I'm 28 and I weighed 380lbs on January 12th and right now I'm at ~322. I believe I let myself go out of control because I was depressed. For a long time I wanted to die and figured I might as well do it with food if nothing else. I told my mom how I was feeling, and I somehow started feeling better ever since. It felt good to get it out.
Before, if I were to estimate the calories I was eating every day, it would probably have been close to 4000+ including the soda. I was addicted to fast food, and got drive-through pretty much every day. I also ingested a lot of alcohol on the weekends. I never exercised and sat in my desk chair all day at work, and then in another chair at home.
I slowly cut back. First, I cut out the drive-through lunches and started bringing my own food. Even if what you bring isn't healthy, it's going to be healthier and cheaper than fast food. I originally did this not because I wanted to lose weight but to save money. Then I figured, I'm bringing food, why not make it a salad? It kind of was a waterfall from there. I'm already bringing salads and eating less at work, why not make something healthier for dinner too. I'm already eating healthier, why not walk a bit. I dumped soda completely, but it was gradually as well. I went from 5-6 cans per day, down to 2 for a few weeks, down to 1 for a week, then to only drinking tea for the caffeine needs, and water otherwise.
Right now I'm eating 1200-1500 calories per day, and also walking 40-60mins per day. I might skip a walking day if my legs are especially sore or if it's raining outside or something like that, but for the most part it's 6 or 7 days a week for the walking.
I think a key thing that keeps me going so far is that I allow 1 cheat day a week to eat out. On these days I still eat 2000 calories or less. Sometimes my family wants to go to a restaurant, or I'll just go somewhere myself to get something that's sounded good all week long.
I use myfitnesspal to log everything and try to be as honest as possible. My iPhone tracks the steps and converts into calories burnt (although I feel like this is completely wrong, and gives me way more calories burnt than I actually burned - so I don't eat these calories back at all).
This is the lightest I've been since 2012 and the best I've felt in years. I know I'm still huge and disgusting, but it feels good and I hope to drop another 50+ pounds by the end of the year. My clothes are practically falling off of me right now. The best part is that after 4 months my stomach has shrunk and my legs/cardio have improved, so I don't think it's hard anymore. I'm not hungry all the time, I don't get caffeine/food headaches, my legs don't scream at me, I'm not out of breath doing simple tasks. I might have to get a gym membership soon and add some weights into the mix.
I know this turned into some kind of shitty blog post, but my point was to take it slow and let your body adjust, instead of doing everything at once or going cold turkey.