Low ratio of fat to carbohydrate oxidation as predictor of weight gain: study of 24-h RQ

Am J Physiol. 1990 Nov;259(5 Pt 1):E650-7. doi: 10.1152/ajpendo.1990.259.5.E650.


Reduced oxidation of fat leading to a positive fat balance could be a factor in the development of obesity. Twenty-four-hour respiratory quotient (RQ) was measured in 152 nondiabetic Pima Indians fed a weight-maintenance diet [87 males and 65 females; 27 +/- 6 yr (mean +/- SD); 93.9 +/- 22.9 kg; 32 +/- 9% fat]. Twenty-four-hour RQ varied from 0.799 to 0.903. Prior change in body weight, 24-h energy balance, sex, and percent body fat explained 18% of the variance in 24-h RQ (P less than 0.001). In a subgroup of 66 siblings from 28 families, family membership explained 28% of the remaining variance in 24-h RQ (P less than 0.05). In 111 subjects for whom follow-up data (25 +/- 11 mo) were available, 24-h RQ was correlated with subsequent changes in body weight and fat mass (r = 0.27, P less than 0.01 and r = 0.19, P less than 0.05, respectively). Subjects with higher 24-h RQ (90th percentile) independent of 24-h energy expenditure were at 2.5 times higher risk of gaining greater than or equal to 5 kg body weight than those with lower 24-h RQ (10th percentile). We conclude that in Pima Indians fed a standard diet 1) family membership is the principal determinant of the ratio of fat to carbohydrate oxidation, and 2) a low ratio of fat to carbohydrate oxidation is associated with subsequent weight gain independent of low energy expenditure and may contribute to the familial aggregation of obesity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arizona
  • Blood Glucose / metabolism
  • Body Composition*
  • Body Weight
  • Dietary Carbohydrates / metabolism*
  • Dietary Fats / metabolism*
  • Energy Metabolism*
  • Fatty Acids, Nonesterified / blood
  • Female
  • Humans
  • Indians, North American
  • Insulin / blood
  • Longitudinal Studies
  • Male
  • Respiration*
  • Weight Gain*


  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fats
  • Fatty Acids, Nonesterified
  • Insulin