QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Online Supporting Material Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sonko, B. J. Articles by Hill, J. O. Search for Related Content PubMed PubMed Citation Articles by Sonko, B. J. Articles by Hill, J. O.

---

Human Nutrition and Metabolism

Ingested Fat Oxidation Contributes 8% of 24-h Total Energy Expenditure in Moderately Obese Subjects^1,2

University of Colorado Health Sciences Center, Denver, CO 80262 and ^* University of Kansas, Lawrence, KS 66045-2348

³To whom correspondence should be addressed. E-mail: bakary.sonko{at}uchsc.edu.

The role of ingested fat in the etiology of obesity is controversial. The aims of this study were to determine the contributions of ingested fat oxidation to: 1) 24-h total energy expenditure (TEE), and 2) substrate oxidation during acute stationary cycle exercises in adult humans. Healthy, moderately obese (n = 18; BMI = 31 ± 1 kg/m²) subjects (8 men; 10 women) were each studied in a whole-room calorimeter for 24 h. They were fed mixed meals (55, 30, and 15% as energy from carbohydrate, fat and protein, respectively) to maintain energy balance. Each subject performed 1255-kJ cycle exercises at 50% VO_2max in the calorimeter. Study test meal fat was labeled with carbon-13 (¹³C). Ingested fat oxidation was estimated from breath ¹³CO₂ excretion and the subject’s chamber CO₂ production. Total fat and carbohydrate oxidations were estimated from nonprotein respiratory quotient (NP-RQ) values. Endogenous fat oxidation was estimated as the difference between total fat and ingested fat oxidations. TEE was estimated from gas exchanges; 28 ± 3% of ingested fat was oxidized and it provided 8 ± 1% of 24-h TEE. During cycle exercises, ingested fat provided 50% of total fat oxidized and 13.0 ± 2% of energy expended. Endogenous fat oxidation contributed 10.4 ± 3% of energy expenditure during cycle exercises. This study extended to 24-h observations of previous studies that lasted 6–9 h on ingested fat oxidation in humans. Understanding the factors that promote ingested fat oxidation could lead to more effective obesity intervention programs.

KEY WORDS: • fat • oxidation • mixed-meals • obesity

This article has been cited by other articles:

				K. R Westerterp, A. Smeets, M. P Lejeune, M. P. Wouters-Adriaens, and M. S Westerterp-Plantenga Dietary fat oxidation as a function of body fat Am. J. Clinical Nutrition, January 1, 2008; 87(1): 132 - 135. [Abstract] [Full Text] [PDF]