Obesity rates are growing at an alarming rate and new solutions are urgently needed (WHO, 2010). This thesis aimed to explore the potential to translate some of the lessons learnt from the UK’s successful tobacco control approach to combating obesity, using Self Determination Theory (SDT, Ryan & Deci, 2000) as a theoretical framework to explore the mechanisms of policy level factors influence on individual motivation. This was explored in three studies using a mixed methods approach. Qualitative Study 1 aimed to explore people’s experiences of tobacco control and obesity policies. The results suggest that current tobacco and obesity policy climates are perceived as controlling and are not perceived as motivating for behaviour change. Study 2 tested the hypothesis generated in Study 1, that exaggerated images (i.e. morbidly obese figures) accompanying articles about the health risks of being overweight would prevent overweight people from identifying with these risks. The results demonstrated there was no effect on identification with the message, however such images cause individuals to visually underestimate the level of obesity associated with health risks. Study 3 pilot tested a campaign-style intervention which was translated from the tobacco domain. It involved a snack-swapping intervention designed to help people to increase their fruit and vegetables intake while supporting their autonomous motivation, and aiming to provide an online environment to normalise this aspect of healthy eating. Participants had higher intake of fruit and vegetables as a results of taking part in the intervention, however their intake of unhealthy snacks was not reduced. Applying SDT as a theoretical approach was useful as a means of understanding people’s responses to legislation, however the results emphasized challenges in implementing strategies which aim to create autonomy supportive climate at public policy level. New insights for policy development stemming from the three empirical studies have been outlined.