Leo Sher, M.D. 

A research report, “Fasting for 20 h does not affect exercise-induced increases in circulating BDNF in humans” has been published in the Journal of Physiology online ahead of print (1). Researchers from the University of Otago in New Zealand report that 6 minutes of high-intensity exercise on a regular basis can prolong the lifespan of a healthy brain and delay the onset of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. High-intensity exercise increases the production of Brain Derived Neurotrophic Factor (BDNF), a protein involved in the biological mechanisms of memory, learning, and brain plasticity, which could safeguard the brain from age-related cognitive decline.

To study the impact of fasting and exercise on BDNF production the researchers compared the following factors to investigate the isolated and interactive effects:

• Fasting for 20 hours,
• Light exercise (90-minute low intensity cycling),
• High-intensity exercise (six-minute bout of vigorous cycling),
• Combined fasting and exercise.

The authors found that fasting for 20 hours caused a 9-fold increase in ketone body delivery to the brain but had no effect on any metric of BDNF in peripheral circulation at rest. Prolonged (90 minutes) light cycling exercise increased plasma- and serum-derived BDNF irrespective of being fed or fasted and seemed to be independent of changes in cerebral stress. Six minutes of high-intensity cycling intervals increased every metric of circulating BDNF by 4 to 5 times more than prolonged low-intensity cycling; the increase in plasma-derived BDNF was correlated with a 6-fold increase in circulating lactate irrespective of feeding or fasting. The authors concluded that compared to 1 day of fasting with or without prolonged light exercise, high-intensity exercise is a much more efficient means to increase BDNF in circulation.

Reference

1. Gibbons TD, Cotter JD, Ainslie PN, Abraham WC, Mockett BG, Campbell HA, Jones EMW, Jenkins EJ, Thomas KN. Fasting for 20 h does not affect exercise-induced increases in circulating BDNF in humans. J Physiol. 2023 Jan 11. doi: 10.1113/JP283582. Epub ahead of print.