Phase 1 (Feasibility) completed. Currently no funding to launch Phase 2 (RCT).

In this 3-phase study, following an initial small-scale (phase 1) feasibility trial, the aim of phase 2 of the project is to investigate whether a community-based, 12-month intervention for overweight and obese preschool children 2-6 years of age and their families will be effective in reducing the participants' degree of overweight (BMI z-score) and in improving quality of life.

In the final phase (phase 3), participating children will be randomized to either receiving a multidisciplinary lifestyle intervention during the first 6 months (treatment arm), or 6 months later (control or wait list arm), in order to generate more robust effectiveness data. Participants will receive an additional free 6-month YMCA membership while participating in the study.

Inclusion Criteria:

• Children aged 2-6 on study entry with primary overweight or obesity, BMI => 85th percentile for age and sex on 2010 WHO Growth Charts for Canada
• Family meets Readiness for change criteria, contemplation or higher stage, according to Prochaskas Transtheoretical Model.
• At least one parent/caregiver committed to attend all the program sessions with the child
• Parent/caregiver is agreeing to complete the study questionnaires at the required time points

Exclusion Criteria:

• Chronic medical conditions potentially impacting program participation or associated with a potentially increased risk in participation (e.g. type 1 diabetes mellitus, heart-, gastrointestinal-, or kidney diseases, uncontrolled asthma, other physical, developmental or psychological disabilities that could limit extent of study participation
• Regular use of medications that could limit extent of study participation
• Other concurrent or recently (last 12 months)received obesity treatment
• Inability to read, speak, and/or verbally understand English
• Living outside of the greater London, Ontario, area