As much as I love Varga Llosa as a novelist, it is fair to be cautious about him as a source of history.

I found a PDF of a Harpers article by Vargas Llosa with a slightly different title but the same claim and (surprise, surprise) no source cited: http://archive.harpers.org/1990/12/pdf/HarpersMagazine-1990-12-0007669.pdf?AWSAccessKeyId=AKIAJXATU3VRJAAA66RA&Expires=1429075051&Signature=KWgf%2F8zIrXLkKIy8sAJIFi4t9Zo%3D

Peruvian historian Maria Rostworowski de Diez Canseco talks about the system several times in History of the Inca Realm (https://books.google.com/books?id=PfO9_ohMYQQC&dq=abolition+of+hunger+under+the+inca&source=gbs_navlinks_s).

The short answer is that yes, in the places where the Inca system was implemented the State helped distribute food and goods throughout the empire in such a way as to satisfy the primary needs of most peoples. In fact, she goes on to say, the way the Inca often expanded without military conquest was that their system was so efficient people wanted to join. It was a major selling point.

In her conclusions, under the heading Final Reflections and starting on page 221 of the link provided above, she states that the distribution system itself was part of an economy which by nature was structurally unsustainable, but the only time I've seen where she talks about it's collapse is when the Europeans came.

Now, she does take pains to say that the efficiency and positive effects of the system have been exaggerated by posterity. On page 202 of the book which I linked to above she states "For many years Inca organization was admired by Europeans and praised as a kind of utopia. It was believed that the storage of goods of all kinds served humanitarian ends, such as rescuing the population in case of natural disaster. Such an interpretation demonstrates a lack of understanding of the economic mechanisms of the Inca state." The inverse was also true, she says, with many Indigenous peoples, exhausted by the demands of the Spanish, idealizing the Inca past as a native utopia.

TL;DR How well it fed it's people has been idealized by just about everyone, but basically, yeah, extreme hunger seems to have been unusual in the Inca Empire. That's as much as I'd be willing to venture before being out of my wheelhouse. Hope it helped.

Sources: Maria Rostworowski de Diez Canseco: History of the Inca Realm, Cambridge University Press, 1999 Vargas Llosa: Questions of Conquest, Harpers Magazine, 1990