A year ago I managed to persuade my identical twin brother, Xand, to forswear ultraprocessed foods (UPFs) such as pizzas, ready meals, crisps and chocolate on which his diet had relied so heavily and unhealthily for years.
UPFs are essentially industrially produced foods stuffed with sugar, fats and strange chemical ingredients that you don’t find in a normal home kitchen.
At one point Xand hit 19st and that bothered me — not because I cared about how he looked, but because I was worried about what it would do to him in the long term — that he’d die, leaving me to live miserably without him.
So I put him on a sickening binge diet that was 80 per cent UPFs for a week, while he talked to experts about how such products can be addictive and lead to obesity.
What Xand was undergoing was a form of intensive aversion therapy — and it worked well: after just four days he found it almost impossible to eat UPFs.
On the anniversary of that experiment, in a new podcast, I met my brother just before his usual dinner time. I had broken my habit of nagging him about weight but I wanted to see if he could be tempted.
At one point Xand (pictured left) hit 19 st and that bothered me (Chris Van Tulleken is pictured right) — not because I cared about how he looked, but because I was worried about what it would do to him in the long term — that he’d die, leaving me to live miserably without him
I tried to entice him with cookies and chocolate. He threw the packets across the room in disgust. A year ago Xand would have eaten all of those — followed by a takeaway. Nor was this ‘disgust’ just for show. The contents of his fridge and kitchen cupboards have transformed.
Tellingly, one of Xand’s big UPF moments used to be his flights to Canada to see his teenage son Julian. But instead of the usual airport binge — stocking up on crisps and sandwiches — on his most recent trip, he filled two plastic tubs with a cut-up block of cheese and some apples. Even I was impressed. Xand also looks and seems noticeably healthier.
This was a huge success. But Xand is not the only one whose life has changed since investigating UPFs with me.
Last year, for our BBC podcast, I’d consulted Alasdair Cant, a Cambridge-based behaviour-change expert, who explained I had to stop blaming Xand for his high-UPF ways, because I was causing a state of confrontation where neither of us would budge — and this blocked Xand from making changes to get healthier.
On Alasdair’s advice I changed tack completely. I simply let Xand have all the available scientific information about UPFs so that he could make up his own mind.
I know from my own experience how hard it is to give up UPFs — and then to reverse the effects on your body. Last year, for a BBC documentary, I too lived on an 80 per cent UPF diet for a month.
Extreme though it sounds, my UPF diet (and Xand’s) is what one in five Britons consumes every day — and research incontrovertibly shows that it is the main driver of obesity in this country.
After a month, my 6ft frame ballooned: I went from my normal 13 st to 14 st. The weight has gradually been coming off by avoiding UPFs, but over a year later I’m still around 13 st 5 lb.
I read constant claims that all you have to do to lose weight is to stop eating UPFs, but it’s not that simple — not least because of the damage these foods can wreak.
Extreme though it sounds, my UPF diet (and Xand’s) is what one in five Britons consumes every day — and research incontrovertibly shows that it is the main driver of obesity in this country. Xand is pictured left while his brother Chris Van Tulleken is pictured right
Disturbingly, during my experiment my brain began to become addicted to UPFs. An MRI scan showed an increase in the connections between the reward centre and areas that drive repetitive, thoughtless behaviour in just one month.
Essentially I’d become wired for cravings and mindless consumption of food; my brain was telling me to eat UPFs without even wanting them. When we repeated the MRI scan three months later, those addictive brain changes were still there.
Such results made me physically disgusted at the changes UPFs wrought on me, and morally disgusted that people actively peddle this stuff for financial gain.
Disgust is a powerful instinct. So powerful indeed that it stopped Xand and I eating UPFs.
Professor Barry Smith, a sensory expert at the University of London, helped me with Xand’s experiment a year ago. He had previously been advising food-makers on how to make their ultraprocessed products more enticing — looking at crunch, aromas and flavours. He can’t talk much about the specifics of his work, but did you know ice-cream bars have chocolate and caramel perfumes added, as the ice cream itself is too cold to smell but the companies want you to have a sensory hit the moment you unwrap them?
Since the podcast, Barry has had a ‘conversion’ experience, too.
‘I try to avoid eating UPFs,’ he said. ‘And I do not want to work with companies that make this stuff’ — which has meant taking a cut in income. Without his expertise it is harder for ultraprocessed food companies to fool us through packaging, taste and smell.
A year ago I managed to persuade my identical twin brother, Xand, to forswear ultraprocessed foods (UPFs) such as pizzas, ready meals, crisps and chocolate on which his diet had relied so heavily and unhealthily for years
Meanwhile, Professor Rachel Batterham, head of the Centre for Obesity Research at University College London, who performed my MRI scan, has focused her research on the harms of UPFs.
Like many, she’d never heard of UPFs until our experiment. A year on, Rachel said: ‘Thanks to the podcast and the documentary, both my children know about UPFs and both want to cook from scratch, even though such foods are not banned at home.’
The outcomes of my experiment have also changed her research. Earlier this year she published a paper in the journal Nutrients reviewing more than 430 studies on this subject and drawing disturbing conclusions. It showed that UPFs themselves are major obesity drivers — and not (as the industry has consistently argued) that people who eat these foods and put on weight have bad lifestyle habits.
UPFs are ubiquitous. Even our schools are pushing them, with research last month from Imperial College London showing they provide more than three-quarters of the calories in lunches at secondary schools.
Given my strength of feeling about UPFs, you might expect me to call for product taxes. But as a public health doctor I feel they would be unfair because UPFs are majorly targeted at, and consumed by, people on low incomes.Advertising bans, however, would be good — there is no way of justifying marketing these foods to children. The companies aren’t going to go out of business. People have a right to the information to give them the freedom to choose for themselves.
What people need is for food to be better labelled so they know what they are eating and how it is damaging their health.
UPFs can look quite healthy according to today’s labelling systems — which don’t say anything about food processing. For instance, a soya veggie ‘sausage’ might be low in fats, yet is a UPF thanks to flavourings, colourings, preservatives and other chemicals that disrupt appetite and damage our bodies.
The fact is, even in my own home, we still have some UPFs. Banning them entirely for my children, Lyra, five, and Sasha, two, could actually make them want to eat them more.
However, I do buy fewer UPFs and try to tell Lyra they’re bad for her. (As it happens, she says her ‘favourite food is ultraprocessed food and pasta’, so there is some way to go.)
I would like UPFs to become more like cigarettes in terms of the warnings on them, especially as we are increasingly sure the harms are comparable. That doesn’t mean banning them, just making sure everyone has access to information and to affordable, high-quality food. In that regard we have a long way to go in this country.
All this will require understanding and compassion. People still think obesity is due to a lack of activity and willpower, but there is little science to support this.
Many who live with obesity have lost a huge amount of weight many times. But sustaining weight loss is like trying to quit smoking in the 1950s: nearly impossible when surrounded by a deluge of ultraprocessed food and marketing.
As I found with my brother, nagging achieves nothing. If we are going to prevent children being as severely affected, we need to dramatically change their food environment and limit the ability of the companies that sell us food to profit from ill health.
A Thorough Examination With Drs Chris And Xand: One Year On is on BBC Sounds.