Firstly, there is no possible explanation for weak digestion while living on a frugivorous diet. Fruit generally digests within 20-30 minutes, whereas "standard" meals can take upwards of two hours. To say that a fruitarian suffers from weak digestion is sheer nonsense; were a fruitarian to eat meat on one occasion, then there surely would be a weak digestive response; not due to the weakened state of the person in question but because toxic, non-human filth had been placed within a perfectly cleansed shell.
The BeyondVeg website is purely a vehicle for the webmaster's negativity and shameless propaganda. If existing as a fruitarian is an idealist dream, then let us usher in the age of the idealist!