is my leopard gecko unhealthy?

I dont think hes unhealthy, i have two leopard geckos and they sometimes have trouble getting the skin off their toes. So what I like doing is getting a wet q-tip and gently brushing the skin off the toes (that is if he is old enough to be handled.) Also, make sure you have a little bit of moist moss in a moist hide so that he can use it to get the skin off.

As for the weight, try feeding him a few gutloaded wax worms. These guys are full of fat and leopard geckos LOVE them. They are commonly known as leo crack. Depending on how old he is, try increasing his meal intake. I usually give my full grown leo's about 5 meal worms every day and 2 wax worms along with the meal worms every other day. If that doesnt work, call up your vet, and they will know what to do.

Hope this helps! fell free to ask me if you need anything else!

You need to feed him a more varied diet, include meal/super worms into his diet and the occasional wax worm will fatten up his tail, but if his tail is really skinny i'd take him to a vet. Gecko's usually have trouble shedding the skin on their feet which causes them to lose their claws and sometimes their whole toes. Get a cotton pad and dampen it with luke warm water then gently rub it over his toes once or twice a day, never pull the skin off as it might not be ready and could get infected. Good luck!

that's all fine. In fact, mine is the same way. Just raise the humidity by spraying the tank with water. That way, it's much, much easier for it to get it's skin off.