A public health expert is calling for the health star ratings on packaged food to be compulsory, but said it needs to be a more rigorous scheme. It's a voluntary system and the most recent figures show an uptake of less than 40%. The government previously said it will look at making the star ratings mandatory if a 70% target is not achieved by November. Nutritionist and co-chair of Health Coalition Aotearoa, Doctor Sally Mackay spoke to Lisa Owen.