I went from 270 to about 170 over the course of five years, and I'm older than you. I personally don't give a shit about stretch marks--I get that some people do but I can't really relate to that particular anxiety so I'm just going to respond to the loose skin concern.

I can relate to fretting about loose skin, though. It was one of my real fears as the weight started to come off. I don't have ripped abs and I'm not sure that I'm capable of ripping them for a number of reasons (age, genetics, demands on my time, etc).

About a year ago I had a little loose skin and a little pudge and was in a position where I looked pretty good in clothes and like a garden variety skinny-fat dude shirtless. I was afraid this was a permanent condition, but there was no way that it would have prompted me to have surgery (some people might have chosen that option and I can see why, especially if money were not any kind of issue).

About a year later, the loose skin has tightened. I'm not a Greek sculpture (though I've been going hard lately because I'd like to get close to there) but I have a respectable V shape going and don't feel even a little self-conscious shirtless.

I think everyone in this thread is constructing their own image in their mind of what you look like, but you're the only one who actually knows. It's possible you're grossly overreacting to the actual situation and it is either livable or improvable with a little work and time. In all candor, though, it's also possible you've really fucked your body up and you have a LOT of loose skin that isn't going anywhere without surgery.

So the first thing you need to do (which a lot of people who have never gained and/or lost a ton of weight might not understand because they've never seen their body change dramatically) is get a fucking grip and figure out how bad it really is.

People who can take off a lot of weight (or write a book or make a ton of money or do anything else that requires an almost obsessive drive) often misjudge themselves and their situations quite badly. Cuts both ways. We keep lying to ourselves that we're not getting fat until it's too late, then as we take the weight off we drive ourselves by not being satisfied.

After a good workout, when I can see my abs and obliques and pecs it feels fucking fantastic; a couple of hours later when I look at my body without a pump on and remember how far I still have to go it sometimes makes me wanna scream like Frank Black whacking his thumb with a hammer.

So first things first, find some way to get yourself grounded and assess your own body as rationally as possible.