Diet Walking

Can you loose 100 pounds in three months by low calorie diet and walking four miles a day?

Depends on what your starting weight is.
Significant weight loss by changing ones activities and diet are seen when your starting weight is considered overweight and have previously live a sedentary life style

Day 14: 222 lbs – 35 lbs Lost Liquid Diet! Impatient Dieter Perfect Walking Fat Burning Exercise