Data update: caloric deficit and shifting to a lower-carb diet

I discussed earlier changes in resting physiology during a caloric deficit and when changing macronutrient distribution (e.g. shifting to a lower-carb diet), see here: marcoaltini.substack.co…

In particular, after an initial increase in HRV, typically due to a large reduction in resting heart rate, I had seen a suppression in HRV with no change in heart rate, when shifting to a lower-carb diet. A similar, short-lived pattern, was reported in a study by Dostal et al.

Consistently with published research, my HRV data has also re-normalized after an initial phase in which there was a large suppression, possibly due to a combination of a reduction in blood volume (another physiological artifact that should not be overinterpreted as “positive or negative”, regardless of HRV), and an actual stress response

In terms of resting heart rate, it seems to be a good meter for caloric deficit, and nothing else. We can see how in resting heart rate the shift to a different macronutrient distribution does not impact the data, and how resting heart rate re-normalizes as soon as the caloric deficit stops

Protocol:

Data was collected first thing in the morning, while seated, using the HRV4Training app. This visualization, including daily data, moving averages, and individual normal ranges, is part of HRV4Training Pro (hrv4training.web.app)