Objective: To examine the associations between eating behavior traits and weight loss according to sleep quality and duration in adults enrolled in common weight-loss interventions.
Methods: Participants included overweight and obese men and women (n=150) (mean±s.d. age, 38.8±8.6 years; mean±s.d. body mass index (BMI), 33.3±3.5 kg m−2) who were subjected to a dietary intervention over a period of 12–16 weeks. Anthropometric measurements, eating behavior traits (Three-Factor Eating Questionnaire), sleep quality (total Pittsburgh Sleep Quality Index (PSQI) score) and sleep duration (hours per night, self-reported from the PSQI) were assessed at both baseline and post intervention. Linear regression analysis was used to quantify the relationships between eating behavior traits and changes in anthropometric markers for all subjects and by sleep categories (short sleep: <7 h per night vs recommended sleep: ≥7 h per night; poor sleep quality: ≥5 PSQI score vs good sleep quality: <5 PSQI score). We adjusted for age, sex and baseline BMI in analyses.
Results: Baseline eating behavior traits were modest predictors of weight-loss success, but they were all significantly associated with their changes over the weight-loss intervention (P<0.01). The diet intervention induced significant changes in eating behavior traits and even more for those having a non-favorable eating behavior profile at baseline. We observed that changes in flexible control and strategic dieting behavior were constantly negatively associated with changes in body weight and fat mass (P<0.05) for recommended duration sleepers. The change in situational susceptibility to disinhibition was positively associated with the change in fat mass and body weight for those having healthy sleeping habits (P<0.05). For poor quality sleepers, the change in avoidance of fattening foods was negatively associated with changes in adiposity (P<0.05).
Conclusion: Eating behavior traits and sleep may act together to influence the outcome of weight-loss programs.
Alex’s Notes: Both a lack of sleep and poor quality sleep has an association with weight gain and obesity, and evidence also suggests that these factors play a facilitating role in not just weight loss, but also the amount of fat loss when dieting. Moreover, we have previously seen how shorter sleep duration impacts both children and adults through an association with increased food intake. The current study sought to examine all these relationships in dieting adults and determine what relationships, if any, exist between eating behaviors, sleep quality/quantity, loss of body weight, fat mass, and waist circumference (WC).
To do so, the researchers pooled the data from four weight-reducing interventions that had been performed at their institution (Laval University, Quebec, Canada), the results of which have been previously published. All the studies used a standardized hypocaloric diet in addition to a weight-loss supplement or placebo. As the main outcomes in these studies were the differences in weight loss between the intervention (supplement) and control (placebo) groups, the researchers only used the weight loss data from the control groups so as to avoid any confounding effects of the intervention supplement.
Overall, 150 overweight and obese (average BMI of 33kg/m2) men and women aged 20-55 years (avg. 38-years) were included in the present analysis. They all received a personalized diet supervised by a registered dietitian that created a roughly 500-700 kcal daily deficit, and the study durations varied from 12-16 weeks. Moreover, none of the subjects exercised more than 20 minutes per week, consumed more than two alcoholic drinks per day, or consumed more than five cups of coffee per day.Every two weeks from the beginning until the end of the studies, participants met their assigned dietician where dietary compliance was verified by comparing the diet prescribed (total daily energy intake and macronutrient composition) to the actual diet composition of the participants (24 hour food recalls). At baseline and at the end of the study periods, all subjects underwent DXA or underwater weighing to determine body fat, completed the Pittsburgh Sleep Quality Index (PSQI) to determine subjective sleep quality, and a 3-day food record for two weekdays and one weekend day.
Get on with it!
Okay, okay. There are a lot of associations going on, so pardon me if I get rambling. On average, the subjects lost 3.7kg (8lbs) of weight, 2.8kg (6lbs; 75% of weight lost) of fat mass, and 5cm off their waist circumference. I want to point out, however, that the standard deviations were nearly the same as the averages, suggesting that weight and fat loss varied from zero to three times the average. Regardless, at the end of the interventions, sleep quality was significantly improved whereas sleep duration was not.
Eating behaviors and sleep
As determined by the PSQI, the subjects were divided into two groups for sleep quality (good/bad) and sleep quantity (short sleep <7 hours/night vs adequate sleep ≥7 hours/night). The amount of flexible control was significantly negatively associated with the loss of fat mass in good quality sleepers only. In other words, the greater the flexible control, the more fat one lost. Additionally, in the good quality sleepers, susceptibility to hunger and external locus of hunger were significantly association with the change in fat mass. Conversely, susceptibility to hunger was negatively associated with the change in body weight in poor quality sleepers.
The above associations were with regard to baseline characteristics. However, across all subjects, cognitive dietary restraint and its subcategories all significantly increased in response to the diet intervention, whereas disinhibition and its related sub-scores all significantly decreased. Thus, the researchers did another analysis looking at the relationship between the changes in eating behaviors and dieting success.
In all subjects, increases in dietary restraint, flexible control, strategic dieting behavior, and avoidance of fattening food were associated with greater fat loss, whereas increases in situational susceptibility was associated with less fat loss. When divided by sleep quality, the only relationships to remain significant were the avoidance of fattening foods in poor quality sleepers, and situational susceptibility in good quality sleepers. When divided by sleep duration, only attitude to self-regulation predicted fat loss in those getting less than seven hours per night, whereas in those getting seven or more hours had increased fat loss with increasing flexible control, strategic dieting behavior, and avoidance of fattening foods, and a decrease of situational susceptibility.
Putting it all together
Let’s assume you are an overweight or obese person, and that you are determined to lose weight. You aim to get more than seven hours of sleep per night and have good quality sleep through circadian support such as not blasting your eyes with a TV right up until bed, as well as vigorous physical activity earlier in the day. Of course life gets in the way, making some nights not ideal in terms of quality or duration. Regardless, before you even start dieting, having greater flexible control over your dietary habits will predict greater fat loss, while your susceptibility to hunger will impede it.
But you are determined to make the cognitive changes necessary for success. Accordingly, increasing your dietary restraint, flexible control, strategic dieting behavior, and avoidance of fattening foods will all predict greater fat loss. On the other hand, situational susceptibility will impede progress. So what does this mean? Say you go out to eat with friends. Increased dietary restraint and reduced situational susceptibility are exemplified by denying the breadsticks sitting on the table despite all your friends eating them. Strategic dieting behavior and avoidance of fattening food means ordering the steak with steamed vegetables instead of the double cheeseburger with fries. And flexible control means not freaking out when the vegetables come back sautéed instead of steamed, enjoying the treat, and getting on with your life because one tiny screw up isn’t going to impede fat loss more than the unnecessary stress that worrying about it would.
On a final note, I want to mention that all the significant associations above had a very minor correlation ranging between 0.2 and 0.3 (the closer to 1 the stronger the correlation), suggesting that they explain only a small part of the big picture. Moreover, other dimensions of sleep such as timing and consistency were not assessed and could easily also influence eating behaviors, and personality traits were not controlled for in the study, which appear to also be important fat-loss determinants. Nonetheless, sleep may modulate eating behaviors, and the two may work together to help predict weight loss in dieting adults.