Seriously, take very little and buy what you need when you are there. If you are a 'big' person things will be a little more difficult to source as most Indians are smaller than us UK folks.
I would certainly echo that statement after going there last year. I'm 6'2", 34" waist, and have size 44 (UK 10) feet. Finding clothes which fitted me was difficult, as what little were in my size were short in the arm and "generous" in the torso. Shoes were almost impossible to find outside of the more expensive places in anything near my size. I finally found a cheap pair of boots £6 and a fleece £1.5 though - just don't forget to haggle (as the starting price was closer to £30).
I wouldn't recommend Jungle boots from personal experience - I had a pair with me for a trip to Borneo in the month after with some people from this forum. Because of the filter at the bottom, they allow the contents of every sludge ridden puddle to come into your boot. Not a good idea given the tendency for people to use streets as bathrooms, I think we can agree you don't want that coming into your boot. They are also overkill for the environment, as I found Indian "Jungle" not much different from a dry scrubland with a few more vines and trees.
For general use, I found a dusty pair of trainers was sufficient, with some boots for the more mountainous areas towards the north east. If you're staying in Kerala/Goa, then don't frett too much, as they have huge "tourist" markets which tend to sell the things which will fit you, albeit at an inflated (by Indian standards) price.
On the issue of food - most people I talked to were ill at least once. I found it safe to eat from street vendors, but insisted on seeing the item cooked in front of me (the ruse of "show me how you cook it, as I want to learn" was often used to ensure I didn't offend). Always go to the busiest vendor too, as they have a high turnover of food. I found it often safer to eat with my hands too, as the cutlery looked dirtier than I can describe. At least I know where my hands had been!
Enjoy your time there - you should have a good one!