we are sentient beings capable of choice, and that this is highly valued, but choices are made in context.
If the context is a community with no fruit and vegetable shops, but a string of fast-food outlets along the high street, then people choose between one form of unhealthy food and another.
If junk food advertising on television and the internet is associated with cartoons and games and hardly any healthy food is advertised, then children choose (demand) this food. If brown bread is three times the cost of white, poorer people will buy the white. The default needs to change so the healthier option is the easier one and only governments can achieve this, through regulation.