Fitness and Fat Oxidation in Overweight Chinese, Indian and Malay Men

South Asian men have lower cardiorespiratory fitness (CRF) than white men which is associated with a reduced capacity to oxidise fat during exercise. This is a risk factor for weight gain/regain. Whilst comparisons with Europeans are valuable, Asians are not a homogenous group and substantial differences in obesity and body fat partitioning exist with ethnicity. This cross-sectional pilot investigation aims to compare CRF and fat oxidation at rest and during exercise in Chinese, Indian and Malay men (from Singapore) with elevated BMI (23 -30 kg/m2). Forty-five men (15 each ethnicity) with elevated body mass index (23 -30 kg/m2) will complete testing in a fasted state on two separate mornings separated by ≥72 hours: (i) for a measure of CRF; and (ii) for a measure of fat oxidation at rest and during incremental exercise. A submaximal exercise test will be used to estimate CRF (maximum oxygen uptake, VO2max) during walking using a standard protocol where subjects walk on a treadmill at 5 km/h with regular increments in gradient until individuals reach 80% of their estimated maximum heart rate [220 - age (years)]. Perceived exertion will be monitored assessed periodically during the test and expired gases continuously measured via a mouthpiece attached to an automated metabolic cart (Parvomedics MMS-2400; Parvomedics, Sandy, UT). Oxygen consumption will be extrapolated to estimate VO2max based on estimated maximum heart rate. Resting fat oxidation will be determined via a 30 minute measure of expired gases under a ventilated hood attached to an automated metabolic cart. Fat oxidation during exercise will be determined via walking on a treadmill with increments in speed and gradient until the respiratory exchange ratio is ≥ 0.95. Primary outcomes will be compared among groups and adjusted for any covariates (e.g., BMI, body fat percentage) as necessary.

Inclusion criteria

• male
• age 25 - <45 years
• Chinese, Indian or Malay based on self-identity for three generations (parents and grandparents)
• BMI ≥ 23 - < 30 kg/m2 and/or waist circumference ≥ 90 cm
• physically inactive defined as < 150 minutes moderate or < 75 minutes vigorous leisure-time physical activity per week, or the equivalent combination of both

Exclusion criteria

• females
• personal history of cardio-metabolic diseases
• dieting (i.e. restricting food/energy intake)
• smokers
• consuming alcohol > 3 times per week with > 3 drinks per time
• using any medications which affect carbohydrate or lipid metabolism
• any lower body injuries
• fasting blood glucose > 6.1 mmol/L