Not getting enough sleep may prevent optimal weight loss results, according to findings published in the journal Annals of Internal Medicine.

Over the course of one month, a total of 10 people aged 35 to 49 who were considered obese followed a low-caloric diet. Researchers then had participants follow two different sleep regimens for two weeks – eight and a half hours and five and a half hours.

During the first part, individuals averaged 7 hours and 25 nights of sleep per night, while participants slept for an average of 5 hours and 14 minutes throughout the second phase. For their dietary regimen, each person consumed approximately 1,450 calories each day.

The results of the study showed that throughout the first phase, individuals lost more than 3 pounds of body fat. However, when their sleep was restricted, they only lost approximately 1 pound of body fat.

Plamen Penev, lead author of the research, stated that “cutting back on sleep, a behavior that is ubiquitous in modern society, appears to compromise efforts to lose fat through dieting.” He added that “one should not ignore the way they sleep when going on a diet.”

The Centers for Disease Control and Prevention report that from 2007 to 2008, an estimated one-third of all Americans were considered obese.