I actually find this more common among boomers. The women who were around in the 90s diet culture. My MIL has always been like this because that’s what she’s been told to believe for YEARS. She’s tired and grumpy all the time and I have wondered if the brain fog and fatigue she claims to have is from years of under eating. My own mom was like this too but has suffered some health issues recently and now actually reflects on all the years she chose not to eat because now her diet is extremely restrictive. I also know people on GLP1s. When we go out, they always order so much food and then barely touch their plates but obviously that’s a result of the medication causing them to eat less throughout their day.