P088 ONE DAY OF MODERATE ENERGY DEFICIT SIGNIFICANTLY REDUCES FASTING AND POSTPRANDIAL TRIACYLGLYCEROLEMIA IN WOMEN: THE ROLE OF CALORIE RESTRICTION AND EXERCISE

Rationale: High protein diets have been shown to be effective for body weight loss and weight maintenance, partly through a stimulation of energy expenditure (EE). Gluconeogenesis (GNG) may be responsible for the increased EE after a high protein diet. The objective was to study whether a high protein, carbohydrate-free diet increases GNG and whether this can explain the increase in EE. Methods: Ten healthy male subjects (mean±SEM BMI: 23.0±0.8 kg/m2, age: 23±1 years) received an iso-energetic high protein, carbohydrate-free (H, 30/0/70En% protein/carbohydrate/fat) or a normal diet (N, 12/55/ 33En% P/CHO/F) for one and a half day in a randomized, crossover design while EE was measured in a respiration chamber. Endogenous glucose production (EGP) and fractional GNG were measured using infusion of [6,6H2]glucose and ingestion of H2O; absolute GNG was calculated by multiplying fractional GNG with EGP. Body glycogen stores were lowered at the start of the intervention with an exhaustive glycogen-lowering exercise test. Results: EGP was lower in H than in N (181±9 g/d vs. 226±9 g/d, p < 0.001) whereas fractional GNG was higher (0.95±0.04 vs. 0.64±0.03, p < 0.001) and absolute GNG tended to be higher (171±10 g/d vs. 145±10 g/d, p = 0.06). EE (resting metabolic rate) was increased in H compared with N (8.46±0.23MJ/d vs. 8.12±0.31MJ/d, p < 0.05). The increase in EE was a function of the increase in GNG (DEE = 0.0046*DGNG-0.0021, r = 0.65, R2 = 0.42, p < 0.05). The energy costs of GNG were 27% (95%CI: 5 49%). Conclusion: Increased gluconeogenesis is responsible for an increased energy expenditure after a high protein, carbohydrate-free diet. The energy costs of gluconeogenesis are 27% of the energy content of glucose.