Association of circulating biomarkers with illness severity measures differentiates myalgic encephalomyelitis/chronic fatigue syndrome and post-COVID-19 condition: a prospective pilot cohort study.

BACKGROUND: Accumulating evidence suggests that autonomic dysfunction and persistent systemic inflammation are common clinical features in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID. However, there is limited knowledge regarding their potential association with circulating biomarkers and illness severity in these conditions. METHODS: This single-site, prospective, cross-sectional, pilot cohort study aimed to distinguish between the two patient populations by using self-reported outcome measures and circulating biomarkers of endothelial function and systemic inflammation status. Thirty-one individuals with ME/CFS, 23 individuals with long COVID, and 31 matched sedentary healthy controls were included. All study participants underwent non-invasive cardiovascular hemodynamic challenge testing (10 min NASA lean test) for assessment of orthostatic intolerance. Regression analysis was used to examine associations between outcome measures and circulating biomarkers in the study participants. Classification across groups was based on principal component and discriminant analyses. RESULTS: Four ME/CFS patients (13%), 1 with long COVID (4%), and 1 healthy control (3%) presented postural orthostatic tachycardia syndrome (POTS) using the 10-min NASA lean test. Compared with matched healthy controls, ME/CFS and long COVID subjects showed higher levels of ET-1 (p < 0.05) and VCAM-1 (p < 0.001), and lower levels of nitrites (NOx assessed as NO2- + NO3-) (p < 0.01). ME/CFS patients also showed higher levels of serpin E1 (PAI-1) and E-selectin than did both long COVID and matched control subjects (p < 0.01 in all cases). Long COVID patients had lower TSP-1 levels than did ME/CFS patients and matched sedentary healthy controls (p < 0.001). As for inflammation biomarkers, both long COVID and ME/CFS subjects had higher levels of TNF-α than did matched healthy controls (p < 0.01 in both comparisons). Compared with controls, ME/CFS patients had higher levels of IL-1ß (p < 0.001), IL-4 (p < 0.001), IL-6 (p < 0.01), IL-10 (p < 0.001), IP-10 (p < 0.05), and leptin (p < 0.001). Principal component analysis supported differentiation between groups based on self-reported outcome measures and biomarkers of endothelial function and inflammatory status in the study population. CONCLUSIONS: Our findings revealed that combining biomarkers of endothelial dysfunction and inflammation with outcome measures differentiate ME/CFS and Long COVID using robust discriminant analysis of principal components. Further research is needed to provide a more comprehensive characterization of these underlying pathomechanisms, which could be promising targets for therapeutic and preventive strategies in these conditions.

Skin Temperature Circadian Rhythms and Dysautonomia in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: The Role of Endothelin-1 in the Vascular Tone Dysregulation.

There is accumulating evidence of autonomic dysfunction in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS); however, little is known about its association with circadian rhythms and endothelial dysfunction. This study aimed to explore the autonomic responses through an orthostatic test and analysis of the peripheral skin temperature variations and vascular endothelium state in ME/CFS patients. Sixty-seven adult female ME/CFS patients and 48 healthy controls were enrolled. Demographic and clinical characteristics were assessed using validated self-reported outcome measures. Postural changes in blood pressure, heart rate, and wrist temperature were recorded during the orthostatic test. Actigraphy during one week was used to determine the 24-h profile of peripheral temperature and activity. Circulating endothelial biomarkers were measured as indicators of endothelial functioning. Results showed that ME/CFS patients presented higher blood pressure and heart rate values than healthy controls in the supine and standing position (p < 0.05 for both), and also a higher amplitude of the activity rhythm (p < 0.01). Circulating levels of endothelin-1 (ET-1) and vascular cell adhesion molecule-1 (VCAM-1) were significantly higher in ME/CFS (p < 0.05). In ME/CFS, ET-1 levels were associated with the stability of the temperature rhythm (p < 0.01), and also with the self-reported questionnaires (p < 0.001). This suggests that ME/CFS patients exhibited modifications in circadian rhythm and hemodynamic measures, which are associated with endothelial biomarkers (ET-1 and VCAM-1). Future investigation in this area is needed to assess dysautonomia and vascular tone abnormalities, which may provide potential therapeutic targets for ME/CFS.

