Nick Gibb likes to tell a story about the number of representations he’s received as schools minister. What a lot of them have in common is “the ask”. This is a standard approach - you’re going to see the minister, and no doubt you have fascinating things to tell them. Just one thing. Would they consider doing x? And all too often, “the ask” is “would you put topic x in the curriculum?”

Mr Gibb points out that these asks are almost all rejected, on the grounds that it is not for schools to address these issues. He could also add that given the majority of secondaries and a decent chunk of primaries are now academies, such an ask is increasingly irrelevant. And yet, they keep coming.

A quick Google of “schools should…” gives the following results on page 1: be more active in preventing STDs, teach migrants in their home language, have on-site mental health support, teach more music, do more on special educational needs, protect pupils from air pollution, and watch Euro 2016 during the day (I approve).

The latest successful ask was on childhood obesity. All primaries must now provide 30 minutes of daily physical activity for all children. In contrast to a lot of asks, this one is funded, via the sugar tax. But I still don’t like it. And that’s not because I don’t think childhood obesity is a serious issue, and nor because - let’s not beat about the bush - I was a fat kid at school who hated exercise. (Well, it is partly).

Childhood obesity is caused by a range of factors, including lack of exercise but also poor diet, lack of sleep, poor mental health and genetics. Simply addressing one thing doesn’t work

I don’t like it because it doesn’t work on policy grounds. Childhood obesity is caused by a range of factors, including lack of exercise but also poor diet, lack of sleep, poor mental health and genetics. Simply addressing one thing doesn’t work. Indeed, as most responses to the announcement suggested, primary schools are already doing a large amount of physical activity, and yet obesity rates keep rising.

Secondly, as with anything, this means more work for schools. The opportunity cost of this requirement is huge and - as above - unjustified.

Thirdly, it sets up a “hierarchy of crises”. There’s a long-running campaign to make sex education compulsory within PSHE. So far, the government has resisted. Is this because it has rationally considered the two issues and concluded that obesity is more important than sexual health? It’s doubtful.

And fourthly, I don’t like it because it speaks to what is the deepest philosophical question in education policy - can schools solve society’s issues? Perhaps paradoxically, people who see inequality of education as a consequence of wider societal flaws have always been keen to charge schools with solving them.

By contrast, those who believe in the independent impact of schools have tended to focus - rightly, in my view - on schools’ core role being to educate, and for better life chances to flow from that.

This latter is where the government should be. An obesity strategy - linked to Ofsted, of all things! - is like a dirty burger: best avoided.

Jonathan Simons is a former head of education in the Prime Minister’s Strategy Unit under Gordon Brown and David Cameron