Most will probably tell you to screw my advice here, but I gain fast (I will put on 10lbs a month if I don't get to the gym, I cap at about 240lbs though and I am 5'10.5") and I know how to lose it fast. You are a oldy here and a respected trader so I will elaborate my story.
What works for anyone, may not work for you. You live and learn. However; if you stick with 3x a week and try to pretty much kill yourself (not literally) in 30-45 a pop chances are one day you won't have to put what you eat and drink under a microscope.
You want to not push yourself too much to get an injury. That's one of the biggest deal breakers. Expect to feel a ton of pain though the first 1-4 weeks due to lactic acid. Maybe a few headaches (I get a migraine 25-50% of the time after a long layoff every time I start leg presses or squats for the first 6 or so cycles).
Dial in your diet. For me though my diet is really about 10% of my deal. I can practically fast and stay heavy only to start getting very sick (I never get colds even usually). Dieting by itself doesn't work for me. However; if I don't eat right I feel it in the gym.
One of the biggest diet things for me is to shed all soda. I only drink diet coke anyways, but that stuff bloats me like I gained 10lbs very quickly and I love beer which doesn't affect me like that.
Also at your age, I'd seriously recommend a testosterone test and the other hormones that relate to it. I had low-T and never knew because I still had a high sex drive.
When I was young, I was able to lose 86lbs in 90 days. (crash diet and over-training which I don't recommend for best results, I lost 25lbs of muscle I probably will never get back, but I kept that weight off 10+ years).
I had a bad set of luck since around 5-6 years ago. I have a high pain tolerance. Around the same time I shattered my right elbow and didn't even realize it. I started putting on weight. I skipped lifting, tried to run, bike, etc. Soon even picking up a cup became painful. All that chronic pain I was ignoring messed up my hormones.
I recovered the first time around 4 years ago only to get back in the gym and healthy again. I was doing squats and two kids pushed my bar out of their way while horseplaying in the gym. I couldn't clear it from my left arm and it torn my labrum. I didn't know it then...by six weeks later I couldn't lift my left arm much without major pain the next day. Running and biking even caused this. Insurance wouldn't authorize an MRI. Had my surgery and within 6 weeks I was back in the gym. Fast forward to my signature.
dialed it all in and did it. My diet was OK at best. No fast foods, but I didn't turn down a steak or a beer. I am not a dessert guy though unless it's the chick I am with .
Now in March I tore my right bicep at work. I recommend anyone that does this and doesn't just want to take a 2 year vacation from work (I missed no work), lie and say you fell at home.
They pushed me out beyond non-high risk surgical repair. Then, I finally got them to approve seeing my surgeon who fixed my shoulder. He was pissed, but there is no way out of it. Workman's Comp is no-fault, you can't sue for damages; all they have to do is provide 'adequate care'. My surgeon said the best I am going to get is let my arm heal and hope it can bond where it lies. Either way though he said I may never really improve from what I am left with. I took the chance and just have been babying that arm for the last several months. In August I was told I can return to the gym. My arm is basically F'D cosmetically, but I came in with a ton of bicep strength so that helps me a lot. With all this drama I have been in I haven't been able to train, on top of that I have some certifications I need to complete. At the same time I was going through a divorce, moving someone I fell in love with and her children here, and more problems.
I am hoping to return to the gym in January.
I am about to reset all that.
I'd look into supplements on a weight-loss too. Vitamin B esp 6 and 12 works well for me. C is great. A and E. Vitamin D and more.
Not going to embed my images since people here get irate
but this is me at 224lbs on 9/24/2012
http://imagecdn.bodybuilding.com/im...RByYtBByhzdeXPCTlKULVrspZCWIlJEANZk-610xh.jpg
And me at the end of December 2012
http://imagecdn.bodybuilding.com/im...XOHLBGPhGGlZmQlOISbKwxrvTGumnOcSQYe-610xh.jpg
In the end though, don't do it for your wife (I have found they love you regardless) or anyone else. If not for yourself, you will fail unless money or some other commodity is attached.