By Diarmuid's reaction he thinks his answer must have been the right one.

"Okay," he replies to the offer, but he wonders if trying different food is something he needs to accomplish. It can't hurt, at least.

He returns his attention to the tray and continues to eat and drink silently, feeling himself getting more tired instead of feeling like he's getting more energy, and briefly considers the fact that HYDRA's way of feeding him seemed more efficient. He guesses that living in a way more like other people comes with its own set of weaknesses.