This is a remarkable post in a lot of ways. First, congratulations on getting down from 245 to 210. I personally know how difficult that is and it is something to be proud of. I also understand the wish to get even lower. It took me a long time to get down to 200. But once there it became a bit easier. For one thing, I was no longer carrying all that extra weight around. (At the moment I'm suffering a set back and at my age it is going to be very difficult to get back to where I was a few months ago, but I don't want to make this about me.)
I don't know enough about you to be a huge help but i can share with you some things.
As you suggest, there are different levels to this. On one level it is fairly straight forward… You want to loose body fat and it is important, in the process, to gain some muscle. This can be approached somewhat scientifically though proper nutrition and exercise. It is said over and over again, it is 80% diet and 20% working out.
But the real hurdle (IMO) is psychological and it is complicated. I don't know about you but I am an *emotional* eater. That is, when I feel stressed or feel my life is out of control, I tend to eat more and not only more but things I shouldn't. I can, for example, wipe out an entire New York cheese cake or, alternately, two pints of ice cream, IN ONE SITTING. This is *emotional* eating, it has nothing to do with nutrition, even hunger, really, and everything to do with stuffing down my feelings or, put another way, trying to satiate my fear and anxiety with food.
This can be a real Catch 22 when dealing with self-image. If I don't like myself, don't like the way I look, feel frustrated or anxious due to real-world stress (for you, perhaps schoolwork), etc., then I'm likely to eat more than I should *and* more things that aren't healthy--thus *perpetuating the negative self image*. It can be a vicious downward spiral. That (and a slower metabolism as I aged) is what got me up to 250# to begin with. (Prior to age 50 I had always been a slender guy and could, and did, eat anything.)
The first thing I did was begin doing a ton of research about proper diet and nutrition. AND I began walking, daily. I learned that I could eat as much greens and vegetables as I wanted and pretty much as much meat and eggs as I wanted. What I couldn't eat was sugar (in all its forms except whole fruits) and wheat (in all its forms). Everything else could be in the diet at times but only in moderation. And I had to force myself to drink way more water than I normally did.
So I set myself the goal of eating good, healthy food. No packaged or canned or bottled food (like sodas and stuff). It had to be clean and healthy. Now, the thing is, I also had to be realistic about this. I decided if I could focus on this kind of diet and stay within it 80 to 90% of the time, that was good. In other words, I reasoned to NOT beat myself up when I ate something I knew I shouldn't. I also had to reasonably accept, however, that every time I went 'off the book' I was making it harder for myself.
So what I'm saying here is that I had to find a kind of emotional balance point that was realistic on the one hand but not overly permissive, either. I understood this was a long-term, in fact LIFE TIME, thing. I think for younger people, provided they focus on it, it can be done relatively quickly but at my age, it takes longer and is much more difficult.
You're asking about how to deal with self-image in a very broad way and this is a very interesting question. On one level, we have to accept that genetically we are what we are. You (so far as I can tell) are a big guy and probably *always* will be. BUT, can you become a "better" you?
Or, put another way, can you fulfill your FULL genetic potential? This is a very interesting question when you think about it. I believe you can, that anyone can, IF they really focus on it and are realistic about it. Someone once pointed out that if you want to look like _____________ (fill in the blank with whoever you see as hot), then the best way to do that is to have HIS parents! But you don't have his parents, you have yours and that isn't anything you can change. However, the fact is, most people do NOT eat right, they don't exercise, they don't really focus on their physical (and psychological) potential and, consequently, (unless they are genetically gifted to have a low body-fat percentage), are *always* going to be carrying more fat on their bodies than they need.
I know this is long and I don't know if it is helping. From what I can tell by your face pic, my sense is that you are a naturally attractive young man. Can you be more so? Yes, of course. And being "attractive" is a combination of physical appearance, style, personality and what I call "presence." The latter term has to do with you being IN yourself, aware of yourself in a positive, present, focused dynamic way. This (IMO) is possibly THE most important thing. That is, sure, I can walk into a room with a bunch of guys that are buff, low body fat, and find them "attractive". But the ones that *really* get my attention may *not* look like that at all. The ones that really get my attention are guys who are self assured, project confidence and other qualities like kindness, intelligence and so on. Such a man may not be young or model quality, but he has *something* from within himself that outshines all that. It is his personality, yes, but it is more than that. It is a whole quality of energy that he manifests through his body and personality.
So, sorry this is so long winded. I empathize with your struggle on all those levels. Building up one's self-image and confidence, especially after growing up in a social environment that was constantly putting us down (for whatever reason), is an enormous challenge. But think of it *as* a challenge, not a burden, not a task, not a "chore" -- but an exciting possibility. Our attitude towards our lives really determines the outcome on SO many levels. This is one thing this old man has learned.
I hope this helps and I wish you the very best -- and I for one strongly believe you can achieve it -- probably far more easily than you currently imagine.