Fat oxidation at rest predicts peak fat oxidation during exercise and metabolic phenotype in overweight men

• Published in: International Journal of Obesity Vol. 34; no. 5; pp. 871 - 877
• Main Authors: Rosenkilde, M, Nordby, P, Nielsen, L B, Stallknecht, B M, Helge, J W
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-05-2010; Nature Publishing Group
• Subjects: 631/443/319/2723; 692/699/2743/393; Adult; Basal Metabolism - physiology; Biological and medical sciences; Biological oxidation (Metabolism); Blood; Body mass; Body Mass Index; Calorimetry; Calorimetry, Indirect; Cross-Sectional Studies; Diabetes; diabetes mellitus; Epidemiology; Exercise; Exercise (intensity); Exercise - physiology; Fasting - physiology; Fatty acids; Fatty Acids, Nonesterified - blood; Genotype & phenotype; Health Promotion and Disease Prevention; Humans; Internal Medicine; Lipid Metabolism - genetics; Lipid Metabolism - physiology; Lipids; Male; males; Maximum oxygen consumption; Measurement; Medical sciences; Medicine; Medicine & Public Health; Men; Metabolic Diseases; Metabolic disorders; Metabolic syndrome; Miscellaneous; Obesity; original-article; Other metabolic disorders; Overweight; Overweight - metabolism; Overweight - physiopathology; Overweight persons; Oxidation; Oxidation-Reduction; Oxygen Consumption - genetics; Oxygen Consumption - physiology; Phenotype; Physical fitness; Physiological aspects; Public Health; Rest; Rest - physiology; Risk factors; Sedentary Lifestyle; Triglycerides - blood; Denmark; metabolic syndrome; rest; exercise; phenotypes; lipid metabolism; Endocrinopathy; Physical exercise; Body weight; Cardiovascular disease; Lipids; Male; Metabolic syndrome; Overweight; Rest; Adult; Oxidation; Peak; Nutritional status; Human; Nutrition disorder; Prediction; Metabolic diseases; Corporal biometry; Metabolism; Phenotype; Fat; Predictive factor
• ISSN: 0307-0565; 1476-5497
• DOI: 10.1038/ijo.2010.11

Objective:
To elucidate if fat oxidation at rest predicts peak fat oxidation during exercise and/or metabolic phenotype in moderately overweight, sedentary men.
Design:
Cross-sectional study.
Subjects:
We measured respiratory exchange ratio (RER) at rest in 44 moderately overweight, normotensive and normoglycemic men and selected 8 subjects with a low RER (L-RER, body mass index (BMI): 27.9±0.9 kg m
−2
, RER: 0.76±0.02) and 8 with a high RER (H-RER; BMI 28.1±1.1 kg m
−2
, RER: 0.89±0.02). After an overnight fast, a venous blood sample was obtained and a graded exercise test was performed. Fat oxidation during exercise was quantified using indirect calorimetry.
Results:
Peak fat oxidation during exercise was higher in L-RER than in H-RER (0.333±0.096 vs 0.169±0.028 g min
−1
;
P
<0.01) and occurred at a higher relative intensity (36.2±6.6 vs 28.2±3.1%
V
O
2max
,
P
<0.05). Using the International Diabetes Federation criteria, we found that there was a lower accumulation of metabolic risk factors in L-RER than in H-RER (1.6 vs 3.5,
P
=0.028), and no subjects in L-RER and four of eight subjects in H-RER had the metabolic syndrome. Resting RER was positively correlated with plasma triglycerides (
P
<0.01) and negatively with plasma free fatty acids (
P
<0.05), and peak fat oxidation during exercise was positively correlated with plasma free fatty acid concentration at rest (
P
<0.05).
Conclusion:
A low RER at rest predicts a high peak fat oxidation during exercise and a healthy metabolic phenotype in moderately overweight, sedentary men.