Is there a scientific basis for the sugar levy?

Discussion of the sugar levy has focused on effectiveness and moral/political hazards. I want to focus on one problem that makes those redundant: Does it make scientific sense?

Not obviously.

A popular narrative: In the past, we thought obese people were that way because they lacked willpower and ate too much food, particularly fat, which obviously made you “fat” – it’s called fat! Then, scientists who had previously been silenced by the nutrition science establishment (which was in Big Sugar’s pocket) bravely spoke up and educated us on the Science!™, and now we know that it’s sugar, not fat, that makes you obese.

Reality is more complicated.

The supposedly debunked “fat = evil” paradigm was never a scientific consensus, but merely a pop-science one. It was less the work of the nutrition scientists than of sugar companies and the makers of low-fat diet products. The supposedly triumphant “sugar = evil” paradigm also has little support amongst nutrition scientists. At best, they are marginally more concerned with the impact of sugar on health than they were 50 years ago, and marginally less concerned about fat.

It isn’t hard to blow the simplistic anti-sugar position out of the water. This graph does it impressively, and should make everyone update their beliefs significantly away from thinking that sugar is a major cause of obesity, and should absolutely torpedo the simplistic “sugar = evil” position that has taken hold in many parts of the population and, seemingly, in government.

A paradigm shift has indeed occurred, but in the popular conception of nutrition science, rather than in nutrition science itself. The pop-science position has gone from simplistically demonising fat to simplistically demonising sugar, with only passing reference to science in the process. This disconnect between scientific and pop-science consensuses is common; explore Scott Alexander’s essay Learning to Love Scientific Consensus for more detail.

Nutrition science is complicated, and individual studies of limited worth. Dishonest charlatans can pull out a few studies, obfuscate their meaning a little, and make it look like the scientific consensus is whatever they want. Only by taking a view of the entire field can one have any hope of making sense of it. The water is further muddied by the state of reporting on nutrition science, which is so bad that media reports of the science often bear no resemblance to the science itself.

If you don’t want to take my word on what the current consensus nutrition science research is, then well done! I recommend starting with Stephan Guyenet’s The Hungry Brain, which provides a solid overview of the current consensus science. If you don’t fancy a whole book, I recommend Alexander’s review of it.

Providing incentive structures can be an effective way to change people’s behaviour, but providing overly simplistic, misguided incentive structures for a system as complicated as this has a long history of producing woeful unintended consequences. Furthermore, awarding the implicit approval of the government to a scientifically unsound oversimplification of a complex field into “sugar = evil” actively harms people’s understanding of nutrition science, making it harder for them to make informed choices.

The sugar levy isn’t just an illiberal, meddling measure to make sure the poor make government-approved trade-offs between the few pleasures available to them – it’s also a scientific nonsense, so we shouldn’t back it.

* Ben Wōden has been a member of the Liberal Democrats since 2010 and lives in Reading.

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  • Could Mr. Woden tells us what his scientific qualifications are and whether he has any connection or interest to declare ?

    Could he confirm why he is satisfied that the American ‘evidence’ he relies on is absolutely impartial and not influenced or funded by any American Corporation ?

    Has he considered and would like to comment on any of the following ?

    Sugar tax: How will it work? – BBC News
    16 Mar 2016 – A new sugar tax on the soft drinks industry will be introduced, the chancellor … The devolved administrations in Scotland, Wales and Northern …
    You visited this page on 03/08/19.
    The UK has introduced a sugar tax, but will it work? | LSHTM…/uk-sugar-tax-will-it-work
    The country introduced its tax on sugar-sweetened beverages (SSBs) in January 2014 to combat its huge obesity crisis – with more than 70% of the population overweight or obese. It placed one peso a litre on all SSBs, as well as an 8% tax on foods high in sugar, salt and fat.

