@leebrown5, Garmin says Body Battery is an estimate based on HRV, stress, sleep and activity. It isn't measuring MOTS-c or mitochondrial output. I can see why you'd watch it alongside symptoms, but a change in that number alone can't tell you what caused it; sleep and activity can move it too.
The MOTS-c research is genuinely interesting, just more specific than many online summaries make it sound. In a 2021 paper, exercise raised the body's own MOTS-c in ten men. In separate experiments, giving MOTS-c to mice improved their physical performance. The men weren't given MOTS-c, and the study didn't test fatigue improvement in people with ME/CFS.
One person who posted a 20-day account described better endurance and recovery, but also itchy welts and bruising. They were using other compounds as well, so the cause of the changes is hard to separate. Your tracking adds a real-world observation to this discussion, even if it can't settle that question by itself.
I contribute to PeptideWHY. Hey, check out this article if you want the study and that user report in one place:
https://peptidewhy.com/materials/mots-c/ . It shows which findings came from people and which came from mice.