i have always allowed my beardie to eat as much as she wants. in give her greens every morning and blue berries as a treat but she will eat A LOT, her average day is a green bean with a couple blue berries in the morning along with 5-8 large adult roaches (say about 1.5-2" in size), then through out the day while I'm at work she pecks at her pellets and kale i leave out for her, at night before bed she will often eat another 4 or so roaches along with 15 or so meal worms. she will eat like this for 3 or so days, have a lighter day where she only eats a few roaches and maybe 50 or so worms but then goes right back to eating like a horse...
she is still growing and is gaining weight at a slow but steady pace. i figured she would be fat by now but i guess she is active enough. i figure she runs/walks about 1/4 mile a day around the house here, climbing and all that.