Coupling Between Subregional Oscillators Within the Suprachiasmatic Nucleus Determines Free-Running Period in the Rat.

Rats housed in a 22-h light-dark cycle (11:11, T22) exhibit 2 distinct circadian locomotor activity (LMA) bouts simultaneously: one is entrained to the LD cycle and a second dissociated bout maintains a period greater than 24 h. These 2 activity bouts are associated with independent clock gene oscillations in the ventrolateral (vl-) and dorsomedial (dm-) suprachiasmatic nucleus (SCN), respectively. Previous results in our laboratory have shown that the vl- and dm-SCN oscillators are weakly coupled under T22 and that the period of the dissociated bout depends on coupling between the 2 subdivisions. Here, we sought to study the behavior of the T22 SCN pacemaker upon release into free-running conditions and compare it to the behavior of the system upon release from typical 24-h (12:12, T24) entrainment. T22-desynchronized rats or T24-entrained rats were released into constant darkness (DD). Activity rhythms in T22 rats rapidly resynchronized upon release into DD, and the free-running period (FRP) of the fused rhythm was longer than the FRP of T24 rats. We then asked whether the in vivo period changes were also present in the ex vivo SCN. Per1-luc rats were desynchronized in T22 for assessment of SCN Per1-luc ex vivo. Similar to behavioral FRP, the period of ex vivo SCN explanted from T22 rats was longer than that for T24 animals. Mathematical models supported the observed behavior of the dual oscillator system as the result of mutual coupling between the vl- and dm-SCN oscillators. This bidirectionally coupled model predicted both the FRP of the T22 system and its phase-shifting response to light. Together, these data support a model of pacemaker organization in which a light-sensitive vl-SCN oscillator is mutually coupled with a light-insensitive dm-SCN oscillator, and together they determine the period of the coupled system as a whole and its response to light pulses.

Emotional eating and cognitive restraint mediate the association between sleep quality and BMI in young adults.

This cross-sectional study was designed to investigate whether diet quality and eating behaviors could mediate the association between sleep quality and body mass index (BMI) in young adults. For all participants (n = 925; aged 21.4 ± 2.5 years; 77.8% women) we evaluated: BMI, sleep quality, diet quality, and eating behavior dimensions (emotional eating, cognitive restraint, and uncontrolled eating). Linear regression models were used to test associations between exposure and outcome variables. Path analysis was conducted with all potential mediators and covariates entered at the same time. Results showed that emotional eating (ß = 0.04 [95% CI: 0.03; 0.06]), cognitive restraint (ß = 0.03 [95% CI: 0.01; 0.04]), uncontrolled eating (ß = 0.02 [95% CI: 0.01; 0.04]) and diet quality (ß = -0.14 [95% CI: 0.19;-0.08]) were significantly associated with sleep quality. Additionally, BMI was significantly associated with PSQI score (ß = 0.09 [95% CI: 0.01; 0.17]), emotional eating (ß = 0.89 [95% CI: 0.60; 1.18]), and cognitive restraint (ß = 1.37 [95% CI: 1.02; 1.71]). After testing for mediation, results revealed that emotional eating and cognitive restraint evidenced a significant mediating effect on the association between sleep quality and BMI. Additionally, diet quality was significantly associated with emotional eating (ß = -0.35 [95% CI: 0.56;-0.13]), cognitive restraint (ß = 0.53 [95% CI: 0.27; 0.79]), and uncontrolled eating (ß = -0.49 [95% CI: 0.74;-0.25]). In conclusion, young adults with poor sleep quality are more likely to deal with negative emotions with food, which, in turn, could be associated with higher cognitive restraint, becoming a vicious cycle that has a negative impact on body weight. Our results also emphasize the role of eating behaviors as determinants of diet quality, highlighting the importance of considering sleep quality and eating behaviors when designing obesity prevention strategies in this population.

Time-Restricted Feeding during Puberty Ameliorates Adiposity and Prevents Hepatic Steatosis in a Mouse Model of Childhood Obesity.

