To address increasing rates of overweight and obesity, a population-based telephone intervention was introduced in New South Wales, Australia. The Get Healthy Information and Coaching Service[R] (GHS) offered participants a 6-month coaching program or detailed self-help information. Determining the population reach of GHS is of public health importance to ensure that the program reaches disadvantaged groups. This paper describes the socio-demographic and risk profile of participants (n = 4828) in the first 18 months of operations, determines how representative they are of the population, assesses changes in participants' socio-demographic profile and compares "information-only" and "coaching" participants. The results show that GHS users are representative of the adult population in relation to education, employment status, Aboriginal status, fruit and vegetable consumption and alcohol use. However, more female, middle-aged, English-speaking, rural and socially disadvantaged adults participated in GHS. Coaching Participants were more likely to be overweight and to be ex-smokers than the general population. There was substantial variability in GHS recruitment, when mass-reach television advertising was used, participants enrolled from a major city and from more disadvantaged communities. The GHS has broader population reach than many local interventions, but further efforts are needed to increase reach by Aboriginal communities, other minorities and men.