would be 173.6 pounds of lean weight. You could compete at 5% bodyfat with a weight of about 182pounds, as a teenager none the less. If you continue training hard and add 10 pounds of lean weight you could still compete in the teen class when you are 19 at roughly 220 pounds. If you continue and add just 5 pounds a year after that by the time you are 25 you could compete at 242 pounds at around 3% bodyfat at 5'9". In other words a genetic monster.
Get in touch with me PM and we will get you started.
Hayabusa