hi doctor, why my dog is always hungry? he's a 2.6 years shihtzu male.. whenever I get out of my kitchen he would check my hands if I'm carrying any food, whenever I have any fruit or snack, he would bark continously at me.. I usually feed him an egg with veggies in morning, a snack usually a sweet potato or a carrot around 3pm.. and for dinner I serve him 4 tablespoon kibble.. am I feeding him less ? his current weight is 8.5 kgs and tends to gain weight..