[Snickering Hound]

FDR either didn't know of it, or if he did know about it he didn't want to use it because it is a very restrictive diet.

FDR smoked like a dragon and drank like a fish up to the end.

He'd start with mixing martinis before dinner and continue until after 10pm.

[Pelham]

Yep. Which is why we can suspect he would have dismissed that diet even if he had known about it.