I was/am an ectomorph, too. Around the time I turned 50, my basal thermostat decided to reset. Nowadays, I can gain weight if I eat lots of sweets, but otherwise my new set point seems stable. And it is, sadly, NOT ectomorph. LOL
Before then, I couldn’t gain weight no matter what I did.
Ann’s about at the age where she could experience the same.
Interesting. Thank you.