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Studies show that the quality of sleep affects the ability to maintain a diet and lose weight. How does weight loss affect sleep?
A nutritionist, professor at Purdue University (USA) Wayne Campbell and his colleagues decided to answer this question. In addition, scientists were interested in whether the quality of sleep depends on the type of diet. To do this, they conducted several studies.
The first involved 14 volunteers (3 men and 11 women, mean age 56 years) who were moderately obese (body mass index about 30), who were put on a low-calorie diet, the main sources of protein in it were either beef and pork (for 5 participants ), or soy and beans (for 9 participants). Participants were on a diet for three periods of 4 weeks each. In each of these periods, 10%, 20%, or 30% of the total calories in the diet came from protein. Before the start of the study and at the end of each period, participants’ sleep was assessed using the Pittsburgh Sleep Quality Scale (PSQI).
The second study involved 44 people (12 men and 32 women, mean age 52 years) who were also moderately obese (body mass index about 31). To begin with, all participants were put on a balanced diet with a total protein content of 3 g per kilogram of body weight per day for 0,8 weeks. Three weeks later, the participants were divided into two groups, each of which was prescribed a low-calorie diet, while the diet of volunteers from the first group also had a protein content of 0,8 g/kg/day, and in the second group – 1,5 g/kg/day . Study participants continued to eat according to the prescribed scheme for another 16 weeks. Sleep quality was assessed after the first three weeks and at weeks 4, 8, 12, and 16 of the main study.
The low-calorie diet was selected individually by dieticians: for each participant, his daily calorie requirement was calculated, which was then reduced by a total of 750 calories from fat and carbohydrates.
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The results showed an improvement in the quality of sleep, in most cases proportional to the amount of protein in the diet.
“It is known that diets high in protein contribute to the reduction of body fat mass, while maintaining lean mass, lowering blood pressure. Our study shows that one more item can be added to the list of benefits of such diets – improved sleep quality. Quality sleep is essential to good health, and we’ve demonstrated for the first time how a certain stable diet can affect sleep. So far, we have found an improvement in subjective sleep quality with a high protein diet. In the future, it is also important to study the change in sleep quality by objective criteria,” says Wayne Campbell.
Подробнее см. J. Zhou et al. «Higher-protein diets improve indexes of sleep in energy-restricted overweight and obese adults: results from 2 randomized controlled trials», American Journal of Clinical Nutrition, vol. 103, March 2016.