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A low‐glycemic diet lifestyle intervention improves fat utilization during exercise in older obese humans
Author(s) -
Solomon Thomas P. J.,
Haus Jacob M.,
Cook Marc A.,
Flask Chris A.,
Kirwan John P.
Publication year - 2013
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1002/oby.20411
Subject(s) - medicine , glycemic , weight loss , endocrinology , glycemic index , respiratory exchange ratio , obesity , aerobic exercise , body mass index , energy expenditure , vo2 max , physical exercise , endurance training , exercise physiology , insulin , heart rate , blood pressure
Objective: To determine the influence of dietary glycemic index on exercise training‐induced adaptations in substrate oxidation in obesity. Design and Methods: Twenty older, obese individuals undertook 3 months of fully supervised aerobic exercise and were randomized to low‐ (LoGIX) or high‐glycemic (HiGIX) diets. Changes in indirect calorimetry (VO 2 ; VCO 2 ) were assessed at rest, during a hyperinsulinemic‐euglycemic clamp, and during submaximal exercise (walking: 65% VO 2 max, 200 kcal energy expenditure). Intramyocellular lipid (IMCL) was measured by 1 H‐magnetic resonance spectroscopy. Results: Weight loss (−8.6 ± 1.1%) and improvements ( P < 0.05) in VO 2 max, glycemic control, fasting lipemia, and metabolic flexibility were similar for both LoGIX and HiGIX groups. During submaximal exercise, energy expenditure was higher following the intervention ( P < 0.01) in both groups. Respiratory exchange ratio during exercise was unchanged in the LoGIX group but increased in the HiGIX group ( P < 0.05). However, fat oxidation during exercise expressed in relation to changes in body weight was increased in the LoGIX group (+10.6 ± 3.6%; P < 0.05). Fasting IMCL was unchanged, however, extramyocellular lipid was reduced ( P < 0.05) after LoGIX. Conclusions: A LoGIX/exercise weight‐loss intervention increased fat utilization during exercise independent of changes in energy expenditure. This highlights the potential therapeutic value of low‐glycemic foods for reversing metabolic defects in obesity.