An Australian doctor observed similarly. His origination? Most people check out of hospital more malnourished than when they were admitted!
And this matches my story. When I was about 60 I had keyhole surgery for a hernia. Nothing to eat from 10 pm the night before till I came out of the anesthetic about lunchtime the following day. Ravenous!
I asked my wife to get me something to eat. She came back with two white bread and cheese sandwiches. I inhaled them. Of course they did absolutely nothing to quell my hunger so she went to the cafeteria, looking for something healthier.
The best they had was a sausage roll!