I tend to eat a few protein bars each week – usually on busy days when I don’t have access to a kitchen. As a fitness journalist and coach, I do a bit of everything, but strength training is my primary form of exercise. Given protein’s established role in muscle growth and maintenance, the idea that I can take a 20g stride towards my daily target with a prep-free bar is undeniably attractive.
However, protein bars are also the subject of new Channel 4 documentary Joe Wicks: Licensed to Kill, and the show presents a far less favourable outlook.
On the programme, Joe Wicks and Professor Chris van Tulleken create a protein bar packed with “harmful” ingredients to highlight the perceived hazards of ultra-processed foods (UPFs).
“People eat this food [UPF] because it’s the only food they can afford – it’s sold to them as healthy, and that’s a really crucial part of this programme I’m doing with Joe,” van Tulleken, a professor of global health and infection at University College London, and author of Ultra-Processed People, tells me.
“We’ve picked these bars because they are all sold as being not just healthy, but super healthy, like almost a replacement for real food.”
This stunt has drawn both strong support and opposition. Those in support say it highlights a key issue in our food system; those in opposition have accused Wicks of “scaremongering”. But where do I fall in this debate, as someone immersed in the fitness industry?
What is ultra-processed food (UPF)?
Ultra-processed food is an interchangeable term with NOVA group 4, van Tulleken says. This is taken from the NOVA food classification system, which is used by the likes of the World Health Organisation to monitor global dietary patterns.
For a more accessible definition, he offers the following: “If the packaging you are reading has an ingredient that you don’t typically find in a domestic kitchen, like an emulsifier or a flavouring, then it’s very likely to be an ultra-processed food.”
Products such as crisps, ready meals, sweets, chocolate and fizzy drinks usually fall under this umbrella, as do some less expected items like many kinds of bread. These products make up almost 60 per cent of the average UK diet.
Read more: How politics, ultra-processed food and toxic masculinity are killing the Mediterranean diet
In our discussion, van Tulleken tells me about the ingredients he avoids when buying food for his children. I check the ingredients lists of the protein bars in my kitchen cupboards and several of them – non-nutritive sweeteners, emulsifiers, flavourings and colours.
“Those are the things that allow the food company to tell you a lie,” he tells me. They deliver artificial tastes and textures without the usual, natural cause – for example, sweetness without sugar. He also explains the rationale for companies including these ingredients in products marketed as health-promoting.
The first problem when selling food to elite athletes is that there aren’t many elite athletes in the world, he says. The foods they have historically eaten, such as meat, rice and vegetables, are also commodity foods with a low profit margin.
“Let’s start by saying: ‘anyone who goes to the gym needs special food’,” van Tulleken continues. “Now we’ve got a big market. And let’s create a bar that has a nearly infinite shelf life and uses very, very, very cheap ingredients [that allow us to] make a lot of health claims.
“That’s why the protein bar is the ultimate example of [something with] no real ingredients, a very long shelf life and a very cheap production cost.”
Should you be concerned about protein bars and ultra-processed food?
One of the most common criticisms of the Channel 4 show was that it created unnecessary fear around food. As a health-conscious person, I want the things I eat to fuel and nourish me. As a journalist responsible for sharing health and fitness information, I also don’t want to spread concern unnecessarily.
Alongside a generous hit of protein, van Tulleken argues that many bars – among other high protein products – come with a decent dose of saturated fats, salts and sugars, as well as further ingredients which don’t fit his “found in a domestic kitchen” description.
“I think there are very good reasons to say they will be harmful – they’ll be detrimental to your overall health and your athletic performance because they’re full of so many other things, and because they’re expensive,” he explains.
“[…] What’s the point in wrapping up 19 grams of protein with sugar alcohols, emulsifiers and a bunch of supplements that you can’t absorb, and that aren’t going to do any good?”
This is echoed in van Tulleken’s book, which makes for a persuasive read. A few months ago, it led me to run a test: cut out protein bars and powders for a couple of weeks, then report back on how I felt.
