Comparison of seasonal variation in the fasting respiratory quotient of young Japanese, Polish and Thai women in relation to seasonal change in their percent body fat.
BACKGROUND
From the viewpoint of human physiological adaptability, we previously investigated seasonal variation in the amount of unabsorbed dietary carbohydrates from the intestine after breakfast in Japanese, Polish and Thai participants. In this investigation we found that there were significant seasonal variations in the amount of unabsorbed dietary carbohydrates in Japanese and Polish participants, while we could not find significant seasonal variation in Thai participants. These facts prompted us to examine seasonal variations in the respiratory quotient after an overnight fast (an indicator of the ratio of carbohydrate and fat oxidized after the last meal) with female university students living in Osaka (Japan), Poznan (Poland) and Chiang Mai (Thailand).


METHODS
We enrolled 30, 33 and 32 paid participants in Japan, Poland and Thailand, respectively, and measurements were taken over the course of one full year. Fasting respiratory quotient was measured with the participants in their postabsorptive state (after 12 hours or more fasting before respiratory quotient measurement). Respiratory quotient measurements were carried out by means of indirect calorimetry using the mixing chamber method. The percent body fat was measured using an electric bioelectrical impedance analysis scale. Food intake of the participants in Osaka and Poznan were carried out by the Food Frequency Questionnaire method.


RESULTS
There were different seasonal variations in the fasting respiratory quotient values in the three different populations; with a significant seasonal variation in the fasting respiratory quotient values in Japanese participants, while those in Polish and Thai participants were non-significant. We found that there were significant seasonal changes in the percent body fat in the three populations but we could not find any significant correlation between the fasting respiratory quotient values and the percent body fat.


CONCLUSIONS
There were different seasonal variations in the fasting respiratory quotient values in the three different populations. There were significant seasonal changes in the percent body fat in the three populations but no significant correlation between the fasting respiratory quotient values and the percent body fat.
Graduate School of Human Life Science, Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka, Japan.
Tomoko
T
Morinaka
Malgorzata
M
Wozniewicz
Jan
J
Jeszka
Joanna
J
Bajerska
Porn-ngarm
PN
Limtrakul
Luksana
L
Makonkawkeyoon
Naoko
N
Hirota
Shoko
S
Kumagai
Yoshiaki
Y
Sone
D000273:Adipose Tissue / Q000378:metabolism / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001823:Body Composition / Q000502:physiology*; D002153:Calorimetry, Indirect; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004435:Eating / Q000502:physiology*; D005215:Fasting / Q000378:metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D007564:Japan; D010101:Oxygen Consumption / Q000502:physiology*; D011044:Poland; D012621:Seasons; D013785:Thailand
D004040:Dietary Carbohydrates