Some folks are disputing that lower metabolism argument. Read the article...or even better yet, try the experiment on yourself.
I’ve always been underweight because I have hyperthyroidism. No other incentives for me to fast. My colon and I get along well, general health good. ;-) Even with my fun thyroid, at age 77, metabolism has slowed down. Women have it even harder as they age.
I’ll read the article, but based on observing my family, I am an advocate of simply maintaining a decent diet on a daily basis and being reasonably physically active.