Why is my bearded dragon so fat lol !!!?

hi i have a 23 month old male bearded dragon who seems to be a bit on the plump side lol... he doesnt eat his salad and calci dust so i gut feed his live food with it... i am feeding him meal worms and large locust and also the beatles that the worms turn into.. He tends to eat around 3-4 beatles a day and around 8-9 large locust twice a week.. He isnt very active though, he doesnt move unless i move him... i have been told that the worms and locust are quite fatty and to be given as a treat so am open to suggestions on what other food to give him that may be a bit better for his waist line lol