p.109 DETERMINANTS OF THE THERMIC EFFECT OF FOOD. uetich JR, Rigberg D, Mullen JL, Banchs RJ, Feurer ID. University of Pennsylvania, Philadelphia, PA, US.

The thermic effect of food (TEF) is an important component of energy balance. The objective of this study was to define the influence of several physiologic variables on the magnitude and duration of TEF.

We employed an S-cage automated rat indirect calorimeter to measure 24 hour energy expenditure (EE) and TEF in 64 Lewis rats. TEF was defined as the increase above preprandial resting EE after ingestion of a balanced liquid meal.

Meal ingestion resulted in a mean increase of 17.9+2.1% above the fasted EE curve, with a return ta baseline by 5 hours postprandially. During this period of TEF, 10.0+1.3% of the kcals ingested were burned. Multiple regression analysis was performed. Independent variables included age in weeks (AG), weight in grams (WI), growth in grams/day (GR), preprandial dextrose (PPD), and kcals ingested (KI); TEF as actual kcals burned in the first five hours of the postprandial period (TEFKCALS) was the dependent variable. The final equation was: TEFKCALS - 1.64 + 1.34(GR) + 0.5(KI) - 0.02 (WI) (R-0.65; p<O.OOl). A significant correlation between AG and TEF was also present (-0.40; p<O.Ol) but a high intercorrelation with GR (r-0.96) resulted in exclusion of AG from the final equation. Preprandial dextrose ingestion did not correlate with TEF. In a separate analysis, extending the preprandtal fast period from 12 to 24 hours resulted in a 56% reduction in TEF (p-0.025).

TEF is markedly influenced by bodyweight, growth rate, fast duration, and meal size. These variables must be considered when evaluating TEF.

P.110 mm3.Y -rxuRE (W AND +SUBlRAm Ul'ILIsATICM IN ?HE CXXIRSE OF RPIVIRITIW OF MAIN(xIRIsMExl f.xILDRpI. J. salas *, E. Rioour. * Pediatria.

Dozio, 0. Goulet, D. Girault, A. Moukarzel, C.

Malades. Paris. France. Divisio VII. Universitat de Harcelona. Spain. Hopital des gnfants

Few studies have dealt with EE during the initial phases of renutrition. The aim of this study was to evaluate, during the child's protein-glucose renutrition phase: a) E!X and substrates evolution b) The relationship between protein metabolism and EE. Material and methods: Seven malnourished children were studied during the first 3 weeks of total perenteral nutrition. Weight-for-Height = 81.4+8.0x t&D,, with an initial weight of 4.49*3.31 KS. Caloric support from carbohydrates only, was progresively increased accor- ding to a pre-established protocol. Every 7 days we determined: a) KK at three different 3-hr intervals per day using an open circuit indirect calorimetric system IMMC-Horizon System): b) Anthropometrically Lean body Mass (LEM); c) 24-hr urinary J-methyl-hyatidine excretion and protein balance. Results: &Yl Day7 Day14 Energy (Kcal/kg/d)

Day21

Supply 57.7f5.6 82.4fY.l 110.8?6.3 106.2+5.4 Expenditure 53.6t4.4 60.9t6.4 73.1f9.1 72.7t9.4 Proteins (gr/kg/d) SUPplY 1.453.18 2.1420.33 2.7320.15 2.60M.13 Oxidation 0.49fo.24 0.69f0.36 1.07kO.32 1.18f0.54 Lipids utilisation (@/kg/d) 1.77f1.2 0.22+1.0 -1.89M.63 -0.9tO.58

Compared to initial values,EK increased 13% at day 7 and 36% at day 14. We found: -1) a negative relationship between the amount of perfused glucose (mg/kg/min) and lipid utilisation (I=-.82;~<.0001) -2) a positive correlation between KK/Weight and protein gain (r=.48;p=.012) and 3-methyl-Hystidine excretion (r=.51;p<.026). Conclusions: The increment of EE in the course of renutrition: 1) Is accompained by the conservation of lipid utilization at a glucose perfusion rate of 14.3 s@/Rg/min. 21 The increment can he partially explained by protein metabolism.

112