[naivous]

for a start, the sugar cane grows naturally in tropical climates, so unless you live in the tropics it's not a food meant for you.
Also the cane itself is a different matter than the bleached crystals we consume in the west.
Our body is built to break down polysaccharides and dysaccharides (the natural sugars found in fruit and cereals) into glucose. The moment you ingest refined monosaccharides (sugar) you bypass a lot of its functions which will eventually atrophy if the body thinks they're not needed anymore.
because the body is a dynamic system the moment any of its natural functions stop we become ill.

You might like to read Sugar Blues by William Dufty, an excellent read, including a brief history of the sugar trade which is quite an eye-opener.