OBESITY is the new smoking. That was the blunt message in the latest public health campaign from Cancer Research UK which features the slogan "obesity is a cause of cancer too" emblazoned on a cigarette pack.

It goes on to compares the "extremely effective" marketing tactics used by the tobacco industry to the way items such as takeaway pizza, breakfast cereals and sugary drinks are advertised, reiterating calls for a pre-watershed advertising ban to curtail their appeal to children.

Such an explicit attempt to compare the two has not gone down well with everyone, however.

READ MORE: Depression link to 'brain fat diet'

The temptation is understandable as smoking seems to offer a blueprint to reverse harmful behaviours through effective state intervention, with everything from hefty taxation to plain packaging and advertising bans to restrictions on retail displays playing a role in making smoking increasingly taboo.

A smoking ban might be harder to replicate (people are only allowed to eat chips outside?), but it is just about possible to imagine a scenario where consumers pay cigarette-style duty on their Dominos pizza or buy kilo-bars of Daily Milk in non-descript wrappers from under the counter.

It's extreme, but we live in strange times.

What has really angered the dozens of academics and researchers who penned an open letter criticising the campaign, however, is that it appears to perpetuate weight stigma by telling people "that cancer is their fault" for failing to lose weight.

The fact that the campaign is partnered with Slimming World is also a problematic conflict of interest.

Dr Giles Yeo, a Cambridge neuroscientist and occasional BBC science presenter, was among the detractors. Although he acknowledged that obesity "undoubtedly increases risk of certain cancers", he said it was wrong to draw a direct comparison with smoking because: "people choose to smoke. Obesity is not a choice".

Is he right? Once people start smoking they become addicted - but of course, cigarettes, unlike food, are not required to live.

READ MORE: Majority of expectant mothers now overweight or obese

Then again, many of the reasons that drive some to smoke in the first place - especially stress - also drive them to seek emotional relief in food. It is no coincidence that obesity and smoking rates are both higher in more deprived areas, and a kale salad simply isn't going to cut it.

It is easy to say 'eat less, move more', but countless studies tell us the human body is primed by evolution to regain lost weight.

READ MORE: Weight loss operations down by a fifth in Scotland 

Changing the food environment - something Cancer Research supports - may help, but it probably needs to go much further than portion limits and banning supermarket 'junk food' deals.

Targeting cigarettes was simple.

Without a single smoking gun behind obesity, what do you censure and how?