BACKGROUND: Time restricted feeding (TRF) refers to dietary interventions in which food access is limited during a specific timeframe of the day. TRFs have proven useful in improving metabolic health in adult subjects with obesity. Their beneficial effects are mediated, in part, through modulating the circadian rhythm. Nevertheless, the translation of these dietary interventions onto obese/overweight children and adolescents remains uncharacterized. The objective of this study is to explore the feasibility of temporal dietary interventions for improving metabolic health in the context of childhood obesity. METHODS: We have previously developed a mouse model of early adiposity (i.e., childhood obesity) through litter size reduction. Mice raised in small litters (SL) became obese as early as by two weeks of age, and as adults, they developed several obesity-related co-morbidities, including insulin resistance, glucose intolerance and hepatic steatosis. Here, we explored whether two independent short-term chrono-nutritional interventions might improve metabolic health in 1-month-old pre-pubertal SL mice. Both TRFs comprised 8 h feeding/14 h fasting. In the first one (TRF1) Control and SL mice had access to the diet for 8 h during the dark phase. In the second intervention (TRF2) food was available during the light:dark transitions. RESULTS: TRF1 did not alter food intake nor ameliorate adiposity in SL-TRF1. In contrast, SL-TRF2 mice showed unintentional reduction of caloric intake, which was accompanied by reduced total body weight and adiposity. Strikingly, hepatic triglyceride content was completely normalized in SL-TRF1 and SL-TRF2 mice, when compared to the ad lib-fed SL mice. These effects were partially mediated by (i) clock-dependent signals, which might modulate the expression of Pparg or Cpt1a, and (ii) clock-independent signals, such as fasting itself, which could influence Fasn expression. CONCLUSIONS: Time-restricted feeding is an effective and feasible nutritional intervention to improve metabolic health, namely hepatic steatosis, in a model of childhood obesity. These data open new avenues for future safe and efficient chrono-nutritional interventions aimed to improve metabolic health in children with overweight/obesity.

Late bedtime is associated with lower weight loss in patients with severe obesity after sleeve gastrectomy.

BACKGROUND: Previous research has shown that sleep can play a role in obesity and weight loss. However, the association of sleep with weight loss in patients with severe obesity after bariatric surgery remains unexplored. We aimed to evaluate the role of sleep in weight loss evolution in a cohort of patients who underwent sleeve gastrectomy. METHODS: A cohort of 252 patients with severe obesity (75.7% women; age [mean ± SD] 47.7 ± 10.8 years; BMI 44.2 ± 5.9 kg/m2) was followed for 1 year after surgery. Anthropometric, biochemical, physical activity, sleep (bedtime, wakeup time, and sleep duration) and dietary intake variables were collected pre- and post-surgery (1 year). Linear and non-linear regression models were used to examine the associations between sleep variables and weight loss. Participants were grouped into 'early' and 'late' sleepers according to a bedtime threshold (before or after 24:00 h), and the differences in weight loss, physical activity, meal timing, and dietary intake between groups were studied. RESULTS: 1-h increments in bedtime were linearly associated with less excess weight loss (EWL) [-2.23%; 95%CI: -3.37; -0.70; p = 0.005] 1 year after the sleeve gastrectomy. Late sleepers lost less weight (-5.64% of EWL [95%CI: -10.11; -1.17]; p = 0.014) when compared to early sleepers and showed a higher energy intake after 21:00 h (8.66% of total energy intake [95% CI: 4.87; 12.46]; p < 0.001). CONCLUSIONS: Late bedtime is associated with less success of weight loss 1 year after the sleeve gastrectomy. Late sleepers consumed more of their calories closer to bedtime. Our results highlight the relevance of considering recommendations on bedtime and meal timing for patients after bariatric surgery.

Sleeve gastrectomy in patients with severe obesity restores circadian rhythms and their relationship with sleep pattern.

