Purdue University
Overweight and obese adults who
are losing weight with a high-protein diet are more likely to sleep better,
according to new research from Purdue University.
"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 Wayne Campbell, a professor of nutrition science.
"We found that while consuming a lower calorie diet with a higher amount of protein, sleep quality improves for middle-age adults. This sleep quality is better compared to those who lost the same amount of weight while consuming a normal amount of protein."
These findings are published in the American Journal of Clinical Nutrition,
which is affiliated with the American Society for Nutrition. The research was
funded by Beef Checkoff, National Pork Board, National Dairy Council, Purdue
Ingestive Behavior Research Center and National Institutes of Health.
A pilot study found that in 14 participants, consuming
more dietary protein resulted in better sleep after four weeks of weight loss.
Then, in the main study, 44 overweight or obese participants were included to
consume either a normal-protein or a higher-protein weight loss diet.
After
three weeks of adapting to the diet, the groups consumed either 0.8 or 1.5
kilograms of protein for each kg of body weight daily for 16 weeks. The
participants completed a survey to rate the quality of their sleep every month
throughout the study.
Those who consumed more protein while losing weight
reported an improvement in sleep quality after three and four months of dietary
intervention.
A dietitian designed a diet that met each study
participant's daily energy need and 750 calories in fats and carbohydrates were
trimmed per day while maintaining the protein amount based on whether they were
in the higher- or normal-protein group.
The sources of protein used in the two
studies varied from beef, pork, soy, legumes and milk protein.
"Short sleep duration and compromised sleep quality
frequently lead to metabolic and cardiovascular diseases and premature
death," said Jing Zhou, a doctoral student in nutrition science and the
study's first author. "Given the high prevalence of sleep problems it's
important to know how changes to diet and lifestyle can help improve
sleep."
Campbell's lab also has studied how dietary protein
quantity, sources and patterns affect appetite, body weight and body
composition.
"This research adds sleep quality to the growing
list of positive outcomes of higher-protein intake while losing weight, and
those other outcomes include promoting body fat loss, retention of lean body
mass and improvements in blood pressure," Campbell said.
"Sleep is
recognized as a very important modifier of a person's health, and our research
is the first to address the question of how a sustained dietary pattern
influences sleep. We've showed an improvement in subjective sleep quality after
higher dietary protein intake during weight loss, which is intriguing and also
emphasizes the need for more research with objective measurements of sleep to
confirm our results."