Not saying it's the right way but i did a 1200-1500cal/day diet , pretty much a decent breakfast, then salad w/ chicken breast and water all day, along with walking appx 1-2 miles/day( went out and walked the complex at work at break, lunch and after work) and lost appx 50lbs in about 2 months, went from appx 230 to 180. I never felt tired or fatigued, but i also don't live an extremely active life style. I worked my way into it over a 2-3 week period dropping my caloric intake every couple of days. There are general guidelines, but listen to your body and you'll know what you need.