Short Communication

International Journal of Obesity (2014) 38, 1248–1250; doi:10.1038/ijo.2014.7; published online 18 February 2014

Breath carbon stable isotope ratios identify changes in energy balance and substrate utilization in humans

L D Whigham1, D E Butz2, L K Johnson3, D A Schoeller4, D H Abbott5, W P Porter6 and M E Cook2

  1. 1USDA ARS Human Nutrition Research Center, Grand Forks, ND, USA and University of Wisconsin-Madison, Madison, WI, USA at time of work; Paso del Norte Institute for Healthy Living, El Paso, TX, USA at time of publication
  2. 2Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI, USA
  3. 3University of North Dakota, Grand Forks, ND, USA
  4. 4Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
  5. 5Department of Ob/Gyn and Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI, USA
  6. 6Department of Zoology, University of Wisconsin-Madison, Madison, WI, USA

Correspondence: Dr L Whigham, Paso del Norte Institute for Healthy Living, 500 W. University Ave, El Paso, TX 79968, USA. E-mail: ldwhigham@utep.edu

Received 28 January 2013; Revised 24 June 2013; Accepted 21 July 2013
Accepted article preview online 20 January 2014; Advance online publication 18 February 2014

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Abstract

Rapid detection of shifts in substrate utilization and energy balance would provide a compelling biofeedback tool for individuals attempting weight loss. As a proof of concept, we tested whether the natural abundance of exhaled carbon stable isotope ratios (breath δ13C) reflects shifts between negative and positive energy balance. Volunteers (n=5) consumed a 40% energy-restricted diet for 6 days followed by 50% excess on day 7. Breath was sampled immediately before and 1h and 2h after breakfast, lunch and dinner. Exhaled breath δ13C values were measured by cavity ring-down spectroscopy. Using repeated measures analysis of variance (ANOVA) followed by Dunnett’s contrasts, pre-breakfast breath values on days 2–6 were compared with day 1, and postprandial day 7 time points were compared with pre-breakfast day 7. Energy restriction diminished pre-breakfast breath δ13C by day 3 (P<0.05). On day 7, increased energy intake was first detected immediately before dinner (−23.8±0.6 vs −21.9±0.7‰, P=0.002 (means±s.d.)), and breath δ13C remained elevated at least 2h post dinner. In conclusion, when shifting between negative and positive energy balance, breath δ13C showed anticipated isotopic changes. Although additional research is needed to determine specificity and repeatability, this method may provide a biomarker for marked increases in caloric intake.

Keywords:

caloric restriction; cavity ring-down spectroscopy; stable isotope; weight loss

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