A Mechanical Engineer Joined a Work Weight-Loss Contest and Lost 50 Pounds Fasting Two Days a Week

Dave Wentworth, a mechanical engineer in Michigan, took up the 5:2 diet after a workplace weight-loss competition in 2011 — eating normally five days a week and fasting, with only dinner, on two non-consecutive days such as Tuesday and Thursday.

"In simple terms, it's eating as normally as you can for five days of the week and then on two days... you don't eat," he said, describing it as "a simple way to get basically a 20 percent reduction in total calories overall." On non-fasting days he ate a protein shake for breakfast, chicken stir fry for lunch, and a standard dinner of meat and vegetables; fasting-day meals leaned on vegetables, fiber-rich whole grains, and other low-calorie, high-volume foods.

Over six months, Wentworth lost 50 pounds. He has said he "feels great" with "a ton of energy," and maintains the loss by tracking his weight weekly and returning to fasting whenever it ticks up.