What is not clear from either is whether the participants abstained from all liquids - even water. Anyway it seems that fasting diminished balance skills, which is a concern.
Fasting is always easier if you are on a low carb diet and running on ketones, so I wonder if that would be an issue - the average person running on sugars needs constant topping up or else blood sugar issues can have effects. I wonder if hypoglycemia affects balance?
In any case it is something to bear in mind if you are experimenting with intermittent fasting.
The effects of dietary fasting on physical balance among healthy young women.
ABSTRACT: BACKGROUND: The study examined the effects of dietary fasting on physical balance among young healthy women.
METHODS: This study undertaken involving 22 young healthy women (age=22+/- 1.5) using a within subject counterbalanced 2-week crossover study design. Participants were asked to refrain from consuming any food or beverage for 12 hours prior to the fasting trial and to maintain their regular diet for the non-fasting trial. Measures included: a background questionnaire, 24-hour dietary recall, and functional reach and timed single-limb stances. RESULTS: Fasting resulted in significant declines in functional reach (p<0.01), and ability to balance in a single limb stance with eyes open, on both the dominant and non-dominant legs (p<0.01 and p<0.01, respectively), and with eyes closed on the dominant leg (p<0.01). CONCLUSIONS: The findings have implications for athletic performance in younger individuals as well as emphasizing the need for health education for young women to avoid skipping meals