title: Evening chronotype associates with obesity in severely obese subjects: interaction with CLOCK 3111T/C.
abstract: Chronotype has been related to obesity and metabolic disturbances. However, little is known about the relationship between circadian preferences and genetic background in CLOCK genes with obesity and weight loss among severely obese patients after bariatric surgery.
  
  
  
  The research goals were (1) to examine whether evening chronotype is related to obesity and weight loss evolution in severely obese followed during 6 years after bariatric surgery and (2) to examine potential interactions between circadian preferences and CLOCK 3111T/C for obesity in this population.
  
  
  
  Participants (n=252, 79% female; age (mean±s.d.): 52±11 years; body mass index (BMI): 46.4±6.0 kg m-2) were grouped into evening and morning types. Obesity and weight loss parameters, energy and macronutrients intake, energy expenditure, chronotype, meal timing, sleep duration and CLOCK genotype were studied.
  
  
  
  Evening-type subjects showed significantly higher initial body weight (P=0.015) and BMI (P=0.014) than morning types. Moreover, evening-type, when compared with morning types, lost less weight (percentage of excess weight loss) after bariatric surgery (P=0.015). Weight-loss progression between the two chronotype groups differed significantly from the fourth year after the bariatric surgery toward a higher weight regain among evening types (P<0.05). We also detected a significant interaction between CLOCK 3111T/C SNP and chronotype for body weight at baseline (P<0.001). Specifically, among carriers of the risk allele C, evening types showed higher body weight than morning types (P=0.012). In addition, CLOCK 3111T/C SNP significantly associated with obesity and sleep duration in the older subjects.
  
  
  
  Evening chronotype is associated with higher obesity in severely obese subjects and with lower weight loss effectiveness after bariatric surgery. In addition, circadian preferences interact with CLOCK 3111T/C for obesity. The circadian and genetic assessment could provide tailored weight loss recommendations in subjects who underwent bariatric surgery.
authors.affiliation: Department Food Science and Nutrition, University of Barcelona, Barcelona, Spain.
authors.forename: T
authors.initials: T
authors.lastname: Ruiz-Lozano
authors.affiliation: Obesity Unit, Endocrinology and Nutrition Department, Hospital Clinic Universitari, Barcelona, Spain.|Institut d'Investigaciones Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.|Centro de Investigación Biomédica en Red de Diabtetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Vidal
authors.affiliation: Obesity Unit, Endocrinology and Nutrition Department, Hospital Clinic Universitari, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: de Hollanda
authors.affiliation: Department of Biostatistics, University of Murcia, Murcia, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Canteras
authors.affiliation: Department of Physiology, Faculty of Biology, University of Murcia, Murcia. Spain.|MIB-Arrixaca, Murcia. Spain.
authors.forename: M
authors.initials: M
authors.lastname: Garaulet
authors.affiliation: Department Food Science and Nutrition, University of Barcelona, Barcelona, Spain.|Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Izquierdo-Pulido
mesh_terms: D000328:Adult; D050110:Bariatric Surgery; D056926:CLOCK Proteins / Q000378:metabolism*; D002940:Circadian Rhythm / Q000235:genetics; D004734:Energy Metabolism / Q000502:physiology; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D005787:Gene Frequency; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000235:genetics / Q000378:metabolism* / Q000601:surgery; D011446:Prospective Studies; D013030:Spain / Q000453:epidemiology; D015431:Weight Loss / Q000235:genetics
chemical_list: D056926:CLOCK Proteins; C538943:CLOCK protein, human