Fasting respiratory quotient as a predictor of long-term weight changes in non-obese women

BACKGROUND/AIMS: The identification of metabolic and environmental predictors of excess body fat is still far from being achieved. The aim of this study was to evaluate whether respiratory quotient in non-obese women is a predictor of body weight changes after a 6-year follow-up period. METHODS: Forty-three non-obese healthy women participated in the study. Their baseline general characteristics were: age 40.5 +/- 12.8 years; height 159 +/- 7 cm; weight 61.8 +/- 10.1 kg, and body mass index (BMI) 24.4 +/- 3.8 kg/m2. At baseline basal metabolic rate and respiratory quotient were determined by indirect calorimetry, while weight and BMI were recorded at the first observation and after the 3- and 6-year follow-ups. RESULTS: At the first observation basal metabolic rate was 5,360 +/- 713 kJ/day and respiratory quotient 0.850 +/- 0.052. After 6 years, with weight changes equal to 1.4 +/- 4.5 kg, baseline respiratory quotient was a significant predictor (p < 0.05) of changes in body weight or BMI together with baseline BMI. CONCLUSIONS: This follow-up study confirms that a high respiratory quotient (measured on free diet) predisposes to weight gain, especially in women with the highest baseline respiratory quotient (above the 90th percentile of the distribution for this variable).