Seasonal fluctuation in energy balance among farmers in Northeast Thailand: The lack of response of energy intake to the change of energy expenditure

Objective: The study aimed to clarify the seasonal fluctuations in energy b alance and their factors among rice-growing farmers in Northeast Thailand w hose rice production was enough to their food energy demand. Design: Prospective and repeated measurements in the field. Setting: A rain-fed rice-farming village. Subjects: Eight pairs of husband and wife. Interventions: In each of four periods in a year, anthropometry, energy exp enditure survey with heart-rate monitoring and minute-by-minute activity re cording, and food consumption survey were conducted for each subject for 4 days. Results: The change of body weighs was modest but differed significantly (P < 0.001) between pre-harvest and post-harvest seasons: 1.3 kg (2.3%) for m ales, 2.5kg (4.3%) for females. Total energy expenditure (TEE) fluctuated m arkedly between the 4 seasons (P < 0.001 for males and females), but total energy intake (TEI) fluctuated to lesser extents (P < 0.05 for females only ). In relation to energy expenditure, physiological indicators (except resp iratory quotient) did not fluctuate throughout the year but behavioral indi cators did. The changes in body weight were significantly correlated with t he changes in TEE (r = 0.60, P < 0.05 for males; r = 0.83, P < 0.01 for fem ales) but not with the changes in TEI; TEE and TEI were not correlated. Conclusions: The modest seasonal changes in body weight among rain-fed rice farmers in Northeast Thailand were caused by the lack of response of TEI t o the change of TEE.