Here's a list of a few places within 4kms of IISc. 

Sadashivnagar

Mast Kalandar (North Indian Vegetarian),

Mint Masala (North Indian),

Vegetarian), Pizza Hut, Chung Wah (Chinese)

Gold course Road

Le Brassiare at Le Meridian (Multi-cuisine), Dakshin at Windor

Manor (South Indian)

Infantry Road

South Indies (South Indian Vegetarian), Samarkand (Afgan)

Cunningham Road

Millers 46ers (Steak house), restaurants at the Sigma Mall, PizzaHut

Sanjaynagar

Hunan (Chinese), KFC, McDonalds

A little farther from IISc is the Church Street area, which has over 50 restaurants of all kinds. 
The website www.hungrybangalore.com has a listing of most restaurants in Bangalore and lets you order takeaways online.