Advances in research have linked alterations of circadian rhythms with obesity. However, few studies have focused on the recovery of the circadian expression after a weight loss treatment. Our aim was to study the alterations of the circadian rhythmicity due to morbid obesity and the recovery of the circadian pattern after weight loss in a cohort of patients who underwent sleeve gastrectomy. For this purpose, 41 patients with severe obesity (75% women; age [mean (SD)] 49.7 ± 10 years; BMI 44.3 ± 6.2 kg/m2) were monitored before bariatric surgery and 9 months afterward. On both occasions, activity and wrist temperature were determined by actigraphy and were related with weight loss. Anthropometric, biochemical, and sleep-related variables, along with dietary intake and physical activity, were analyzed in relation with circadian rhythmicity. Results show significant differences in the circadian expression before and after 9 months of bariatric surgery, with more stable and less fragmented rhythms after weight loss. Moreover, only after surgery were the circadian variables associated to sleep timing and chronotype. The findings of this study indicate that weight loss treatment in patients with morbid obesity improves the circadian rhythm expression, and in such a way that it could be associated with better sleep quality. Moreover, it allows the recovery of the relationship between sleep patterns and circadian rhythm that was lost due to the obesity.

Circadian Patterns of Patients with Type 2 Diabetes and Obstructive Sleep Apnea.

Sleep apnea, a condition that modifies sleep and circadian rhythms, is highly prevalent in patients with diabetes. However, it is not known if there is an association between sleep apnea, circadian alterations and glycemic regulation in this type of patient. Here, a polysomnographic study was carried out on 21 women and 25 men (mean age = 64.3 ± 1.46 years) with diagnoses of type 2 diabetes to detect the presence of sleep apnea. Moreover, patients wore an actigraph and a temperature sensor on the wrist for one week, to study the manifestation of the circadian rhythms. The correlations of circadian and polysomnographic variables with the severity of apnea, measured by the apnea-hypopnea index, and with glycemic dysregulation, measured by the percentage of glycated hemoglobin, were analyzed. The mean apnea-hypoapnea index of all the participants was 39.6 ± 4.3. Apnea-hypoapnea index correlated with % N1, negatively with % N3, and also the stability of the active circadian rhythm. However, no significant correlation was found between the apnea-hypopnea index and wrist temperature rhythm and glycated hemoglobin. Glycated hemoglobin levels were negatively associated with the percentage of variance explained by the wrist temperature circadian rhythm (calculated via 24 and 12 h rhythms). This association was independent of body mass index and was strongest in patients with severe apnea. In conclusion, patients with diabetes showed altered circadian rhythms associated with a poor glycemic control and this association could partially be related to the coexistence of sleep apnea.

Neonatal overfeeding during lactation rapidly and permanently misaligns the hepatic circadian rhythm and programmes adult NAFLD.

Childhood obesity is a strong risk factor for adult obesity, type 2 diabetes, and cardiovascular disease. The mechanisms that link early adiposity with late-onset chronic diseases are poorly characterised. We developed a mouse model of early adiposity through litter size reduction. Mice reared in small litters (SLs) developed obesity, insulin resistance, and hepatic steatosis during adulthood. The liver played a major role in the development of the disease. OBJECTIVE: To gain insight into the molecular mechanisms that link early development and childhood obesity with adult hepatic steatosis and insulin resistance. METHODS: We analysed the hepatic transcriptome (Affymetrix) of control and SL mice to uncover potential pathways involved in the long-term programming of disease in our model. RESULTS: The circadian rhythm was the most significantly deregulated Gene Ontology term in the liver of adult SL mice. Several core clock genes, such as period 1-3 and cryptochrome 1-2, were altered in two-week-old SL mice and remained altered throughout their life course until they reached 4-6 months of age. Defective circadian rhythm was restricted to the periphery since the expression of clock genes in the hypothalamus, the central pacemaker, was normal. The period-cryptochrome genes were primarily entrained by dietary signals. Hence, restricting food availability during the light cycle only uncoupled the central rhythm from the peripheral and completely normalised hepatic triglyceride content in adult SL mice. This effect was accompanied by better re-alignment of the hepatic period genes, suggesting that they might have played a causal role in mediating hepatic steatosis in the adult SL mice. Functional downregulation of Per2 in hepatocytes in vitro confirmed that the period genes regulated lipid-related genes in part through peroxisome proliferator-activated receptor alpha (Ppara). CONCLUSIONS: The hepatic circadian rhythm matures during early development, from birth to postnatal day 30. Hence, nutritional challenges during early life may misalign the hepatic circadian rhythm and secondarily lead to metabolic derangements. Specific time-restricted feeding interventions improve metabolic health in the context of childhood obesity by partially re-aligning the peripheral circadian rhythm.