It was far from a closed experiment, with many other uncontrolled variables at play, but subjectively I did feel better; the main differences being less bloating and an absence of stomach aches. I later went back to consuming these products, but at a reduced volume, and I actively sought out more familiar ingredient lists.
Read more: The five ultra-processed food ingredients to avoid on packaging – and what to buy instead
What the science says
The Killer protein bar’s packaging was intended to shock. It states that “excessive consumption may increase risk of diarrhoea, cancer, stroke and early death”, and van Tulleken stresses that each of these claims is supported by multiple cited studies, as well as “a wide body of research linking diets high in ultra-processed food to these same outcomes”.
One citation on the Killer bar’s website classifies the artificial sweetener aspartame as “possibly carcinogenic to humans”. An article from the American Cancer Society reports how “some studies have suggested a possible link, but others have not,” and shares the European Food Safety Authority’s acceptable daily intake (ADI) of 40mg per kilogram of body weight per day.
“A person weighing 70kg would have to consume at least nine to 14 cans of diet soda per day (depending on the level of aspartame in each can) to exceed the ADI,” the article adds.
As is often the case, it appears the dose makes the poison. Moderation would seem to be an effective dietary approach for swerving many downsides to UPF. I put this to van Tulleken when we speak.
“A lot of people online are making this moderation argument, which I totally agree with,” van Tulleken says. “If you smoke one cigarette a month, it won’t hurt you; one glass of wine every few weeks is fine. The problem is that’s not what we’re doing. And that’s the nature of cigarettes, alcohol and ultra-processed food – they are engineered so you over-consume them, and that’s the crucial thing.”
Read more: Scientists reveal the small lifestyle changes that can reduce your risk of heart disease and add 10 years to your life
A second cited study from the European Heart Journal concludes that Xylitol [another artificial sweetener in the bar] is associated with “incident major adverse cardiovascular event risk” but “further studies examining the cardiovascular safety of xylitol are warranted”.
And further referenced research states: “Specific markers of UPFs, such as flavour enhancers, colouring agents and sweeteners, are significantly associated with increased all-cause mortality, raising concerns about the health impact of hidden additives in everyday diets.”
“The findings highlight the importance of looking beyond broad UPF categories to the individual additives driving adverse outcomes. Public health interventions may need to target specific additives most strongly implicated in harm,” it adds.
My main takeaway from this further reading was that the ingredients and nutritional profile of food and drink are what make them harmful, rather than their categorisation as a UPF. The point van Tulleken makes is that the crossover between UPF and harmful ingredients is considerable and can’t be ignored.
This is why he and Wicks are calling for “mandatory warning labels on harmful food” based on the amount of salt, sugar, saturated fat and sweeteners they contain, rather than the level of processing they have been subjected to. This would naturally encompass most UPF, he adds.
Is there a link between UPFs and disordered eating?
On social media, many commenters have suggested Wicks’ ultra-processed protein bar could encourage disordered eating, potentially impacting the eating habits of those already following restrictive diets.
“The risks of demonising UPFs outweigh any benefits of cutting them out, especially when we all know deep down that moderation is key,” one social media user writes.
In an Instagram post about the Channel 4 show, Wicks says that he “made this Killer bar, not to scare people, but to really raise awareness on the topic [of UPF] and to understand just how misleading the health claims on these bars can be”.
Despite his words, it’s hard not to find the bar alarming. The name Killer – derived from references to “killer abs” as a common fitness goal, according to marketers on the documentary – does nothing to dispel the shock factor.
I am not an expert in this area, far from it, but from my perspective fear and food should not coexist. I put this to van Tulleken.
He tells me that both he and Wicks were “very concerned to not drive up rates of eating disorders”, and he has “quite a disordered relationship [with food]” himself. The problems he has encountered always relate to ultra-processed food.
“Food addiction isn’t a formally recognised diagnosis, but many of my patients and friends would say they feel unable to stop eating certain types of food despite knowing it’s harming them – that’s the definition of an addiction,” van Tulleken says. “[…] In my experience, those foods are almost always ultra-processed.”
He believes improved labelling of unhealthy foods could have a positive impact in this area, adding: “I don’t think you drive eating disorders by asking for labelling of unhealthy food – we have no evidence that this is the case.”
