European Journal of Applied Physiology

, Volume 111, Issue 12, pp 3135–3141

Carbohydrate intake reduces fat oxidation during exercise in obese boys

  • Lisa Chu
  • Michael C. Riddell
  • Tim Takken
  • Brian W. Timmons
Original Article


The recent surge in childhood obesity has renewed interest in studying exercise as a therapeutic means of metabolizing fat. However, carbohydrate (CHO) intake attenuates whole body fat oxidation during exercise in healthy children and may suppress fat metabolism in obese youth. To determine the impact of CHO intake on substrate utilization during submaximal exercise in obese boys, seven obese boys (mean age: 11.4 ± 1.0 year; % body fat: 35.8 ± 3.9%) performed 60 min of exercise at an intensity that approximated maximal fat oxidation. A CHO drink (CARB) or a placebo drink (CONT) was consumed in a double-blinded, counterbalanced manner. Rates of total fat, total CHO, and exogenous CHO (CHOexo) oxidation were calculated for the last 20 min of exercise. During CONT, fat oxidation rate was 3.9 ± 2.4 mg × kg fat-free mass (FFM)−1 × min−1, representing 43.1 ± 22.9% of total energy expenditure (EE). During CARB, fat oxidation was lowered (p = 0.02) to 1.7 ± 0.6 mg × kg FFM−1 × min−1, contributing to 19.8 ± 4.9% EE. Total CHO oxidation rate was 17.2 ± 3.1 mg × kg FFM−1 × min−1 and 13.2 ± 6.1 mg × kg FFM−1 × min−1 during CARB and CONT, respectively (p = 0.06). In CARB, CHOexo oxidation contributed to 23.3 ± 4.2% of total EE. CHO intake markedly suppresses fat oxidation during exercise in obese boys.


Metabolism Childhood obesity Energy expenditure Exercise 


  1. Brandou F, Savy-Pacaux AM, Marie J, Brun JF, Mercier J (2006) Comparison of the type of substrate oxidation during exercise between pre and post pubertal markedly obese boys. Int J Sports Med 27:407–414PubMedCrossRefGoogle Scholar
  2. Dougherty KA, Chow M, Kenney WL (2009) Responses of lean and obese boys to repeated summer exercise in the heat bouts. Med Sci Sports Exerc 41:279–289PubMedGoogle Scholar
  3. Lazzer S, Busti C, Agosti F, De CA, Pozzo R, Sartorio A (2007) Optimizing fat oxidation through exercise in severely obese Caucasian adolescents. Clin Endocrinol (Oxf) 67:582–588Google Scholar
  4. Maffeis C, Zaffanello M, Pellegrino M, Banzato C, Bogoni G, Viviani E, Ferrari M, Tato L (2005) Nutrient oxidation during moderately intense exercise in obese prepubertal boys. J Clin Endocrinol Metab 90:231–236PubMedCrossRefGoogle Scholar
  5. Mirwald RL, Baxter-Jones AD, Bailey DA, Beunen GP (2002) An assessment of maturity from anthropometric measurements. Med Sci Sports Exerc 34:689–694PubMedCrossRefGoogle Scholar
  6. Pallikarakis N, Sphiris N, Lefebvre P (1991) Influence of the bicarbonate pool and on the occurrence of 13CO2 in exhaled air. Eur J Appl Physiol Occup Physiol 63:179–183PubMedCrossRefGoogle Scholar
  7. Riddell MC, Bar-Or O, Hollidge-Horvat M, Schwarcz HP, Heigenhauser GJ (2000a) Glucose ingestion and substrate utilization during exercise in boys with IDDM. J Appl Physiol 88:1239–1246PubMedGoogle Scholar
  8. Riddell MC, Bar-Or O, Schwarcz HP, Heigenhauser GJ (2000b) Substrate utilization in boys during exercise with [13C]-glucose ingestion. Eur J Appl Physiol 83:441–448PubMedCrossRefGoogle Scholar
  9. Riddell MC, Bar-Or O, Wilk B, Parolin ML, Heigenhauser GJ (2001) Substrate utilization during exercise with glucose and glucose plus fructose ingestion in boys ages 10–14 yr. J Appl Physiol 90:903–911PubMedGoogle Scholar
  10. Riddell MC, Jamnik VK, Iscoe KE, Timmons BW, Gledhill N (2008) Fat oxidation rate and the exercise intensity that elicits maximal fat oxidation decreases with pubertal status in young male subjects. J Appl Physiol 105:742–748PubMedCrossRefGoogle Scholar
  11. Sinha R, Fisch G, Teague B, Tamborlane WV, Banyas B, Allen K, Savoye M, Rieger V, Taksali S, Barbetta G, Sherwin RS, Caprio S (2002) Prevalence of impaired glucose tolerance among children and adolescents with marked obesity. N Engl J Med 346:802–810PubMedCrossRefGoogle Scholar
  12. Tanner JM (1962) Growth at adolescence. Blackwell Scientific, Oxford, pp 32–37Google Scholar
  13. Timmons BW, Bar-Or O (2003) RPE during prolonged cycling with and without carbohydrate ingestion in boys and men. Med Sci Sports Exerc 35:1901–1907PubMedCrossRefGoogle Scholar
  14. Timmons BW, Bar-Or O, Riddell MC (2003) Oxidation rate of exogenous carbohydrate during exercise is higher in boys than in men. J Appl Physiol 94:278–284PubMedGoogle Scholar
  15. Timmons BW, Bar-Or O, Riddell MC (2007a) Energy substrate utilization during prolonged exercise with and without carbohydrate intake in preadolescent and adolescent girls. J Appl Physiol 103:995–1000PubMedCrossRefGoogle Scholar
  16. Timmons BW, Bar-Or O, Riddell MC (2007b) Influence of age and pubertal status on substrate utilization during exercise with and without carbohydrate intake in healthy boys. Appl Physiol Nutr Metab 32:416–425PubMedCrossRefGoogle Scholar
  17. Zunquin G, Theunynck D, Sesboue B, Arhan P, Bougle D (2006) Effects of puberty on glucose–lipid balance during exercise in the obese child. Appl Physiol Nutr Metab 31:442–448PubMedCrossRefGoogle Scholar
  18. Zunquin G, Theunynck D, Sesboue B, Arhan P, Bougle D (2009a). Comparison of fat oxidation during exercise between lean and obese pubertal boys: clinical implications. Br J Sports Med 43:869–870Google Scholar
  19. Zunquin G, Theunynck D, Sesboue B, Arhan P, Bougle D (2009b) Evolution of fat oxidation during exercise in obese pubertal boys: clinical implications. J Sports Sci 27:315–318PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Lisa Chu
    • 1
  • Michael C. Riddell
    • 2
  • Tim Takken
    • 1
  • Brian W. Timmons
    • 1
  1. 1.Children’s Exercise and Nutrition Centre, McMaster University, Children’s Hospital, Chedoke HospitalHamiltonCanada
  2. 2.School of Kinesiology and Health Science, Faculty of HealthYork UniversityTorontoCanada

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