MNT: Weight Management (2015)
Citation:Chaput J, Tremblay A. Sleeping habits predict the magnitude of fat loss in adults exposed to moderate caloric restriction. Obesity Facts, 2012; 5: 561-566. PubMed ID: 22854682
Retrospective Cohort Study
B - Click here for explanation of classification scheme.
- To verify whether sleeping habits affect the magnitude of fat loss in overweight and obese adults subjected to moderate caloric restriction
- Hypothesis: Both sleep quantity and quality at baseline predict the success of a weight-reducing program in adults.
- Overweight and obese
- Men and women
- Aged between 25 years and 50 years
- Absence of menopause for women (cessation of menstruation)
- Stable body weight (body weight change of less than three kg for two months before intervention)
- Fewer than three periods of 20 minutes of physical activity per week
- No use of medication that could affect body weight
- No smoking
- Normal BP values (less than 140/90)
- Consumption of no more than 10 alcoholic beverages per week
- Consumption of no more than five cups of coffee per day.
- Normal weight
- Unstable body weight
- Three or more periods of 20 minutes of physical activity per week
- Use of medication that could affect body weight
- High BP values
- Consumption of more than 10 alcoholic beverages per week
- Consumption of more than five cups of coffee per day.
Description of Study Protocol:
Recruitment methods were not reported.
- For this study, three previously-published weight loss studies have been pooled together. Only individuals involved in the control groups of these studies were used for statistical analysis in the present study.
- Participants were subjected to moderate caloric restriction for 15 to 24 weeks, depending on the study
- Data was collected at baseline and at the end of the study.
- Participants were subjected to a 600kcal to 700kcal-per-day decrease in energy intake for 15 to 24 weeks, depending on the study
- Each participant met with the assigned dietitian every two weeks until the completion of the study.
- Multiple linear regression analysis was used, adjusting for age, sex, baseline BMI, length of intervention and change in energy intake as covariates.
- A two-tailed P-value of less than 0.05 was considered statistically significant.
Data Collection Summary:
Timing of MeasurementsBaseline and at the end of the weight loss program (between 15 weeks and 24 weeks, depending on each of the three programs).
- Sleep quality and sleep duration, measured by the Pittsburgh Sleep Quality Index (PSQI) and assessed only at baseline
- Body fat mass, measured by dual-energy X-ray absorptiometry
- Waist cirumference, measured at the line between the lower border of the last rib and the upper border of the ileac crest
- Dietary intake, measured by a three-day food record (two weekdays and one weekend day) and estimated by a dietitian using a computerized version of the Canadian Nutrient File.
Independent VariablesEnergy restriction (600kcal- to 700kcal-per-day decrease in energy intake supervised by a dietitian) diet and time (zero week baseline to 15 to 24 weeks post-test).
Control VariablesAge, sex, BMI, length of intervention and can change in daily energy intake (kJ per day) was used as a covariates.
Description of Actual Data Sample:
- Initial N: 123 (70 male, 53 female)
- Attrition (final N): 123
- Age: 41.1±6.0 years
- Ethnicity: Not described
- Other relevant demographics: Not described.
- Body weight: 94.7±14.5kg
- BMI: 33.2±3.6kg/m2
- Waist circumference: 106.4±10.1cm
- Fat mass: 35.7±8.3kg
- Fat mass: 38.1±7.1%
- Sleep duration: 7.1±1.0 hours
- PSQI (total score): 4.8±2.9
- Energy intake: 5,242±2,031kJ per day.
Summary of Results:
- Mean weight loss of all participants over the dietary intervention was 4.5±3.9kg, 76% of which came from fat stores
- A significant positive relationship between sleep duration and loss of body fat was observed, both in absolute (adjusted beta, 0.72kg per hour; P<0.05) and relative terms (adjusted beta, 0.77% per hour; P<0.01), after adjusting for covariates
- Sleep quality was inversely related to both fat mass loss (adjusted beta, -0.19; P<0.05) and percentage body fat loss (adjusted beta, -0.21; P<0.01) after adjusting for covariates, suggesting that a better sleep quality was associated with greater fat mass loss.
- Both sleep quantity and quality at baseline can predict the magnitude of fat loss in adults exposed to moderate caloric restriction
- Adequate sleep might influence the success of a weight loss intervention and perhaps sleep should be included as part of the lifestyle package that traditionally has focused on diet and exercise.
|Government:||Canadian Institutes of Health Research|
- Small sample size
- Questionnaire-based measurements (sleep duration and diet assessment)
- Residual confounding (other factors, such as personality traits, education factors or other lifestyle qualities, may affect sleeping habits and adherence to dietary intervention)
- Study is well suited for the identification of associations and does not permit causal inferences.
