No, he didn't lose too much weight; the shar-pei is a wrinkly dog, known for his extra-loose skin. His fur may be short, known as a horse-coat, or slightly longer, for a brush-coat. Regardless of the kind of coat he has, the shar-pei doesn't shed much, other than his seasonal shedding.
Shedding With the Seasons
On a day-to-day basis, the shar-pei sheds very little, but he is a seasonal shedder. In the spring and fall, he'll drop some of his hair when the change in day length becomes noticeable. Your shar-pei may not look quite as handsome during his seasonal shedding spell, taking on a bit of a mangy appearance, however a good brushing with a rubber comb will help his coat bounce back to life. As a rule, the shar-pei doesn't have high-maintenance grooming requirements. A weekly brushing with a grooming mitt or light bristle brush usually does the trick for him. He doesn't need to be bathed much other than before and after his seasonal shedding, unless he gets unusually dirty. If you choose to clean his wrinkles, make sure you dry them thoroughly so they don't become infected. If you're unsure whether your shar-pei should have his wrinkles cleaned, talk to your vet.