It's not a lack of food, at least in the US.

Go down to the Social Security office (and you won't find the gray haired people there...you'll find the average age under 40 and over 200 lbs...) and just observe.  

Please go take a look.

https://4.bp.blogspot.com/-CkjDiu1DQyo/VyFl5tLCx9I/AAAAAAAAJ2I/IMCw6o32LAYf0YtcIZcRwx5J26Z7eDjyQCLcB/s1600/SS%2Boffice.jpg