Higher eating frequency is associated with lower adiposity and robust circadian rhythms: a cross-sectional study.

BACKGROUND: Although overweight and obesity are assumed to arise from an energy imbalance, evidence has shown that the frequency and timing of meals are also potential risk factors for obesity. However, the lack of a consistent approach to define eating patterns relative to internal circadian rhythms limits the extent of these findings. OBJECTIVES: The objective of this study was to investigate the association of the circadian pattern of energy intake with adiposity and with internal circadian rhythms. METHODS: A total of 260 Spanish adults (aged 20-30 y; 78.1% women) were included in a 6-d cross-sectional study. Participants documented sleep and dietary intake within the study period. From these data, we evaluated the chronotype, eating patterns (meal timing, eating duration, and eating frequency), and we obtained the daily profile of energy intake. In addition, we evaluated the circadian pattern of wrist temperature (internal circadian rhythm marker). Circadian patterns of energy intake and wrist temperature were analyzed, and their association among them and with anthropometric variables and diet quality was studied. RESULTS: The greater fragmentation of the circadian pattern of energy intake was associated with lower BMI (in kg/m2; -10.55; 95% CI: -16.96, -4.13; P = 0.001). In addition, a greater eating frequency (≥5 eating occasions/d) was significantly associated with lower BMI (-1.88; 95% CI: -3.27, -0.48) and higher energy intake after 20:00 (4.14% of kcal; 95% CI: 1.67, 7.16). Furthermore, a greater eating frequency was associated with lower fragmentation (P = 0.042) and greater stability of the circadian pattern of wrist temperature (P = 0.016). CONCLUSIONS: The daily pattern of energy intake is associated with adiposity and robust circadian rhythms. Our results shed light on the relevance of eating frequency as a potential zeitgeber for the circadian system. Although more evidence is needed, eating frequency could be considered for future chrono-nutritional recommendations for the prevention of circadian misalignment and obesity.

ADHD subtypes are associated differently with circadian rhythms of motor activity, sleep disturbances, and body mass index in children and adolescents: a case-control study.

To date, few studies have examined the circadian pattern of motor activity in children and adolescents newly diagnosed with attention-deficit/hyperactivity disorder (ADHD). The objective was to study the circadian pattern of motor activity in subjects with ADHD (medication naïve) and to investigate the relationships between alterations in circadian patterns, the ADHD subtype (combined or inattentive), sleep disturbances and body mass index (BMI). One-hundred twenty children and adolescents (60 medication naïve ADHD and 60 controls) were included in a gender- and age-matched case-control study. ADHD was diagnosed according to the DSM-IV-TR, the Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version, and the Conner's Parents Rating Scale-Revised. Circadian rhythms of motor activity and sleep parameters were measured using actigraphy and the Sleep Disturbance Scale for Children. BMI and dietary intake were also evaluated. ADHD patients showed a trend towards eveningness and greater sleep disturbances than controls. Additionally, patients with ADHD-combined had significantly higher mean values of motor activity and showed a significant delay in bedtime. Furthermore, among ADHD-C patients hyperactivity symptoms were significantly associated with the least 5 h of activity. Regarding patients with ADHD-inattentive, increased fragmentation of the circadian pattern was associated with inattention symptoms, and they also showed a significant increase in BMI of 2.52 kg/m2 [95% CI 0.31, 4.73] in comparison with controls. Our findings highlight the potential use of actigraphy as a clinical tool to aid in the diagnosis of ADHD. It should be noted that evaluating motor activity variables could also allow the differentiation between ADHD subtypes.

Attenuating Effect of Peruvian Cocoa Populations on the Acute Asthmatic Response in Brown Norway Rats.

Cocoa contains bioactive components, which vary according to genetic and environmental factors. The present study aimed to ascertain the anti-allergic properties of native Peruvian cocoa populations ("Blanco de Piura" or BPC, "Amazonas Peru" or APC, "Criollo de Montaña" or CMC, "Chuncho" or CCC, and an ordinary cocoa or OC). To do so, after an initial in vitro approach, an in vivo study focused on the induction of an anaphylactic response associated with allergic asthma in Brown Norway rats was carried out. Based on their polyphenol content, antioxidant activity and in vitro effects, the APC and CMC were selected to be included in the in vivo study. Cocoa diets were tested in a model of allergic asthma in which anaphylactic response was assessed by changes in body temperature, motor activity and body weight. The concentration of specific immunoglobulin E (IgE), mast cell protease and leukotrienes was also quantified in serum and/or bronchoalveolar lavage fluid. CMC and OC populations exhibited a protective effect on the allergic asthma rat model as evidenced by means of a partial protection against anaphylactic response and, above all, in the synthesis of IgE and the release of mast cell protease.