Quality Criteria Checklist: Primary Research
|1.||Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)||Yes|
|2.||Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?||Yes|
|3.||Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?||Yes|
|4.||Is the intervention or procedure feasible? (NA for some epidemiological studies)||Yes|
|1.||Was the research question clearly stated?||Yes|
|1.1.||Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?||Yes|
|1.2.||Was (were) the outcome(s) [dependent variable(s)] clearly indicated?||Yes|
|1.3.||Were the target population and setting specified?||Yes|
|2.||Was the selection of study subjects/patients free from bias?||Yes|
|2.1.||Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?||Yes|
|2.2.||Were criteria applied equally to all study groups?||N/A|
|2.3.||Were health, demographics, and other characteristics of subjects described?||Yes|
|2.4.||Were the subjects/patients a representative sample of the relevant population?||Yes|
|3.||Were study groups comparable?||Yes|
|3.1.||Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)||N/A|
|3.2.||Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?||N/A|
|3.3.||Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)||N/A|
|3.4.||If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?||Yes|
|3.5.||If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)||N/A|
|3.6.||If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?||N/A|
|4.||Was method of handling withdrawals described?||N/A|
|4.1.||Were follow-up methods described and the same for all groups?||N/A|
|4.2.||Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)||N/A|
|4.3.||Were all enrolled subjects/patients (in the original sample) accounted for?||N/A|
|4.4.||Were reasons for withdrawals similar across groups?||N/A|
|4.5.||If diagnostic test, was decision to perform reference test not dependent on results of test under study?||N/A|
|5.||Was blinding used to prevent introduction of bias?||Yes|
|5.1.||In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?||N/A|
|5.2.||Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)||Yes|
|5.3.||In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?||Yes|
|5.4.||In case control study, was case definition explicit and case ascertainment not influenced by exposure status?||N/A|
|5.5.||In diagnostic study, were test results blinded to patient history and other test results?||N/A|
|6.||Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?||???|
|6.1.||In RCT or other intervention trial, were protocols described for all regimens studied?||N/A|
|6.2.||In observational study, were interventions, study settings, and clinicians/provider described?||No|
|6.3.||Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?||Yes|
|6.4.||Was the amount of exposure and, if relevant, subject/patient compliance measured?||Yes|
|6.5.||Were co-interventions (e.g., ancillary treatments, other therapies) described?||???|
|6.6.||Were extra or unplanned treatments described?||???|
|6.7.||Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?||N/A|
|6.8.||In diagnostic study, were details of test administration and replication sufficient?||N/A|
|7.||Were outcomes clearly defined and the measurements valid and reliable?||Yes|
|7.1.||Were primary and secondary endpoints described and relevant to the question?||Yes|
|7.2.||Were nutrition measures appropriate to question and outcomes of concern?||Yes|
|7.3.||Was the period of follow-up long enough for important outcome(s) to occur?||Yes|
|7.4.||Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?||Yes|
|7.5.||Was the measurement of effect at an appropriate level of precision?||Yes|
|7.6.||Were other factors accounted for (measured) that could affect outcomes?||Yes|
|7.7.||Were the measurements conducted consistently across groups?||Yes|
|8.||Was the statistical analysis appropriate for the study design and type of outcome indicators?||Yes|
|8.1.||Were statistical analyses adequately described and the results reported appropriately?||Yes|
|8.2.||Were correct statistical tests used and assumptions of test not violated?||Yes|
|8.3.||Were statistics reported with levels of significance and/or confidence intervals?||Yes|
|8.4.||Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?||N/A|
|8.5.||Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?||Yes|
|8.6.||Was clinical significance as well as statistical significance reported?||Yes|
|8.7.||If negative findings, was a power calculation reported to address type 2 error?||N/A|
|9.||Are conclusions supported by results with biases and limitations taken into consideration?||Yes|
|9.1.||Is there a discussion of findings?||Yes|
|9.2.||Are biases and study limitations identified and discussed?||Yes|
|10.||Is bias due to study's funding or sponsorship unlikely?||Yes|
|10.1.||Were sources of funding and investigators' affiliations described?||Yes|
|10.2.||Was the study free from apparent conflict of interest?||Yes|