High circulating thyrotropin levels in obese women are reduced after body weight loss induced by caloric restriction

J Clin Endocrinol Metab. 2005 Aug;90(8):4659-63. doi: 10.1210/jc.2005-0920. Epub 2005 May 24.


Context: Previous clinical studies concerning the impact of body weight loss on single plasma TSH concentration measurements or the TSH response to TRH in obese humans have shown variable results.

Objective: The objective of this study was to investigate the effect of weight loss induced by caloric restriction on diurnal TSH concentrations and secretion in obese humans.

Design: This was a clinical, prospective, crossover study.

Setting: The study was conducted at the Clinical Research Center of Leiden University Medical Center.

Participants: Eleven obese premenopausal women (body mass index, 33.3 +/- 0.7 kg/m2) were studied.

Intervention: The study intervention was weight loss (50% reduction overweight by caloric restriction).

Main outcome measure(s): Twenty-four-hour plasma TSH concentrations (10-min intervals) and the 24-h TSH secretion rate, calculated by a waveform-independent deconvolution technique (Pulse), were determined.

Results: The 24-h TSH secretion rate was significantly higher in obese women than in normal weight controls, and weight loss was accompanied by diminished TSH release (before weight loss, 43.4 +/- 6.4 mU/liter.24 h; after weight loss, 34.4 +/- 5.9 mU/liter.24 h; P = 0.02). Circulating free T3 levels decreased after weight loss from 4.3 +/- 0.19 to 3.8 +/- 0.14 pmol/liter (P = 0.04). Differences in 24-h TSH release correlated positively with the decline of circulating leptin (r2 = 0.62; P < 0.01).

Conclusions: Elevated TSH secretion in obese women is significantly reduced by diet-induced weight loss. Among various physiological cues, leptin may be involved in this phenomenon. The decreases in TSH and free T3 may blunt energy expenditure in response to long-term calorie restriction, thereby frustrating weight loss attempts of obese individuals.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial

MeSH terms

  • Adult
  • Caloric Restriction*
  • Circadian Rhythm
  • Cross-Over Studies
  • Diet, Reducing*
  • Female
  • Humans
  • Leptin / blood
  • Obesity / blood*
  • Obesity / diet therapy*
  • Prospective Studies
  • Thyrotropin / blood*
  • Weight Loss


  • Leptin
  • Thyrotropin