Whole body lipid oxidation during exercise is impaired with poor insulin sensitivity but not with obesity per se

Avigdor D. Arad, Fred J. DiMenna, Hannah D. Kittrell, Harry R. Kissileff, Jeanine B. Albu

Research output: Contribution to journalArticlepeer-review


Equivocal findings regarding the influence of overweight/obesity on exercise lipid-oxidizing capacity (EX-LIPOX) might reflect inadequate control of 1) acute energy balance/macronutrient composition of diet; 2) intensity/duration of exercise; and/or 3) insulin sensitivity (IS) of participant. To assess independent/combined influences of IS and overweight/obesity with other factors controlled, we recruited sedentary adults with normal weight (NW; n = 15) or overweight/obesity (O; n = 15) subdivided into metabolically healthy (MH; n = 8) and unhealthy (MU; n = 7) groups (IS; MH > MU). Participants completed a 9-day, weight-stabilizing, controlled-feeding protocol comprising measurements of resting metabolism, body composition, oral glucose tolerance, and maximal exercise capacity. We measured EX-LIPOX during the initial 45 min of "steady state"during constant-work-rate cycling at 70% and 100% of participant gas-exchange threshold (GET). At 70%, average EX-LIPOX in absolute (0.11 ± 0.02 g min-1) and relative (2.4 ± 0.3 mg kgFFM-1 min-1) terms was lower for NW-MU than MH regardless of body composition (NW-MH, 0.19 ± 0.02 g min-1/3.9 ± 0.3 mg kgFFM-1 min-1; O-MH, 0.19 ± 0.02 g min-1/ 3.7 ± 0.3 mg kgFFM-1 min-1), whereas no difference was present for NW-MU and O-MU (0.15 ± 0.02 g min-1/2.8 ± 0.3 mg kgFFM-1 min-1). Multiple regression confirmed that with IS-controlled, overweight/obesity was not associated with decreased EX-LIPOX, whereas decreased EX-LIPOX was associated with decreased IS independent of overweight/obesity. Overweight/obesity also did not influence EX-LIPOX across MH groups or with cohort divided by body-composition classification alone (P > 0.05). Exercise lipid-oxidizing capacity is impaired with poor IS regardless of body composition, but not with overweight/obesity per se.

Original languageEnglish
Pages (from-to)E366-E377
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number4
StatePublished - Oct 2022


  • exercise
  • insulin resistance
  • lipid oxidation
  • metabolic health
  • obesity


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