Just found this thread and wanted to shout my support and join in the share. I can relate to your struggle. Sounds like we had really similar childhoods. We're pretty close in age, I'm about four years younger. I was the "husky good athlete" growing up as well. Have been super self concious about my weight since probably 4th or 5th grade? Remember the "husky section" at department stores? I want to meet the child abusing sadist(s) who thought that was a good marketing idea. Hey assholes - NOBODY fell for that euphemism.
Stopped playing everything except basketball around 7th/8th grade, became less active, and January of my senior year of HS I had a primary care checkup and weighed in at 330 pounds at 6'3." Doctor prescribed me some appetite suppresants that didn't supress shit and told me to chew more gum. I was also diagnosed with hypogonadism (literally low T, lol) which I'm guessing contributed to my weight gain? My dad told me about someone at his work who lost weight on this diet called "Atkins" so I tried this newfangled low carb thing and after two weeks I saw real results. I was also on testosterone therapy which I'm guessing helped with the weight melting off. I was losing like 5 pounds a week which made it easy to be super disciplined and militant about diet. Didn't even have a bite of cake on my birthday that March. My friends still joke about me eating salsa with a spoon at our favorite Tex Mex spot. It also helped being 18 - I could fill up on as much meat and dairy as I wanted, never counted calories, and still kept losing.
That summer before my freshman year of college I had no part time job and nothing but time, so I'd get on my mom's exercise bike for 30min every morning and watch "Win Ben Stein's Money," then hit the Y in the afternoon to do some weights and run on the indoor track (I still remember 13 laps =1 mile). The day I made it a mile straight without talking a walking break was a big milestone. Nine-ish months later, in September of my freshman year at UT, I was down to 230. Lowest I ever got was like 190 which sounds insane now. I've been carb concious and pretty good about diet and exercise ever since, but I still have my struggles and the highest my weight has crept up is the 240's. I'm around that right now and trying to get back down to around 220.
Side note: in my early 20's I got off testosterone therapy and my levels returned to normal. Always been a chicken/egg mystery to me: with the weight gain/lowT/weight loss/normal T and what caused what.