Increase in the Thermic Effect of Food in Women by Adrenergic Amines Extracted from Citrus Aurantium

GOUGEON, REJEANNE, KATHY HARRIGAN, JEAN- FRANCOIS TREMBLAY, PHILIP HEDREI, MARIE LAMARCHE, AND JOSEA. MORAIS. Increase in the thermic effect of food in women by adrenergic amines extracted from citrus aurantium. Obes Res. 2005;13: 1187-1194. Objective: To compare the thermic response to a meal between men and women of varied body composition and to determine whether adrenergic amines extracted from citrus aurantium (CA) induce an increase in metabolic rate and enhance the thermic response to the meal. Research Methods and Procedures: In 30 healthy weight- stable subjects (17 women, 13 men; BMI: 20 to 42 kg/m 2 ), body composition was determined by bioimpedance analy- sis followed by resting energy expenditure for 20 minutes, and the thermic effect of food (TEF) of a 1.7-MJ, 30-gram protein meal was determined intermittently for 300 minutes by indirect calorimetry. In a subset of 22 subjects, the TEFs of CA alone and when added to the same 1.7-MJ meal were determined. Blood pressure and pulse before and through- out the studies and catecholamine excretion were deter- mined. Results: TEF was significantly lower in women than men (152 7 vs. 190 12 kJ and 8.8 0.4% vs. 11.0 0.7% of meal), independently of age and magnitude of adiposity. The thermic response to CA alone was higher in men, but, when added to the meal, CA increased TEF only in women and to values no longer different from men. CA had no effect on blood pressure and pulse rate but increased epi- nephrine excretion by 2.4-fold. Discussion: A 20% lower TEF in women suggests a dimin- ished sympathetic nervous system response to meals, be- cause with CA, TEF increased by 29% only in women. However, this acute response may not translate into a chronic effect or a clinically significant weight loss over time.