1yr old boxer seems really skinny and over anxious at times

Question
Hi, first of all my boxer is up to date on all shots, eats healthy, hes 1 year 1 month old. Hes a white boxer (idk if this is relevant or not, he is very active and playful. He does weigh about 70 lbs, but the back part of him looks very skinny, like his ribs show and everything. He does not have worms, he is not sick. I'm just wondering when he should start to thicken out and not look so skinny. It kinda worries me!
My next thing is when I give the other dog any kind of attention he gets really anxious-like and panics.  He is alright as long as it is not me giving her attention, I try to give both of the attention at the same time and he just kind of pushes her out of the way. Is there something I can do to help with this? It gets to the point that sometimes hes crying and drooling and  forcing himself up on my lap if I am even petting the other one.

Answer
Hi! Boxers go through these stages that will drive you crazy. one day, they'll look nice and filled out, the next they look so skinny it's pitiful. Your boy is still growing some. They can grow until they're about 3, not getting taller, just filling out. Make sure he's wormed and on a good food. You may need to feed him more right now, especially if he is going through a growth spurt. Offer more food, and see if he's interested. Some Boxers are thin looking, and there's nothing that can be done, but if your boy was filled out nicely before, and is now just getting a bit skinny, then he'll most likely pick that weight back up. As for his behavior, Boxers are known to be jealous. Get someone else to put him on a leash and make him sit. While you are petting on your other dog, have the other person praise your Boxer when he doesn't act up. Get this person to distract him with treats and such.While you are petting on your dog, put your boy in a sit, and ignore him if he tries to get pushy. Good luck, and let me know if I can help with anything else.