Table 1 Personal determinants, methods and description of materials provided to the intervention group.

Awareness of own EBRBs¹ and of interaction between EBRBs¹

Self-monitoring/self-evaluation;

Feedback;

Prompt;

Information delivery.

Tools for personal evaluation;

Active learning strategy.

Box (20*20*2.5 cm), sent by post:

Instruction leaflet including a diary for activities and diet;

Pedometer (advice to take 10.000 steps per day)²;

Waist tape³ to asses waist circumference, with colour indication;

Instrument to easily assess the BMI;

Fruit & vegetable consumption self-test, scratch test format³;

Fat consumption self-test, scratch test format³;

Calorie guide to provide information on the balance between calories of several food products and exercise (minutes walking, swimming and bicycling)⁴.

Knowledge of (own) EBRBs¹.

Information delivery;

Feedback;

Individualised messages.

Internet.

Study website:

• General information and more comprehensive information (after login) on diet, physical activity and the trial.

• Access for 6 months to the Weight Co@ch^®5, an interactive web-based programme providing goal setting on diet and/or physical activity based on individually assessed outcomes [50].

Knowledge of own BMI and standards;

Positive attitude and high self-efficacy expectation with regard to weight gain prevention;

Habit formation with regard to weight gain prevention.

Confrontation with personal risk;

Individualised messages;

Decisional balance;

Skill training;

Goal-setting.

Computer tailoring.

CD-ROM I, sent by post, including manual:

Stage-matched feedback on BMI and statements on EBRB (yes/no), e.g. "Do you consciously watch less television to use that time to be physically active?"

Note that it is stressed not to lose more than 5–10% of initial body weight, unless a physician is consulted.

Knowledge of own EBRBs¹;

Positive attitude and high self-efficacy expectations towards EBRBs¹;

Habit formation with regard to EBRBs¹.

Feedback;

Individualised messages;

Decisional balance;

Skill training;

Goal-setting.

Computer tailoring.

CD-ROM II, sent by post, including manual. All feedback is provided in relation to the guidelines for the behaviour.

Physical activity: minutes per week, based on frequency and duration [65].

Fat consumption: fat score based on fat consumption at cold and hot meals and snacks [66].

Fibre consumption based on consumption and preference for whole grain foods, fruits and vegetables.

Portion sizes of energy dense foods during cold and hot meals, snacks and beverages. Photographs from the EPIC study are used to indicate different portion sizes with permission [67, 68]