My lifestory is not the same as yours, so my advices might not perfectly fit your reality, but this is what I have to tell you:
- Try to understand why you're lying to the doctors. Sometimes (judging by myself) introspective people have this fear of talking the wrong thing or sounding weak/stupid, but the truth is that everybody makes mistakes, everybody gets sick, everybody has problems. You're doctor won't laugh if you tell him your problems. Don't be afraid of telling the truth.
- I used to be very careless about my weight. I didn't like to be fat, but as you, I didn't have any motivation to change my lifestyle. I had my "wake-up call" a few years ago, when I was in a party and I met this girl who was gorgeous - and I mean really really gorgeous -, but she was very overweight. The first thing that came to my mind when I saw her was "oh god, this girl would have any man she wanted if she took care of herself".
I started wondering... how many girls might have thought the same thing about me? How many opportunities I might have lost because I didn't care about myself? - just like the girl I knew she was a godess, but she probably didn't know that herself. That's when I started to lose weight and take more care about myself. I know the feeling, you think you're ugly because you're fat, but as you're ugly, you don't think that losing weight will help. But just like that girl was wrong, so are you.
I still have some weight to lose, but my social life really improved since that party. It is not just a matter of losing weight, it is a matter of self-steem. I have respect for myself because now I know how strong is my willpower/dedication. And of course, girls are way more friendly since then.
- The way I beat the overeating was as simple as possible: taking a piece of paper and writing everything I eat.
You'll get more family/friends' support as you keep going in your diet, because people will believe you - and so will you. The first time I denied a glass of coke because I was trying to lose weight, my friends were like "shut up, you gay! just drink that shit!". Now that they know my new lifestyle is for real, they all support me and even some of them are changing their lifes too, and at least part of that was because of me.
If I changed from "a fat and shy geek who used to see himself as the biggest loser on earth" to someone who's inspiring his friends and family to have a healthier life, you can do that too. You just need to give yourself a chance.