    Food Standards Scotlands response to Soft Drinks Industry Levy ……/fss-response-to-soft-drinks-industry-…
    Food Standards Scotland (FSS) was established by the Food (Scotland) Act, 2015 … have supported application of a broader sugar tax to meet our dietary policy …

  • Paul Barker 7th Aug '19 - 6:14pm

    The article seems to be missing the point.
    We are genetically “programmed” to eat sugar & fats because they are high-energy foods & hard to get under “natural” conditions.
    Our problem is that we live under very unnatural conditions where food is no longer scarce & we don’t have to do much exercise if we dont fancy it.
    The whole point of the sugar tax is that putting sugar in foods (even savoury foods) makes us want to eat them. The tax isn’t aimed at getting us to eat less sugar in itself but less food in general & less processed food in particular.

  • Peter Martin 7th Aug '19 - 8:15pm

    “The sugar levy isn’t just an illiberal, meddling measure to make sure the poor make government-approved trade-offs between the few pleasures available to them – it’s also a scientific nonsense, so we shouldn’t back it”

    This isn’t true. There’s lots of calories in sugar.

    “now we know that it’s sugar, not fat, that makes you obese”

    They both are high calorie so both can make you fat.

    “Reality is more complicated”

    But not that much more complicated.

    Manufacturers are good at putting the right spin on their products. If they are low in sugar but high in fats, or vice versa -guess which one they’ll tell you about on the label!

    The problem isn’t the sugar levy per se. Maybe there should be a fat levy too to make this form of taxation more consistent.

  • Three years into soda tax, sugary drink consumption down more than 50 percent in Berkeley
    Taxes may be a promising new tool in the fight again obesity, cardiovascular disease and diabetes

  • Tony Greaves 7th Aug '19 - 10:07pm

    Why is LDV publishing a series of apologies for the sugar industry? Are the authors all declaring their interests? Just asking.

  • The UK doesn’t currently have a generic “sugar levy”, there is however the Soft Drinks Industry Levy, which seems to have been successful in its public health intent, in that it raised less than half the forecasted tax revenues, mainly due to manufacturers reducing the sugar content in their drinks. Although, I do have reservations about the various sugar replacement additives now being used.

    By not clearly defining what they meant by a “sugar levy” the author weaknesses the article. It is clear the main body of the article is about challenging the pop-science basis of Nutrition Science (talking to NHS nutritionists and they are hard pushed to provide a real scientific-body of knowledge for their work) and the simplistic “sugar = evil” paradigm. From this I infer that what the author is really objecting to is the extension wanted by some to extend the SDIL to food, namely put a levy on (excessive) added-sugars.

    Hence from the argument presented in the article I don’t see it supporting the conclusion that the “sugar levy” is illiberal and scientific nonsense.

  • Excess sugar is bad for you. Sugar taxes are becoming one way of fighting this. Yes there will be a push back against them, but there is always a push back against any measures to improve peoples health ( people don’t like sin taxes of any sort, most smokers I know hate the taxes on tabbaco, the drinkers the taxes on booze).

  • jayne mansfield 8th Aug '19 - 8:16am

    @ Ben Woden,
    The first thing I ask when I see a piece of work, is who produced it, who funded the study and why?

    This graph seems to be a response to the increased use if Acefulsane -K , an artificual sweetener that may be cutting into the sales of sugar.

    Whilst some have chosen to make this about fat shaming, it is nothing of the sort, it is about health and how to maintain healthy arteries to prevent heart disease, stroke and now because current research is demonstrating a link between the health of the cardio vascular system and dementia.

    I would approach this with a concern that sugar producers and corporations have a vested interest in this issue. Don’t you? Whilst there may be merits in promoting the idea that some artificial sweeteners or their components are also damaging to health, as I say, I approach this with a measure of critical thinking.

    Personally, I would put more store by research from professionals who researchers who are working in the field, those working within the American Heart Foundation, the British Heart Foundation etc., with the same critical awareness, but whose vested interests are more likely to be a search for pushing the boundaries of knowledge and the causes of ill health. If education is the answer, who should be doing the educating and what should they be teaching? That education should take place before potential damage is health occurs whereas at the moment, individuals only realise that their health has been damaged when the damage has been done and sometimes the only response possible is to give education too late so that mitigates the effect of further damage.

