At 5'9", Joe weighs 130 pounds. He may not look like a person who needs to count calories, but as part of his life extension program, he monitors every morsel of food that passes through his system.

Every day for the past seven years, Joe has limited himself to about 1,950 calories.

He believes that by eating less and restricting his caloric intake, he will trigger a genetic switch that slows the aging process.

Joe doesn't deprive himself of food. Instead, this 51-year-old father fills up on natural fruits, vegetables and lean proteins that are packed with essential vitamins and nutrients. "Whenever you're thinking about calorie restriction, you should continually think about getting the most nutritional bang per calorie," Joe says.