title: Thyroid hormones and changes in body weight and metabolic parameters in response to weight loss diets: the POUNDS LOST trial.
abstract: The role of thyroid hormones in diet-induced weight loss and subsequent weight regain is largely unknown.
  
  
  
  To examine the associations between thyroid hormones and changes in body weight and resting metabolic rate (RMR) in a diet-induced weight loss setting.
  
  
  
  Data analysis was conducted among 569 overweight and obese participants aged 30-70 years with normal thyroid function participating in the 2-year Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST randomized clinical trial. Changes in body weight and RMR were assessed during the 2-year intervention. Thyroid hormones (free triiodothyronine (T3), free thyroxine (T4), total T3, total T4 and thyroid-stimulating hormone (TSH)), anthropometric measurements and biochemical parameters were assessed at baseline, 6 months and 24 months.
  
  
  
  Participants lost an average of 6.6 kg of body weight during the first 6 months and subsequently regained an average of 2.7 kg of body weight over the remaining period from 6 to 24 months. Baseline free T3 and total T3 were positively associated, whereas free T4 was inversely associated, with baseline body weight, body mass index and RMR. Total T4 and TSH were not associated with these parameters. Higher baseline free T3 and free T4 levels were significantly associated with a greater weight loss during the first 6 months (P<0.05) after multivariate adjustments including dietary intervention groups and baseline body weight. Comparing extreme tertiles, the multivariate-adjusted weight loss±s.e. was -3.87±0.9 vs -5.39±0.9 kg for free T3 (Ptrend=0.02) and -4.09±0.9 vs -5.88±0.9 kg for free T4 (Ptrend=0.004). The thyroid hormones did not predict weight regain in 6-24 months. A similar pattern of associations was also observed between baseline thyroid hormones and changes in RMR. In addition, changes in free T3 and total T3 levels were positively associated with changes in body weight, RMR, body fat mass, blood pressure, glucose, insulin, triglycerides and leptin at 6 months and 24 months (all P<0.05).
  
  
  
  In this diet-induced weight loss setting, higher baseline free T3 and free T4 predicted more weight loss, but not weight regain among overweight and obese adults with normal thyroid function. These findings reveal a novel role of thyroid hormones in body weight regulation and may help identify individuals more responsive to weight loss diets.
authors.affiliation: Department of Nutrition, Harvard TH Chan School of Public Health, Boston, MA, USA.|Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: G
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Epidemiology and Department of Biostatistics, Harvard TH Chan School of Public Health, Boston, MA, USA.
authors.forename: L
authors.initials: L
authors.lastname: Liang
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Bray
authors.affiliation: Department of Nutrition, Harvard TH Chan School of Public Health, Boston, MA, USA.|Department of Epidemiology, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA, USA.|Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: L
authors.initials: L
authors.lastname: Qi
authors.affiliation: Department of Nutrition, Harvard TH Chan School of Public Health, Boston, MA, USA.|Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: F B
authors.initials: FB
authors.lastname: Hu
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Rood
authors.affiliation: Department of Nutrition, Harvard TH Chan School of Public Health, Boston, MA, USA.|Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: F M
authors.initials: FM
authors.lastname: Sacks
authors.affiliation: Department of Nutrition, Harvard TH Chan School of Public Health, Boston, MA, USA.|Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Sun
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D000068959:Body Weight Maintenance; D031204:Caloric Restriction; D004038:Diet, Reducing; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000097:blood / Q000178:diet therapy* / Q000503:physiopathology; D013963:Thyroid Hormones / Q000097:blood*; D055105:Waist Circumference; D015431:Weight Loss / Q000502:physiology*
chemical_list: D020738:Leptin; D013963:Thyroid Hormones