Hummingbirds eat mostly small chain carbohydrates, sugar. However, while doing so, they also get a bit of medium chain carbohydrates, which they can also digest. While it is harder to digest, it has much more energy than simple sugars.
They sell unflavored medium chain carbohydrates in some health food stores, as energy drinks for athletes. So why not start adding more and more medium chain carbs to your hummingbird feeder?
Of course, it would need to be done slowly, over the course of several hummingbird generations. But getting that much extra energy might cause some interesting side effects. It would be like feeding a slim and trim athlete five thick steak and potatoes meals every day.
Since hummingbirds exercise a lot, they probably won’t become obese, but will likely make a lot more hummingbirds, at least at first. But then, again over generations, you might to see hummingbirds getting bigger. Giant hummingbirds.
We noticed most of our hummingbirds are overweight now, and walk around a lot instead of hovering...We noticed Their pointed beaks seem to have grown slightly longer, probably so they can just walk up to flowers and feed.