Influence of vitamin A consumption on resting metabolic rate and fasting respiratory quotient in severely obese subjects.

ABSTRACT

OBJECTIVE: To study whether or not the amount of vitamin A consumed affects the resting metabolic rate (RMR) and fat oxidation at rest in severely obese subjects. MATERIALS AND METHODS: In 239 obese subjects, RMR and fasting respiratory quotient (RQ) were determined by indirect calorimetry. Vitamin A consumption was calculated by the Czech PC program 'Nutrition'. The relation between the intake of vitamin A and RMR and RQ was tested by simple regression. High and low vitamin A consumers were defined by an upper and a lower quintile of vitamin A intake (>842 vs. <382 IU/day). RESULTS: The RMR for high and low vitamin A consumers were 7,693.5 +/- 1,557 and 7,479.8 +/- 1,708 kJ/day, respectively, while the corresponding values for fasting RQ were 0.800 +/- 0.077 and 0.809 +/- 0.049, respectively. No significant correlation was found between vitamin A consumption and both RMR and RQ. Similarly, there was no significant difference in RMR and RQ, as well as weight, body mass index, body fat, waist girth and food quotient between the two groups characterized by high and low consumption of vitamin A. However, the energy intake of high vitamin A consumers was significantly higher than that of low vitamin A consumers, due to higher carbohydrate and protein intake. CONCLUSION: There was no significant correlation between the vitamin A intake and RMR or RQ in obese subjects determined in this study.