Loneliness can be defined as perceived social isolation and appears to be a relatively common experience in adults. It carries a significant health risk and has been associated with heart disease, depression and poor recovery after coronary heart surgery. The mechanisms that link loneliness and morbidity are unclear but one of the mechanisms may be through poor health beliefs and behaviours. The aims of this cross-sectional survey of 1289 adults were to investigate differences in health behaviours (smoking, overweight, BMI, sedentary, attitudes towards physical activity) in lonely and non-lonely groups. Lonely individuals were more likely to be smokers and more likely to be overweight - obese. The lonely group had higher body mass index scores controlling for age, annual income, gender, employment and marital status. Logistic regression revealed no differences in sedentary lifestyles. Lonely individuals were significantly less likely to believe it was desirable for them to lose weight by walking for recreation, leisure or transportation. The findings provide support for an association between health behaviours, loneliness and excess morbidity reported in previous studies.