Eats like a Bird?

Saying that someone eats like a bird indicates they do not eat much at all, butthe saying has no basis in truth. Some birds eat huge amounts of food, relatively speaking and depending on the kind of bird. Try being like a chickadee and eating 35 percent of your body weight. Not happening.

Different birds have different needs; they were designed for variety. Some like seeds, others like carrion (interesting ecological niche to be on the Clean-Up Committee), insects, and as expected, worms. There are some that have surprising items on their menus.

To say that someone eats like a bird is a silly way to say they do not eat much. There are some birds that have very surprising things on their menus, such as the red-bearded bee-eater.
Red-bearded Bee-eater, Wikimedia Commons / JJ Harrison (CC BY-SA 3.0)
Bee-eaters have a way of rending stingers ineffective while feasting. This means that they don't have to deal with the venom that should kill them! Then there's the roadrunner that has a taste for rattlesnakes... These show the work of the Creator, not Darwinism.
But are the diets and dining of birds really so inconsequential and insignificant? As ICR’s Dr. Frank Sherwin has repeatedly documented—with huge frigatebirds and tiny hummingbirds—the diets and eating habits of birds can be fascinating. In short, our Lord Jesus Christ feeds His winged creatures in wondrous ways—“hidden in plain view”—that exhibit His clever and caring genius.

You can read all of this short but interesting article at "Eating Like a Bird."