It sounds like you expect meditation to translate directly to physiology. That's not somewhere I'd be going. I've never heard any modern sages even come close to mentioning anything like that. And they have put these people in MRI machines and stuff. I wouldn't suspect much would change in one's physiology in meditation. I mean, other than the obvious result of not moving. In fact, if I would suspect slightly higher rates of metabolism for someone really meditating over someone sitting still and lost in thought. When the default mode network is active in the brain, it's the easiest thing to do, so I would guess, a low energy requirement. When you are paying attention to each observation in each moment, that would seem to require more energy. Since the brain is a huge consumer of energy on a pound for pound basis, slightly more energy might be required when allowing the senations of the moment to fill your mind. I used to think meditation was dreamy and effortless, but the more I practice the more obviously wrong I was.