thermogenesis (DIT) of specific food items are limited
Methods: In a crossover design, we measured fasting and
postprandial resting metabolic rate (RMR) in 40 men (age =
45.25 years, waist circumference = 108.28 cm) by indirect
calorimetry. Each participant was examined on two occasions,
3 weeks apart. First we measured RMR after 8-hour fasting.
Next, following the consumption of either isocaloric (~380 kcal
each) 56 g walnuts [8% carbohydrates; 84% fat, of which
72% polyunsaturated fat (PUFA)] and 5 slices of whole-grain
bread (48% carbohydrtetes; 32% fat, of which 0% PUFA) we
performed additional RMR measurement. DIT was calculated
as the area under the curve (AUC) of the RMR per minute
of each time point. Abdominal subcutaneous and visceral
fat areas were calculated from magnetic resonance imaging
Results: Fasting values were: RMR = 1,854±205 kcal, RMR/kg =
19.39±1.73 kcal/kg, respiratory quotient (RQ) = 0.82±0.04.
Forty minutes DIT was higher (DAUC = 14 kcal/40min) after
whole grain bread consumption as compared to walnuts
(DAUC = 2 kcal/40min; p < 0.001). Both groups reduced
postprandial RQ (p < 0.001). Those who increased DIT earlierduring digestion had also increased visceral fat content,
increased BMI and decreased RMR/kg (p < 0.05 for all).
Conclusion: High-carbohydrate food induces a greater acute
thermic response when compared to high fat food item.
Visceral adiposity may be associated with a more efficient
processing of food.