Board Thread:Versus Debates/@comment-34656247-20180726110937/@comment-26107879-20180728120128

Already listed his weight at 70. But I clearly pointed out all non sick men in their prime weigh over 140 pounds. Therefore, Hiruzen and Danzo, who weigh extremely low; would be at that weight range in their prime. Choji's weight range is about 140 as well. Thus Hiruzen in his prime would have enough calories to perform some of the Akimichi arts.

Also it was stated multiple times that Hiruzen's abilities were deteriorated due to his old age. His Chakra, his speed, strength, etc. Just look at his profile. The answers to everything are already there if you need them.