BMI is less than 30 kg/m2 or greater than 45 kg/m2

Weight loss \> 10 pounds in past 6 months

Acute or chronic illnesses for which weight loss is contraindicated

Unwilling or unable to give informed consent

Unwilling to accept random assignment

Unwilling or unable to travel to CHP clinic for assessments and groups

Likely to relocate out of the area in the next 12 months

Impact of Group Size in Weight Loss Interventions