title: No effect of caloric restriction on salivary cortisol levels in overweight men and women.
abstract: OBJECTIVE
  The effect of weight loss by diet or diet and exercise on salivary cortisol levels, a measure of hypothalamic pituitary adrenal activity, in overweight individuals is not known. The objective was to test the hypothesis that 24 weeks of moderate caloric restriction (CR) (25%) by diet or diet and aerobic exercise would alter morning and diurnal salivary cortisol levels.
  
  
  METHODS
  Randomized control trial in an institutional research center.
  
  
  METHODS
  Thirty-five overweight (BMI: 27.8±0.7 kg/m(2)) but otherwise healthy participants (16 M/19 F).
  
  
  METHODS
  Participants were randomized to either calorie restriction (CR: 25% reduction in energy intake, n=12), calorie restriction+exercise (CR+EX: 12.5% reduction in energy intake+12.5% increase in exercise energy expenditure, n=12) or control (healthy weight-maintenance diet, n=11) for 6 months.
  
  
  METHODS
  Salivary cortisol measured at 8:00, 8:30, 11:00, 11:30, 12:30, 13:00, 16:00 and 16:30. Morning cortisol was defined as the mean cortisol concentration at 08:00 and 08:30. Diurnal cortisol was calculated as the mean of the 8 cortisol measures across the day.
  
  
  RESULTS
  In the whole cohort, higher morning and diurnal cortisol levels were associated with impaired insulin sensitivity (morning: P=0.004, r(2)=0.24; diurnal: P=0.02, r(2)=0.15). Using mixed model analysis, there was no significant effect of group, time or sex on morning or diurnal cortisol levels.
  
  
  CONCLUSIONS
  A 10% weight loss with a 25% CR diet alone or with exercise did not impact morning or diurnal salivary cortisol levels.
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808; The Charles Perkins Centre and School of Biological Sciences, University of Sydney, NSW, Australia.
authors.forename: Charmaine S
authors.initials: CS
authors.lastname: Tam
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Frost
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808.
authors.forename: Wenting
authors.initials: W
authors.lastname: Xie
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rood
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808.
authors.forename: Eric
authors.initials: E
authors.lastname: Ravussin
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808. Electronic address: leanne.redman@pbrc.edu.
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Redman
mesh_terms: D000328:Adult; D031204:Caloric Restriction; D002940:Circadian Rhythm; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000188:drug therapy* / Q000378:metabolism*; D012463:Saliva / Q000378:metabolism*; D016896:Treatment Outcome; D015431:Weight Loss
chemical_list: D006854:Hydrocortisone
keywords: ACTH; AIRg; Acute insulin response to glucose; Adrenocorticotropic hormone; BMI; Body Mass Index; CALERIE; CR; CR+EX; Calorie restriction; Calorie restriction+exercise; Cortisol; EE; ELISA; Energy expenditure; Enzyme-linked immunosorbant assay; HPA; Hypothalamic pituitary adrenal; IGF; Insulin sensitivity; Insulin-like growth factor; LCD; Low calorie diet; Obesity; PBRC; Pennington Biomedical Research Center; Si; T3; T4; TSH; The Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy; Thyroid stimulating hormone; Thyroxine; Triiodothyronine; VLCD; Very low calorie diet.; Weight loss