Objectives: Some of the major challenges associated with successful dietary weight management include the identification of individuals not responsive to specific interventions. The aim was to investigate the potential relationship between weight loss and circadian rhythmicity, using wrist temperature and actimetry measurements, in women undergoing a weight-loss program, in order to assess whether circadian rhythmicity could be a marker of weight-loss effectiveness.
Methods: Participants were 85 overweight and obese women (body mass index, BMI: 30.24±4.95 kg m−2) subjected to a weight-reduction program. Efficacy of the treatment was defined as total weight loss, percentage of initial weight and weekly weight loss rates. Circadian rhythmicity in wrist temperature motor activity and position were analyzed using different sensors.
Results: Lower weight loss was related with a more flattened pattern measured as amplitude from cosinor (r=0.235, P=0.032), a higher fragmentation of rhythms determined by higher intradaily variability (IV) (r=−0.339, P=0.002), and an impaired wrist temperature circadian rhythm determined by the means of Circadian Function Index (r=0.228, P=0.038). Further analyses showed that low responders displayed lower amplitude (0.71±0.36 versus 1.24±0.62, P=0.036) and higher fragmentation of the circadian rhythm (0.24±0.11 versus 0.15±0.07, P=0.043) than high responders. Whereas we did not find significant differences in total activity rates between high responders and low responders, we found significant differences for the mean values of body position for high responders (39.12±3.79°) as compared with low responder women (35.31±2.53°, P=0.01).
Conclusions: Circadian rhythms at the beginning of the treatment are good predictors of future weight loss. Further treatment should consider chronobiological aspects to diagnose obesity and effectiveness of treatments.
Alex’s Notes: We learned last week that weight plateaus during dieting are explained by lack of dietary adherence. This isn’t to say that other factors are not involved however. There is a growing interest in circadian rhythms and some research suggests that obesity and metabolic syndrome are associated with chronodysruption. Indeed, the major components of energy homeostasis, including the sleep–wake cycle, thermogenesis, feeding, and glucose and lipid metabolism, are subjected to circadian regulation that synchronizes energy intake and expenditure with changes in the external environment. The main purpose of the study at hand was to quantify these effects by investigating the predictive ability of circadian rhythmicity on weight-loss effectiveness.
85 overweight and obese women (BMI 30; age 40 years) were recruited to undergo a weight-loss intervention followed by a weight-maintenance period. Additionally, they had their temperature and movement rhythms tracked for eight consecutive days using a temperature sensor and accelerometer, respectively.
“Participants attended weekly 60-min group therapy sessions during an average of 5 months. The duration of the program was variable and it depended on the individual weight-loss goal. After reaching their pre-established weight-loss goals, they were placed on a 5-month maintenance program.”
.Overall, the average weight loss during the first 21 weeks was 10% of initial body weight, or 8.5 kg (18.7 lbs), but there was huge inter-individual variance. Those who responded best to the Mediterranean diet lost 15-30% their initial body weight, while those who did not respond well actually gained about 1%. Moreover,
“When we represented the mean values of wrist temperature, actimetry and body position, according to the responsiveness status, across the 24-h period (Figure 2), we found statistically significant differences along the day in circadian rhythmicity patterns between high responders and low responders for wrist temperature and body position.”
Notably, overall physical activity was not different between the groups (high vs low responders). The results of this study show that successful dieters had a more robust circadian rhythm profile than unsuccessful dieters. Unfortunately, the dieting and circadian markers are only associated, meaning we cannot say that one caused the other. However, given previous studies looking at the effects of sleep disruption on food intake and metabolism, it seems likely that circadian rhythms play a huge role in weight-loss.
Bottom line: Rise with the sun, sleep with the moon, don’t eat after dark, and exercise early.