Adiposity and body mass index of young women are associated with altered 24-hour profile of wrist temperature and sleep quality.

Sleep alterations are linked to circadian disturbances; however, these variables are also related with adiposity, which could impair the study of the previous relationship. Here, we investigated whether the association between adiposity and impaired circadian health is independent of sleep and circadian related variables in a sample of young women. One hundred ninety-two women (18-30 years of age) participated in this cross-sectional study. To evaluate circadian rhythmicity, subjects wore a temperature sensor for six consecutive days, and variables related with the amplitude and stability of the rhythm were calculated. We also assessed adiposity markers (body mass index [BMI], fat mass, waist, and hip circumference), sleep and circadian variables (sleep schedules and quality, social jet lag, and chronotype), energy intake, and physical activity. Partial correlations were conducted to test the associations between circadian and sleep-related variables with adiposity markers. Results showed the circadian pattern of temperature clearly depended on BMI and, to a lesser extent, on sleep variables. Specifically, we showed that higher adiposity was significantly associated with lower amplitude, percentage of variance explained by the rhythm, and intradaily variability and L10 values of the temperature 24 h rhythm. Furthermore, sleep quality was the only variable significantly related with both adiposity and circadian pattern of wrist temperature, while social jet lag and chronotype were only associated with the circadian pattern of temperature. Therefore, we consider BMI should be taken into account when sleep health or disturbances are studied by means of circadian rhythm analyses.

Development and Characterization of an Allergic Asthma Rat Model for Interventional Studies.

Allergic asthma is one of the most common chronic diseases of the airways, however it still remains underdiagnosed and hence undertreated. Therefore, an allergic asthma rat model would be useful to be applied in future therapeutic strategy studies. The aim of the present study was to develop an objective model of allergic asthma in atopic rats that allows the induction and quantification of anaphylactic shock with quantitative variables. Female Brown Norway rats were intraperitoneally sensitized with ovalbumin (OVA), alum and Bordetella pertussis toxin and boosted a week later with OVA in alum. At day 28, all rats received an intranasal challenge with OVA. Anaphylactic response was accurately assessed by changes in motor activity and body temperature. Leukotriene concentration was determined in the bronchoalveolar lavage fluid (BALF), and total and IgE anti-OVA antibodies were quantified in blood and BALF samples. The asthmatic animals' motility and body temperature were reduced after the shock for at least 20 h. The asthmatic animals developed anti-OVA IgE antibodies both in BALF and in serum. These results show an effective and relatively rapid model of allergic asthma in female Brown Norway rats that allows the quantification of the anaphylactic response.

Erratum: Eating Jet Lag: A Marker of the Variability in Meal Timing and its Association with Body Mass Index.

The Nutrients Editorial Office would like to update the error in the original published version[1] [...].

The Elapsed Time between Dinner and the Midpoint of Sleep is Associated with Adiposity in Young Women.

Meal timing relative to sleep/wake schedules is relevant in the search for obesity risk factors. However, clock time does not accurately characterize the timing of food intake in the context of internal circadian timing. Therefore, we studied elapsed between dinner and the midpoint of sleep (TDM) as a practical approach to evaluate meal timing relative to internal timing, and its implications on obesity. To do so, adiposity, sleep, diet, physical activity, and TDM were measured in 133 women. The participants were grouped into four categories according to their sleep timing behavior (early-bed/early-rise; early-bed/late-rise; late-bed/early-rise; late-bed/late-rise). Differences among the categories were tested using ANOVA, while restricted cubic splines were calculated to study the association between TDM and adiposity. Our results show that, although participants had dinner at about the same time, those that had the shortest TDM (early-bed/early-rise group) were found to have significantly higher BMI and waist circumference values (2.3 kg/m2 and 5.2 cm) than the other groups. In addition, a TDM of 6 h was associated with the lowest values of adiposity. The TDM could be a practical approach to personalizing meal timing based on individual sleep/wake schedules. Thus, according to our findings, dining 6 h before the midpoint of sleep is an important finding and could be vital for future nutritional recommendations and for obesity prevention and treatment.

