In India, as in many Muslim countries, it is very important to remember only to use your right hand when eating, handling money, and for giving and receiving things. Your left hand is only used for more personal purposes such as wiping your bottom and for handling items that have been in contact with the ground, so for example when you are taking off your shoes (important to remember when entering temples, some homes and shops).
The most likely origin for the right hand/left hand rule lies in the Arab nomadic world: in the desert, soap and water were not readily available and sand was the only cleaning material. It was a logical decision to reserve one hand for the most hygienic activities such as food preparation, and one for less clean purposes.
Although it is a simple and obvious rule, it seems to be very easy to forget. A fast-food chain launched a new advertising campaign in Asia some years ago, in which a person was shown holding a hamburger with both hands. It was not until a Muslim employee pointed out the problem that the company understood why their sales had fallen so dramatically.
Eating with only your right hand may take a bit of practice, but it is worth the trouble; Indians say it increases the taste of your food! Ask to be shown the tecniques. Once you got it, it is possible to eat very properly!