I'm late to the party...been doing my own thing since last September and down about 60 lbs (285 to 225 - I'm 6'0") I've cut my body fat % from 43% to 21.2% at a check in on July 1, aiming to be under 20% by end of July. Here's some things I have learned:
1) My diet could best be described as some kind of lazy keto/paleo mix. I'm avoiding most anything processed. I try to focus on lean proteins, fresh vegetables (cooked in a variety of ways), some fruit a couple days a week, and very limited on grains. I don't do wheat anything because I found out I had Celiac's last year. Ultimately, I eat more and feel better putting clean stuff in my body.
2) Limited/moderate drinking consists of the occassional bourbon or vodka, sometimes with soda water and lime.
3) Avoidance of sugar is key for me. Just spurs all kinds of crazy cravings. If I'm dying for something sweet, I'll try some fruit. I have a horrid sweet tooth.
4) Hydrate, hydrate, hydrate. It's the prime carrier of toxins and other yuck out of your body.
5) I'm doing 3-4 hours a week of Camp Gladiator, which was tough to start but has become a drug for me. There's tons of different fitness options, getting out and doing something/anything is a key part of transforming your body.
6) Specifically to address the quoted point above, after starting exercise, I lost 10 pounds quickly and then gained 4-5 pounds that stuck around for about a month. But my victories were not happening on the scale. They were happening on my measurements. You're going to gain a little muscle weight when you start working out, don't get frustrated.
Before I got serious after visiting my doctor last August and having her inform me I was pre-diabetic, my blood pressure was not coming down despite taking 3 different medications, and she was going to drop some vague and frightening hammer on me if I didn't make some wholesale changes.
I've been over 250 lbs since my freshman year of college and have struggled with diet and exercise my whole adult life. The key for me has been finding something sustainable and relatively enjoyable that becomes a life change instead of a 30, 60, or 90 day challenge.
I salute all of you for committing yourselves to do better and be better!
TL:DR// Find a healthy eating regimen that works for you, exercise, and hydrate.