Professor van Tulleken references a study published in the JAMA journal earlier this year, which reported that “nutrient warnings performed best compared with other front-of-package food labels types at simultaneously maximising perceived effectiveness and minimising perceived stigmatisation”.
“What makes people feel crappy about themselves and their bodies in this country is a food environment that makes them eat too much harmful food,” van Tulleken argues.
“That is what drives shame and stigma and illness and anxiety and depression. What doesn’t drive the problem is people saying that the food industry needs to be better regulated. That, I feel, is really important; you have to criticise the people who are making the food and the people who are failing to regulate the food.”
Read more: Tim Spector – Joe Wicks’s ‘killer’ protein bar is getting attention, but this is what he’s getting wrong about UPFs
Public health issues vs. personal responsibility
Reading van Tulleken’s book, one of the most compelling sections presented the idea that obesity is a public health issue, rather than the responsibility of the individuals affected. This ties in with his comments above.
What people eat is determined by their budget and the foods that are marketed to them, and UPFs are engineered to drive profits and overconsumption, van Tulleken says.
“We’ve had decades of policies around the world where people have been nudged and pushed and told what to eat and what not to eat. I’ve spent 10 years making programmes where I’m like, ‘Don’t eat chocolate bars. Do eat fresh fruit’. And what happened? Everyone ate more and more ultra-processed food.”
He explains that the UK has a food environment that is unfair for many people. People cannot go home and cook a nutritious stir fry if they don’t have the requisite tools and can’t afford the ingredients; UPF usually represents a cheaper, more accessible alternative.
As someone in the fitness industry, I’ve had myriad conversations with people who say they struggle to eat in a way that supports their health and fitness goals, whether that’s losing weight, building muscle or becoming generally fitter.
There have also been several studies, such as this one in the American Journal of Clinical Nutrition, which found people consistently underreport their calorie consumption. Whatever the cause, there is a disconnect between people’s interpretation of the food they eat and the reality of the situation.
Read more: Experts say including more of this in your diet can help you live a longer, healthier life – and it’s not protein or fibre
Will I give up protein bars?
Joe Wicks: Licensed to Kill and the subsequent Killer bar launch were designed to get tongues wagging. In that regard, the stunt and the show have clearly been successful.
As van Tulleken tells Wicks when he gets cold feet about releasing the Killer bar: “If you run this as a thought experiment, you’re just doing what I’ve been doing for 10 years, and I guarantee nothing will happen.”
The bar is eye-catching, with terrifying terms on the packet which are impossible to ignore; cancer, stroke and early death. These shock tactics are the source of much of the backlash against it.
Many have also argued that the existing UK food environment makes it nigh-on impossible to cut UPF out of your diet entirely, whether that’s down to practicality, impulse or simply because people are priced out of the alternatives. But in conversation, van Tulleken presents his argument, and it is far more nuanced than the packet of a protein bar.
“I don’t tell people what to eat because I don’t know what they can afford or what they like,” he says. “But if you can find a way of eating real food, we’re very sure that’s better for you. You don’t have to believe any of the evidence around ultra-processed food to say that’s true – that’s established in nutrition.”
To achieve this, he recommends asking yourself one question before eating something: “Was this food prepared with the purpose of protecting my health and nourishing me? If the answer to that question is no, then I think you should contemplate if you want to eat it,” he concludes.
So where does this leave me? Disappointed, mostly, that a food environment driven by profit rather than public health has prevailed – a scan of certain supermarket shelves makes this point hard to argue with.
However, I won’t be ditching protein bars entirely. I’ve already cut down since my successful trial earlier this year, and after speaking with van Tulleken then assessing the evidence available to me around UPF, I have been persuaded to be more cognisant of the ingredients in these products. However, they do still represent a practical option on the fairly rare occasions I’m on the go and struggling to find time to eat.
My overarching conclusion is that moderation across the board will usually see you right with your diet, but not even I – I self-confessed fitness fanatic – would watch a documentary a title as vanilla as that.
Read more: I’m a trainer specialising in longevity – these are the five changes that have the biggest impact on my clients
