Lower Core Body Temperature and Greater Body Fat Are Components of a Human Thrifty Phenotype

Int J Obes (Lond). 2016 May;40(5):754-60. doi: 10.1038/ijo.2015.229. Epub 2015 Oct 26.

Abstract

Background/objectives: In small studies, a thrifty human phenotype, defined by a greater 24-hour energy expenditure (EE) decrease with fasting, is associated with less weight loss during caloric restriction. In rodents, models of diet-induced obesity often have a phenotype including a reduced EE and decreased core body temperature. We assessed whether a thrifty human phenotype associates with differences in core body temperature or body composition.

Subjects/methods: Data for this cross-sectional analysis were obtained from 77 individuals participating in one of two normal physiology studies while housed on our clinical research unit. Twenty-four-hour EE using a whole-room indirect calorimeter and 24-h core body temperature were measured during 24 h each of fasting and 200% overfeeding with a diet consisting of 50% carbohydrates, 20% protein and 30% fat. Body composition was measured by dual X-ray absorptiometry. To account for the effects of body size on EE, changes in EE were expressed as a percentage change from 24-hour EE (%EE) during energy balance.

Results: A greater %EE decrease with fasting correlated with a smaller %EE increase with overfeeding (r=0.27, P=0.02). The %EE decrease with fasting was associated with both fat mass and abdominal fat mass, even after accounting for covariates (β=-0.16 (95% CI: -0.26, -0.06) %EE per kg fat mass, P=0.003; β=-0.0004 (-0.0007, -0.00004) %EE kg(-1) abdominal fat mass, P=0.03). In men, a greater %EE decrease in response to fasting was associated with a lower 24- h core body temperature, even after adjusting for covariates (β=1.43 (0.72, 2.15) %EE per 0.1 °C, P=0.0003).

Conclusions: Thrifty individuals, as defined by a larger EE decrease with fasting, were more likely to have greater overall and abdominal adiposity as well as lower core body temperature consistent with a more efficient metabolism.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Intramural

MeSH terms

  • Absorptiometry, Photon
  • Adipose Tissue
  • Adiposity / physiology*
  • Adult
  • Arizona
  • Body Composition / physiology*
  • Body Temperature / physiology*
  • Caloric Restriction
  • Cross-Sectional Studies
  • Energy Metabolism / physiology*
  • Fasting / physiology
  • Female
  • Humans
  • Male
  • Phenotype*
  • Reproducibility of Results
  • Thermogenesis