Eating Jet Lag: A Marker of the Variability in Meal Timing and Its Association with Body Mass Index.

The timing of food intake has been associated with obesity and adverse metabolic outcomes, independently of the amount or content of food intake and activity level. However, the impact of the variability in the timing of food intake between weekends and weekdays on BMI (body mass index) remains unexplored. To address that, we propose to study a marker of the variability of meal timing on weekends versus weekdays (denominated as 'eating jet lag') that could be associated with increments in BMI. This cross-sectional study included 1106 subjects (aged 18-25 years). Linear regression models were used to examine the associations of eating jet lag with BMI and circadian related variables (including chronotype, eating duration, sleep duration, and social jet lag). Subsequently, a hierarchical multivariate regression analysis was conducted to determine whether the association of eating jet lag with BMI was independent of potentially confounding variables (e.g., chronotype and social jet lag). Moreover, restricted cubic splines were calculated to study the shape of the association between eating jet lag and BMI. Our results revealed a positive association between eating jet lag and BMI (p = 0.008), which was independent of the chronotype and social jet lag. Further analysis revealed the threshold of eating jet lag was of 3.5 h or more, from which the BMI could significantly increase. These results provided evidence of the suitability of the eating jet lag, as a marker of the variability in meal timing between weekends and weekdays, for the study of the influence of meal timing on obesity. In a long run, the reduction of the variability between meal timing on weekends versus weekdays could be included as part of food timing guidelines for the prevention of obesity among general population.

Social Jet Lag Associates Negatively with the Adherence to the Mediterranean Diet and Body Mass Index among Young Adults.

Obesity and unhealthy eating habits have been associated with irregular sleep-wake patterns during the week, also known as social jet lag. The Mediterranean diet is a healthy pattern related with a better health and sleep quality. However, potential associations with social jet lag remain unexplored. The aim of this study was to examine whether higher social jet lag is linked to lower adherence to the Mediterranean diet and whether it is associated with BMI (Body Mass Index). This cross-sectional study included 534 young adults (18-25 years). Anthropometric parameters, adherence to the Mediterranean diet, chronotype and social jet lag were studied. Our results revealed that individuals with greater social jet lag showed lower adherence to the Mediterranean diet and had a higher BMI. Among the habits that characterized the Mediterranean dietary pattern, we observed that higher social jet lag was significantly associated with a lower intake of fruits and vegetables, as well as skipping breakfast. Hence, the promotion of regular sleep habits together with healthy dietary patterns should be considered for obesity prevention, especially among young adults.

Seasonal variation of body weight loss after bariatric surgery.

Seasonal variations have been described in humans in several variables such as sleep, mood, appetite, food preferences, or body weight. We hypothesized that these variations could also influence the decrease in body weight rate in patients submitted to body weight loss interventions. Thus, here we tested the variations of weight loss according to the time of the year the surgery took place in a group patients (n = 1322) submitted to bariatric surgery in the Hospital Universitari de la Vall d'Hebron in Barcelona (geographical coordinates: 41°25'41″N 2°8'32″E). For the analysis, the percentage of total body weight loss (%TWL), excess body weight loss (%EWL) and percentage of body mass index loss (%BMIL) were calculated at 3 (n = 1255), 6 (n = 1172), 9 (n = 1002), and 12 months (n = 1076) after surgery. For %EWL and %BMIL a statistically significant seasonal variation was detected when the variables were calculated at 3 months, but not at the other times, with more weight loss in summer-fall. However, seasonal variations were not detected for %TWL (p = 0.09). The mean amplitude of the seasonal rhythm for %EWL was of 1.8%, while for the rhythm of %BMIL was 0.7%. Moreover, a second peak was detected in January-February modulating the seasonal rhythm of the two variables. Results confirm seasonal variations in humans and indicate that short term responses to weight loss can be modulated by the time of year.