Founder of Health Rising and Phoenix Rising
Low leptin levels have been previously shown to be associated with exercise addiction, fast marathon times, and training status in humans and also correlate with greater running speed and duration in mice.
Younger's findings suggested that increased leptin (or sensitivity to leptin) could be driving the fatigue, etc. in ME/CFS. Now a study finds that high leptin levels are associated with reduced endurance, motivation to do physical exercise, and reward.
Mice with reduced leptin signaling in the brain logged nearly twice as many miles on a running wheel compared with normal mice. The research suggests that falling leptin levels send a hunger signal to the brain's pleasure center to generate the rewarding effects of running.
"Based on these findings, we think that a fall in leptin levels increases motivation for physical activity as a means to enhance exploration and the pursuit of food," says senior study author Stephanie Fulton of the University of Montreal.
Interestingly, dopamine - which Miller's work suggests is in play in ME/CFS is in the ball game. Both factors apparently play a critical role in producing "reward". Miller was able to tie low reward to fatigue in ME/CFS.