教育介入を行った若年女性の体脂肪率変化は何に支配されるか  [in Japanese] Body fat changes in young Japanese women after educational intervention  [in Japanese]

体脂肪率の変化を左右する要因について季節要因を含めて明らかにするため, 健康な日本人 女子生徒2000年群23名, 2001年群18名, 計41名を対象に介入研究を実施した。2000年は, 1 期 (5月〜7月), 2期 (10月〜12月) とも栄養と運動につき教員主導型の介入を行った。2001 年は, 1期は対象者自主型学習とし, 2期は教員主導型介入を行った。体脂肪率は両年とも1期, 2期の各月初めと12月終了時点にインピーダンス法により測定した。2000年度群は1期で減少, 2期で増加し, 12月の終了時には5月開始時と比較して1.0%有意に上昇した。2001年度群は, 1期において有意に低下, 2期では11月〜12月に平均1.6%有意に上昇した。2001年度群は, 2期に運動, 栄養の両面で積極的に取り組んだが, 教員主導型介入開始時の10月に比べ体脂肪率が上昇しており, 被験者の介入慣れによるモチベーションの低下による体脂肪率上昇ではないことが明らかとなった。両年各対象者の1期・2期の体脂肪率変化率を目的変数とし, 季節, 開始時の体脂肪率, 教員主導の介入の有無, 介入期間中の運動累積指数, エネルギー充足率と栄養密度を従属変数として林の数量化1類と多重ロジスティック回帰分析を行った。いずれの解析においても季節が体脂肪率の変化と最も大きく係る有意な要因であり, 初夏に比較し初冬の体脂肪率増加が著しい。栄養密度高群は低群より体脂肪率が減少しやすい傾向があり, 単にエネルギーを減少させることよりもバランスのとれた食事が体脂肪率の減少に多く寄与する要因であると示唆された。

To identify factors including seasonal variations that influence changes in percent body fat, intervention studies were performed for 2 years. A total of 41 healthy female Japanese college students participated in 2000 (n=23) and 2001 (n=18). Intervention for nutrition improvement and physical exercise were conduced under an initiative by instructors during both the 1^<st> period (May to July) and 2^<nd> period (October to December) in 2000. In 2001, free studies by each student were practiced during 1^<st> period and the same intervention as 2000 was conducted during 2^<nd> period. Percent body fat was measured using bioelectrical impedance at the beginning of each month during 1^<st> and 2^< and > periods and at the end of December in both years. Percent body fat decreased during 1^<st> period and increased during 2^<nd> period, and a significant increase in percent body fat (1.0%) was observed between the beginning of May and the end of December in 2000. In 2001, a significant decrease in percent body fat during 1^<st> period and a significant increase in percent body fat (1.6%) during 2^<nd> period were observed. Although students actively practiced both nutritional improvement and physical exercise during 2^<nd> period in 2001, percent body fat increased and this increase in percent body fat was not due to any decline in motivation. Hayashi's quantification analysis 1 and multiple logistic-regression analysis revealed that only the factor of seasons significantly contributed to changes of percent body fat. Percent body fat increases more in early winter than in early summer. A balanced diet with high nutritional density may help to decrease percent body fat.