Three major dietary patterns are all independently related to the risk of obesity among 3760 Japanese women aged 18-20 years.

OBJECTIVE: To examine associations between dietary patterns and obesity.

DESIGN: Cross-sectional study.

SUBJECTS: A total of 3760 Japanese female dietetic course students aged 18-20 years from 53 institutions in Japan.

MEASUREMENTS: Diet was assessed over a 1-month period with a validated self-administered diet history questionnaire with 148 food items, from which 30 food groups were created and entered into a factor analysis. Body mass index (BMI) was calculated from self-reported body height and weight.

RESULTS: Mean BMI (+/-s.d.) was 20.9+/-2.8 kg m(-2). Four dietary patterns were identified. After adjustment for several confounding factors and total energy intake, the 'Healthy' pattern, characterized by high intakes of vegetables, mushrooms, seaweeds, potatoes, fish and shellfish, soy products, processed fish, fruit and salted vegetables, was significantly associated with a lower risk of BMI> or =25 (odds ratio of the highest quintile vs lowest, 0.57; 95% confidence interval: 0.37-0.87; P for trend <0.05). In contrast, the 'Japanese traditional' pattern, characterized by high intakes of rice, miso soup and soy products, and the 'Western' pattern, characterized by high intakes of meats, fats and oils, seasonings, processed meats and eggs, were both significantly associated with an increased risk of BMI> or =25 (OR: 1.77; 95% CI: 1.17-2.67; P for trend <0.01 and OR: 1.56; 95% CI: 1.01-2.40; P for trend=0.04, respectively).

CONCLUSION: Three major dietary patterns, Healthy, Japanese traditional and Western, were all independently and significantly related to the risk of obesity even among a relatively lean young Japanese female population.