A new study from Purdue University shows that Obese and overweight middle-aged adults trying slim down with high-protein diet are more likely to have better sleep.

Affiliated with the American Society for Nutrition and funded by National Dairy Council, National Institutes of Health, Beef Checkoff, National Pork Board and Purdue Ingestive Behavior Research Center, the results were published in the American Journal of Clinical Nutrition.

"Most research looks at the effects of sleep on diet and weight control, and our research flipped that question to ask what are the effects of weight loss and diet -- specifically the amount of protein - on sleep," said Dr. Wayne Campbell, a professor of nutrition science.

He added that the quality of sleep improves for those middle-aged adults consuming lower calorie intake and having high-protein diet as compared to those adults who lost the same weight but consumed a normal protein diet.

The initial study found that 14 subjects who consume high-protein diet resulted to have a better sleep in the four-week weight loss period. On the main study, where the researchers involved 44 overweight and obese participants, they provided normal-protein and high-protein weight loss diet in a 16 weeks' time.

The participants were asked to consume 0.8 or 1.5 kilogram (1.76 pounds or 3.3 pounds) of protein for every kilogram of body weight. Every month, the participants are asked to rate the quality of their sleep. Results show that those with high-protein weight loss diet reported an improved quality of sleep.

The high protein diet was composed of pork, beef, legumes, soy and milk protein.

"Given the high prevalence of sleep problems it's important to know how changes to diet and lifestyle can help improve sleep," said Jing Zhou, first author of the study and a doctoral student in nutrition science.

On Campbell's laboratory, they also studied the effects of protein quantity, sources and patterns to appetite, body composition and weight.

Campbell added that the study was first to address questions on how dietary pattern affects the quality of sleep.

Along with Campbell and Zhou are Jung Eun Kim, Cheryl Armstrong, and Ningning Chen, co-authors of the study.

Photo: Nate Steiner | Flickr