    Who do you think most benefits when this issue is turned into a ‘fat shaming’ issue’, and therefore something not to be discussed or investigated?

  • Nonconformistradical 8th Aug '19 - 9:16am

    Is this the author?

    In which case he appears to be doing a PhD at Reading (fits with his location) and appears not yet to have completed it – and it appears to be in an unrelated area of science.

  • Are we meant to take seriously the graph? There has been a small change in sugar consumption over a period chosen by those who published it. There is a large and increase in obesity.
    I have seen no evidence that the high consumption of sugar is not an important factor in the increase in obesity and various chronic conditions. I have seen no claims that it is the only one.
    Surely a LibDem audience is expert in is how to select statistics to support a case?

  • Funny, buy did the research take into account sugar derivatives which companies have been using more and more.

    I have noticed over the last 10 years foods that never contained sugar now contain sugar. Those foods have dropped out of my shopping list and as each year goes past more have been dropped out if my shopping basket.

    Sugar derivatives in bread have been increasing, I have stopped purchasing bread now. Last time I brought commercial bread was 5 years ago.

    If you look at ingredients you will see inverted syrup, dextrose etc… These are all sugars which companies are using to replace the word sugar in their ingredient lists.

  • Callum Robertson 8th Aug '19 - 12:08pm

    I must confess, Tony’s comment (akin to that of a “who funds you fanatic on twitter”), is rather odd. Surely we are not at a stage in the party where we are decrying people for having a differing opinion on a policy issue.

  • Laurence Cox 8th Aug '19 - 12:25pm

    Or the causes of obesity are more complex than Ben Wōden suggests. For example, this article in Nature implicates both diet and the gut biota. If eating too much sugar in childhood causes obesity by affecting the gut biota, then one would expect to see adult obesity increasing long after sugar consumption declines, just as increases in lung cancer long postdated increases in smoking.

  • At the end of the day we will never be able to pin the blame for obesity on one macronutrient. Even for constituents of food that are demonstrable unhealthy.

    If we’re really interested in solving the obesity crisis (including the heart breaking child obesity stats) , then I suggest we begin by addressing income inequality, poverty, marginalisation, and austerity.

    Obesity, much like addiction, is to some extent a disease of despair.

  • Brian Robinson 8th Aug '19 - 2:51pm

    The graph is highly misleading. A decrease in sugar intake in the population as a whole, while obesity has continued to increase, does not mean sugar is “innocent” – it may be, but the graph does not prove it, as the author seems to think.

    Thus the conclusion that the graph “should make everyone update their beliefs significantly away from thinking that sugar is a major cause of obesity” is not reliable.

    Consider this alternative explanation. Sugar has been identified as a possible problem, so “sugar-wary” people have decreased their sugar intake considerably. As a result, sugar intake as a whole (in the US) has decreased. Meanwhile, others have continued to consume lots of sugar, possibly contributing to rising obesity levels.

  • I can’t help wondering what scientific background all those criticising Ben Woden have?

  • I think a few comments merit a reply:

    I think it’s important to look at how science is funded. Of course the sugar industry has an interst here, as do many other powerful groups. However, beware isolated demands for rigour. Being industry-funded doesn’t make science worthless, it just means we shouldn’t take it on trust. There’s a disturbing trend in which people apply very high standards to evidence that goes against their current views, while being very lenient to anything that supports their existing views. Scott Alexander’s essay here ( is a fantastic introduction to the phenomenon.

    The only solution is to look to the current scientific consensus (NOT the popular science narrative – again I cannot reccomend Alexander’s essay enough ( and that scientific consensus says that sugar is as dangerous as it is calorific, not to any additional degree.

    Had I written this just a day later, I’d have linked to this Nature paper ( It’s a huge review of the evidence on whether sugar in particular contributes to obesity, diabetes, cancer, cardiovascular disease, and some other things. It finds in every case that sugar is no more dangerous than any other source of calorific value.

