Yes they should, cancelling meal deals won't solve anything though. The government need to invest properly in infrastructure and services to properly address the obesity issue; but of course they won't, they will just make gestures such as this which do fuck all.
Education of nutrition is genuinely woeful in schools, not the fault of teachers as the curriculum but this should be prioritised in the national curriculum. Yes schools can't do everything and parents need to take responsibility too, but a lot of parents don't have a clue either and pass on unhealthy habits and misguided info. The lessons could be combined with other subjects- again, this should be accounted for in the NC and not added onto teachers unsustainable current workloads.
Poverty is of course a big one and the fact that access to highly processed shit show of food is cheaper and more convenient. The answer isn't as easy as lifting people out of poverty but it would certainly help if decent foods were more accessible and if people had more time than working several jobs to make ends meet.
Cycle paths are often not extensive enough to provide a suitable alternative to driving, gyms often expensive etc- yes running is free and walking is free but it's not always easy for someone to carve out time to do so, especially if they're say a single parent who can't leave the children to head out.
Mental health support needs to improve- a lot of people who are overweight are so due to underlying issues which until they're addressed will continue to cause issues. Also applies to women being taken more seriously in healthcare, things like hormones and thyroid imbalances can cause huge issues with weight but women are too often dismissed.
Obviously loads more but yeah basically the gov won't ever do actual real investment so we will just get more of this banning certain things as a useless token.