A 25 percent calorie restriction over two years by adults who were not obese was linked to better health-related quality of life (HrQoL), according to the results of a randomised clinical trial, published online by JAMA Internal Medicine. The researchers, led by Dr Corby K Martin of the Pennington Biomedical Research Center, Baton Rouge, LA, reported that calorie restriction had some positive effects and no negative effects on health-related QoL, and correlation analyses supported the association between weight loss and improved health-related QoL.
The report in their paper, ‘Effect of Calorie Restriction on Mood, Quality of Life, Sleep, and Sexual Function in Healthy Nonobese Adults: The CALERIE 2 Randomized Clinical Trial’, that they tested the effects of calorie restriction on aspects of quality of life that have been speculated to be negatively affected by calorie restriction, including decreased libido, lower stamina, depressed mood and irritability. Their work extends the literature with a study group of non-obese individuals because beneficial effects of calorie restriction on health span (length of time free of disease) increase the possibility that more people will practice calorie restriction.
In this clinical trial, conducted at three academic research institutions, 220 men and women with BMI22-28 were enrolled and divided almost two to one into two groups: the larger group was assigned to two years of 25 percent calorie restriction (CR group) and the other was an ad libitum (their own preference) control group (AL group) for comparison. The analysis included 218 participants and self-report questionnaires were used to measure mood, quality of life, sleep and sexual function.
Data were collected at baseline, a year and two years, and the study was concducted from January 2007 to March 2012.
In all, 218 participants (152 women) he CR, they report that both the CR and AL groups lost a mean (SE) of 7.6 (0.3) kg and 0.4 (0.5) kg, respectively, at month 24 (p<0.001). Compared with the AL group, the CR group had significantly improved mood, reduced tension and improved general health, and sexual drive and relationship at month 24, as well as improved sleep duration at month 12 (all p<0.05). Greater percent weight loss in the CR group at month 24 was associated with increased vigor (Spearman correlation coefficient, ρ= -0.30) and less mood disturbance (ρ=0.27) measured with the POMS, improved general health (ρ=-0.27) measured with the SF-36, and better sleep quality per the PSQI total score (ρ=0.28) (all p<0.01).
Overall, the calorie restriction group, compared with the control group, had improved mood, reduced tension and improved general health and sexual drive and relationship at year two, as well as improved sleep at year one. The bigger weight loss by the calorie restriction participants was associated with increased vigour, less mood disturbance, improved general health and better quality of sleep.
“The results from this study are helpful to health care professionals because they provide data on the effect of CR on health-related QoL overall and sex hormones in men in a sample that included normal-weight individuals,” the authors concluded. “Calorie restriction among primarily overweight and obese persons has been found to improve QoL, sleep and sexual function, and the results of the present study indicate that two years of CR is unlikely to negatively affect these factors in healthy adults; rather, CR is likely to provide some improvement.”
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