At inclusion, participants completed a set of five questionnaires related to sociodemographic and lifestyle characteristics (eg, date of birth, sex, educational level, smoking status, number of children), 31 anthropometry (height, weight), 32 33 dietary intakes (see below), 34 35 36 physical activity (validated seven day International Physical Activity Questionnaire), 37 and health status (eg, personal and family history of diseases, menopausal status, drug use including hormonal treatment for menopause and oral contraceptives). Weight was collected every six months. The web-based self administered anthropometric questionnaire was compared with a traditional paper questionnaire, 33 and reported weight was also validated against weight measured with a calibrated scale (BC-418MA, TANITA, Tokyo, Japan) by trained investigators in a validation study on a subsample, 32 showing high consistency. Other web-based questionnaires used to collect baseline characteristics of the participants (eg, sociodemographic and lifestyle data) have also been tested against traditional paper questionnaire, 31 showing very high consistency between the two methods, and even a lower proportion of missing or abnormal values in the web questionnaire, owing to integrated controls, mandatory fields, and conditional skip patterns. Other methodological studies were conducted to test for the reliability of the data declared online by the participants and also observed very high levels of consistency. 38 For instance, the consistency between declared information on sex, date of birth, and department of birth of a sample of participants and the first digits of their social security number was checked.