Bangalore is nice, you will like it. It is pretty cosmopolitan and has a lot of the things you are probably used to here, plus it also has the traditional Indian things to do, see, eat and drink.
Just make sure you drink bottled water. If that is not possible make sure that the water is boiled before you drink it.
Avoid foods like (I shall give the Indian names here) Idly, Dosa, Masala Dosa, Poori, Roti, Chapati, Paraata, rice, khichdi, upma (pronounced oopma), breads cakes and pastries of course, which pretty much leaves you nothing much to eat
No, actually you can eat a lot of things: Curries for example. Just make sure that there is no sugar or jaggery (brown sugar) added in the cooking, and also that no cornstarch or flour is added while cooking. Sometimes the restaurants also add rice-flour to give it some body, make sure that is avoided. Normally restaurants will cook things the way you want it if you specify it explicitly.
Meats generally are cooked in two ways - tandoori style (basically barbecued in an earthen oven) or in curries. You are pretty much safe with the tandoori style meats, fish and birds, just make sure you take precautions with the curried types for the earlier mentioned reasons.
Avoid curds (yogurt), buttermilk and of course any sweets because 99% of Indian sweets are made with flour and/or dairy.
You can eat ghee (clarified butter), but it is not usually available by itself other than in stores.
Avoid anything that sounds like Pilaf or Pulav or Biriyani because they are all rice cooked in various spices including saffron. Very tasty and aromatic, but not Atkins approved
Avoid any dal of any kind. Avoid bajji, bonda, mysore bonda, vadai, pakoda beause they are all battered and fried dishes.
Veggies are usually boiled or fried or once again, curried. Be careful with the curried types.
By the way, for everyone here, Curry is not a dish in India. Curry means gravy. So you never just ask for Curry. You ask for Chicken curry or lamb curry or vegetable curry or egg curry etc. And curry can be cooked in infinitely different ways depending on what you put into it in terms of the liquid, veggies, spices etc. Every state/province in India makes curries in different tastes. Everyone who meets me for the first time or speaks with me on the phone and realises I am Indian always says "I love Curry, do you make/eat curry"? I have to explain all this to them
In the unheard towns you mention, it may be difficult to order in English, which is why I gave you some Indian names.
If there is anything else I can tell you, feel free to ask.
Hope this hhelps.
Cheers