If it was a simple sugar and not a complex sugar then it's very possible the fly could consume the sugary water, metabolize it, and fly again in only a few seconds. Insects are substantially different in how rapidly they can break down carbohydrates (sugars) compare to humans.

Yes fly like sweets too much which become a source of energy for them.

I once saw a science documentary film of a house fly tied with a string to a stick, and flying around and around the stick set upright, and then it stopped flying; so the laboratory demonstrator brought sugary water to it, and it sucked the liquid and immediately started flying again.

Now I am wondering, is that documentary film genuine, or there is a long time gap between the stopping of the fly in flying and the resumption of its flying upon sipping in the sugary water.

This was a demonstration of energy consumption, how static energy is transformed into kinetic energy.

Looking back, I think the experiment was deceptively rigged up; there is no such thing as an instant energy drink of sugary water, not for humans and not for flies either.

Try this experiment: You go jogging and get so tired you have to stop and rest, so instead of resting you just drink some sugary water and presto right away you can run again.

Not that simple because it takes time for the sugar to get changed from static energy to kinetic energy in you, so also I think with flies.