He did not care for his body at all - it was just a cover, one of his many across lifetimes. The less he focused on his body, the less he depended on it. He was no Hercules, but had no health issues. His faith was immense, “if the Lord wants my body sustained, it will happen, why should I bother”… It was pretty scary for the less spiritually evolved or theoretical spiritualists who had not tasted the ambrosia of Grace the way he did (my mother thought he was a dangerous influence haha). He also did not take many students as most were interested in these physical feats/acrobatics rather than spiritual progress. He always said, “this is just one of the side effects of Divine Grace, the minute you lose sight of your goal and begin to focus on powers such as these, boom, you lose them”…
He relied on his mantra to derive prana which sustained him. I rely on my Neigong. Although, I am far from his level - so I still need to regulate my body mechanisms now and then, especially to remain grounded in my body and not flee astrally (I’ve talked before of how Dream rescued me on one such occasion).
I mean, I don’t think we can approach the Siddhas and their functioning via biology, the law of attraction, alien theories, or even most spiritual philosophies, etc. The word Siddha is interpreted to mean - “not following the rules of nature”