Respiratory quotient reduction related to decreased in intra-abdominal fat beyond weight loss

Background

The long-term effect of dietary strategies on changes in respiratory quotients (RQ) and its association with changes in adipose tissue remain unclear. We aimed to assess whether distinct lifestyle strategies can differentially affect RQ and abdominal fat distribution.

Methods

In an isolated workplace with a monitored provided lunch, we randomly assigned overweight sedentary individuals to a low-fat (LF) or an equally hypocaloric Mediterranean/low-carbohydrate (MED/LC) diet for 6-month. Resting metabolic rate (RMR) and RQ was tested by indirect calorimetry. Magnetic-resonance-imaging was used to follow visceral adipose tissue (VAT), superficial subcutaneous-adipose-tissue (superficial-SAT) and deep-SAT changes.

Results

For the entire 159 participants (age=47.7y, 86% men, body-mass-index=31.1kg/m², RQ=0.81, RMR=1929 Kcal/day) body weight decreased by 6.0±4.8 kg after 6-month of diet intervention, similarly between group. The LF group preferentially decreased saturated+unsaturated fats and MED/LC group decreased carbohydrates (P<0.05 vs. other group). The MED/LC diet significantly decreased RQ as compared to the LF diet (p = 0.032). Using multivariate model adjusted for age, sex and changes in RMR and BMI after 6-month, decreased RQ was independently associated with VAT (β=0.144, p=0.027) and superficial-SAT (β= 0.138, p=0.051) reduction. In addition, using similar model, increased in RMR was associated with VAT loss (β=-0.142, p=0.043), and was tended to be associated with superficial-SAT loss (β=-0.129, p=0.090). Changes in DSAT were not associated with 6-month changes of RQ (β=0.065, p=0.29) or RMR (β=-0.057, p=0.41).

Conclusion

During long-term moderate weight-loss intervention, MED/LC diet particularly augments decreases in RQ, a change that was independently associated with VAT loss.