The prevalence of obesity in the UK continues to rise. The Health Survey for England 2003 reported that nearly one in four (23%) of men and women were obese, compared to only 13% and 16%, respectively, in 1993. Obesity increases the risk of developing diseases such as diabetes, coronary heart disease (CHD) and some cancers, and can adversely affect the management of these conditions. So there is obviously a major incentive for primary healthcare professionals to support patients in dealing with this important risk factor. In this article, we look at the simple step of encouraging people to control the size of the portions of food that they eat.