    That graph was complied by Stephan Guyenet, a leading neuroscientist of nutrition. Some pointed out that it doesn’t disprove a link between sugar and obesity. Correct. The idea of presenting that graph wasn’t to prove beyond all doubt that sugar is related to obesity. It was designed to prompt a “hmm, well, it’s a lot more complicated than I thought” response, that would prompt further enquiry and investigation. It should also make any rigorous Bayesian updater downweight their credence in sugar-based explanations of obesity, as it’s just not the kind of data you’d be *likely* to observe if sugar was the major cause of obesity.

    In all, I’m really pleased that this has generated some response and got people thinking beyond the simplistic pop-nutrition paradigm on this issue. That’s what I want! Go read The Hungry Brain, go read that Nature paper, go investigate the literature for yourself and see what you find. I’m also happy if anyone takes this as a prompt to read any of Scott Alexander’s excellent essays :p

  • @Mat I have noticed over the last 10 years foods that never contained sugar now contain sugar.
    Yes, it is a big, problem, however, if you are watching sugar intake with respect to regulating blood sugar levels, you also have to note the carbohydrate content. With some products I buy the high fat variant because it has significantly lower carbohydrate/sugar content than the advertised “low sugar”/”low fat”/”low cal” version. [Aside: a friend’s son regularly visits (to see my son and play on the Xbox…) and his mother has given us a strict list of things he likes and can eat that won’t require balancing out with large doses of insulin; her decision to manage things through diet does seem to be working. Applied it to myself and lost 2 stone in a couple of months.]

    WRT Bread, do you make it yourself now or have you found a local artisan baker?

  • James Belchamber 9th Aug '19 - 1:32pm

    This is an impressive pirouette around the only answer to the question posed: Yes, yes, definitely yes.

    The scientific consensus is that over-consumption of sugary drinks is a major contributor to obesity, and that a sugary drinks tax is an effective tool in reducing their harm. There have been many studies and The World Health Organisation wrote a well-sourced pamphlet (and they’re not exactly in the business of bad science):

    I appreciate the Liberal need to justify infringements on liberty, but let’s not engage in intense cherry-picking in an attempt to blind ourselves to it. The consensus amongst experts in this field is that a sugary drinks tax is long overdue, that it’s working as intended, and that we need to go further to reverse decades of profit-driven over-consumption.

  • Brian Robinson 9th Aug '19 - 2:56pm

    @Ben Woden (your reply, not the original article) – you say the graph is not meant to prove “beyond all doubt” that there is no link between sugar and obesity, but that “it’s just not the kind of data you’d be *likely* to observe if sugar was the major cause of obesity”.

    However, in making that claim about likelihood you have allowed yourself to be misled by the graph: it’s possible, perhaps even likely, that while people suffering from obesity tend to consume large amounts of sugar, reduced consumption by *other people* explains the fall in consumption in the population as a whole.

  • Jayne Mansfield 11th Aug '19 - 9:18pm

    @ Ben Woden,

    Nature is a prestigious science magazine, so one has to take seriously the acceptance of a paper by Philip Prinz: The role of dietary sugars in health : molecular composition or just calories?.

    However, how did the other expert you quoted Stephan Guyanet respond when it was pointed out to him that that Philip Prinz was an employee of the German Sugar Association. There is a reason why at the end of the paper, an ethics declaration is required.

    Let us look at what one of your chosen experts said.

    ‘Thanks for pointing that out , it does undermine the paper. I have to say though that any reasonable person reading the lit would conclude that the impact of sugar on body weight is mediated by calories. May not be entirely true of CVD and T2DM though’.

    James Belchamber questions your view on the scientific consensus on sugar and its effect on health. It does seem that if one is looking for bias when it comes to cherry picking scientific research findings, political bias seems to play a too large, unwelcome part.

    @ Martin,

    I can’t think of a more effective way of sending someone with a weight problem to the biscuit barrel than so called ‘fat shaming ‘ them. Certain foods, and certainly sweet sugar laden foods etc., are often part of a ‘reward system’ when one feels low, stressed, depressed etc., and in need of a short term boost. Non- judgemental support and education that helps individuals exert control over the health of their own bodies, achieve outcomes that they themselves want, is, I would argue, more likely to be effective.

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