Time restricted feeding diet: Watch the clock instead of calories

If you want to be lean in 2018, instead of counting calories, you might consider when you're eating.

It's a diet strategy called time restricted feeding. The idea? Eat normally - as much as you want - but only during a specific time frame. Doctors say the key is to sit down to meals within a 12-hour window in order to lose weight.

Dr. Julie Shatzel said she's also seen great health improvements, including better sleep and heightened energy, among her patients using the TRF method.

"I have seen my patients go off blood pressure medications and normalize their blood pressure completely," Dr. Shatzel said.

Holly Hisel, 42, has been trying time restricted feeding for the past three months.

"I get up at 6:30, I have breakfast at 8 o'clock. I'll have a snack during the day before lunch, then either I'm going out to happy hour or dinner between 5 and 7 and I'm pretty much done before 7 p.m.," Hisel said.

In a small study over 12 weeks, a group of obese participants were restricted to eating for just 8 hours a day. On average, they lost 5 percent of their body weight.

"Time-restricted feeding involves activating metabolic pathways that are silent in our bodies. If you shorten the time frame of eating you will still activate those pathways within your body that will increase fat burning and increase the utilization of stored energy," Dr. Shatzel said.

But eating within that 12-hour time frame means you're fasting the other 12 hours of a day - easier said than done.

"I had hunger pangs maybe a little bit for those first two weeks," Hisel said. "I adjusted it little by little and it was a lot easier than anticipated. I didn't really have to change my diet at all."

Some health experts say that for maximum weight loss, try limiting your eating window to 10 hours a day instead of 12.