Hi, Fuggles. I am just curious what makes you think that. I don't believe that is true - would depend on how sick you were, for one thing. . . tho it would certainly help. But, to answer your q, avocados are fine.
Avocados are a great food and are a good source of healthy fat.
I'm not sure you could get rid of Candida with exercise only, but anything is possible. If you used the Water Cure in conjunction, maybe, but I don't have any (first-hand) experience with that.