It is very important to keep our dog at an adequate weight. Unless your vet advises otherwise, you should try and keep your dog in the weight-range typical for his or her breed and gender.
Here we present a chart of the weight distribution for Shih Tzu dogs. The weight of a typical female ranges from 5.2kg to 8kg and that of a male from 5.4Kg to 8kg. That is, 11.5lbs to 17.6lbs for females and 11.9lbs to 17.6lbs for males.