There isn’t much to be cheerful about in Britain right now. Summer has come to an end. The government is in chaos. And who knows what’s happening with Brexit.

Now, we may face further restriction on our last remaining pleasure: sugar. Today, the British Medical Journal published a study recommending a 20% ‘snack tax’ on sugary treats. Combined with Brexit, it’s all too easy to imagine a future in which canned food is our only comfort.

In all seriousness, there are some solid arguments behind a snack tax. According to the study’s researchers, increasing the price of biscuits, cakes, chocolates and sweets by 20% would reduce annual average energy intake by about 8,900 calories. Which could result in the UK’s obesity rate falling from approximately 28% to 25%.

That’s all an estimate, of course, but an educated one. The soft drinks levy is proof that UK consumers do respond to price increases. Sales of diet drinks soared 13.8% to 1.7 billion litres in the wake of the sugar levy [Kantar 48 w/e 24 February 2019]. By contrast, volumes of regular fizzy pop fell 8.8% to 823.6 million litres.

So a snack tax may seem a sensible way to stop Brits scoffing sugary cakes and biscuits by the bucketload. Still, this idea creates more questions than it does answers.

In the case of soft drinks, the clear issue was sugar. So the taxable criteria – 18p per litre for drinks containing 5g to 7.9g per 100g, and 24p for anything containing 8g or more – were fairly simple. The study suggests applying the same sugar-centric approach to snacks. But in this market, there are more variables to consider. Will fat be a consideration? How about calorie content? And what happens to fruit-based snacks that are positioned as healthy, but contain a high amount of fructose?

There is also the issue of portion size. Would an 18g Cadbury Freddo be subject to the tax? Because it may contain 11% sugar but, in such small quantities, that only equates to 10g. (Admittedly, that’s still a third of an adult’s recommended daily limit.)

Plus, it’s important to look at what’s on offer. In the soft drinks market, diet alternatives to sugar-laden beverages were already well established before the sugar levy came along. Crucially, manufacturers had arrived at the point where there was little, if any, compromise on taste.

In snacking, there is little in the way of similar options. Yes, there are healthy snacks – but these tend to taste very different to your standard chocolate bar. So will consumers be deterred enough by the 20% tax to opt for these instead? The likes of Nestlé and Mondelez are dabbling in reduced-sugar chocolate, but the concept is still in its infancy.

Finally, any such tax would need the backing of Boris Johnson, who is famously averse to “sin stealth taxes”. Although given the current state of affairs, it may not be his decision for long.