Genetically, Xand and Chris van Tulleken are clones. Yet the 42-year-old twins do not look identical, because Xand is more than 30 pounds heavier than Chris. That is the biggest weight difference recorded in the long-running twin study at King’s College London.
The van Tullekens live in London. They argue about food—specifically, how much Xand eats—all the time. They are also both medical doctors, and they present British television shows on health and diet. In a new podcast, A Thorough Examination: Addicted to Food, they talk with psychologists, nutritionists, behavioral scientists—and their mom and younger brother—to find out how two people with the same genes and upbringing can have such different approaches to food.
Political interventions to combat obesity tend to focus on structural issues such as food deserts, time poverty, and insufficient junk-food labeling, but confronting how food makes us feel is just as important. Food can be joyful and comforting—but also a source of guilt and self-hatred. And because eating is often a shared activity, our consumption becomes interwoven with the dynamics of our families. If anyone understands why discussing our weight with our loved ones can be such a toxic brew of shame, resentment, and frustration, it’s the van Tullekens.
Chris originally wanted to make the podcast to persuade Xand to address his overeating, because he was worried that it was affecting his twin’s health: Both brothers had COVID-19 last year, but Xand became more ill, and the disease left him with a long-term heart condition called atrial fibrillation. However, an encounter with a therapist made Chris realize that Xand wasn’t the only one who had a problem. He did too.
The conversation below has been condensed and edited for clarity.
Helen Lewis: Talking to my family about food sounds like my actual nightmare. Why did you decide to do it?
Xand van Tulleken: Sometimes, if you have a [podcast] producer with you, it allows you to have a conversation that would otherwise be a nightmare. Secretly, our producer was our referee and the both of us in the conversation were like: “Do you see how he is now? Do you get it?”
Lewis: Maybe all the world’s problems could be solved if more people were given a podcast.
Xand: That is the direction we’re going in.
Lewis: In the show, Chris, you describe Xand as seven minutes older chronologically, but 10 years older biologically. What do you mean?
Chris van Tulleken: Because he has lived with obesity, and because he is currently living with being overweight—that ages you. It’s a clumsy phrase, but increased body weight is associated with many of the problems that are also linked to increased chronological age. You end up with the average health measurements, by any metric, of someone around about a decade older.
Lewis: Xand, tell me about when you lived in the United States in your late 20s. Is that when your weight began to diverge from Chris’s?
Xand: I moved to the States to do a master’s degree in public health [at Harvard]. But I was also having a child with somebody, and I was in a stressful situation, because unexpected pregnancies are often stressful. And my response to any kind of stress is to eat. I remember eating almost continuously. So it was stress, and the food environment in America is different. Portions are bigger, and the ingredients are different as well.
Lewis: Chris, you don’t stress-eat, despite having exactly the same genes as Xand. So how much is that biologically determined? Is it just luck of the draw whether you are a stress-eater or not?
Chris: The collision of genes and environment is terribly complicated. We don’t know what conditioning event in our lives means that my response to stress is just entirely stopping eating. It’s probably some weird mixture of childhood experiences and the way our parents treated us, but then in our adult lives, we’ve had these very different relationships with food and weight. Once, Xand was in Sudan, eating a junky diet and probably gaining weight in basically the hottest place on Earth. I went to the Arctic for three months and lost four stone. Maybe those extreme-weight-loss events conditioned me in some odd way.
The thing we have in common is that we both have all the major known genetic risk factors for obesity. Xand and I are enablers of each other: We will go out to a Chinese restaurant and order food for five. We’ve been in restaurants where the waitress has said, “When are the other people arriving?” We both have this very bingeing relationship with food, which is what the obesity genes do.
Lewis: As a woman, I feel like I’ve internalized the idea that I should be anxious about food ever since I can remember. But is some of this harder for men? I have male friends who could eat like a horse in their 20s and were applauded for that—“hasn’t he got a great appetite?”—and then hit 30 and were like, Wait, cheese has calories in it?
Chris: We recorded a bit for the podcast that we didn’t put in. We phoned our younger brother [Jay] in New York. We would go out—not often—the three of us, for a Roman binge. I have always thought of these as quite funny stories: “Remember the time we went to an Italian restaurant and we ended up having to go to Mum’s hotel lobby to be sick?” It was very funny, and anarchic, weird, and transgressive. I phoned Jay and said, “Remember this?” And his response was, “No, that was disordered.”
Lewis: That’s interesting, Chris, because the world says that as a healthy, thin person, you must not have a problem with food.
Chris: As a bloke, no one ever imposes on you the idea it’s a disorder, vomiting after food. I think that is a different experience as a woman.
Xand: We also knew there were things we could be lighthearted about in the recording that the audience would feel differently about because of gender. Being a bigger bloke, it’s not a particularly big deal. No one has ever said, aesthetically, I should lose weight.
Lewis: Xand, is there a particular nightmare to having a thinner twin?
Xand: Everything Chris does well, including being healthy, I look at and go, Well, I can do that. No one else in the world who’s struggling with their weight, unless they’re a twin, has someone else to look at and go, I could be that person. Genetically, that is my possible destiny. It makes me more optimistic.
Lewis: Episode 3 deals with the roles you fell into, the one who is worried about and the one who does the worrying.
Chris: We do polarize each other. I’ll be arguing one thing and Xand will be opposed, and then if I concede and change my mind, he flips. In Episode 3, I listened to mine and my brother’s therapy sessions 30, 40, 50 times to do the editing. The revelation was that I was the problem.
Lewis: Because of the way you nagged and shamed him?
Chris: Yes. Which I thought I’d stopped. When someone else grasps our problem for us, it takes ownership away from us, and doctors do this the whole time. As a clinician, when I see patients I give them advice: stop smoking, lose weight. That can disrupt people from finding their own solution. For Xand to set about losing weight on his own would have been to lose a decade-long argument with me.
Xand: That was how it felt.
Lewis: Xand, you’re educated, and informed about this subject, and yet you couldn’t stop overeating—which suggests that simply raising awareness isn’t the magic bullet here. So what can be done?
Xand: What I loved about this process was that once [the behavioral therapist] Alasdair Cant got Chris not to be a dick about it, once I felt control over it, I realized that the one choice that is definitely good is to not eat ultra-processed food.
Lewis: What is ultra-processed food—and where is it?
Chris: By the end of the podcast, that category of food—you’ll become very aware of it. We have very robust data which shows that obesity is caused by the consumption of this category of food called “ultra processed”: if there is an ingredient on the packet that you do not conventionally find in a domestic kitchen.
Xand: These kinds of foods are lying to you. If you get a pack of instant noodles, it smells and tastes like meaty, nourishing broth. Your brain is expecting amino acids and proteins. But what goes into your bloodstream is sugar and salt. And you don’t feel satisfied.
Lewis: Chris, if you are the thin one in the family, what’s the most useful thing you can do?
Chris: I have a 4-year-old and a 1-year-old, and the 4-year-old watches Frozen on repeat, so when Alasdair Cant said “Let it go,” that resonated. Just stop giving advice. Love your family and leave them alone.
Lewis: And Xand, what should you do if you’re the bigger one in the family?
Xand: So many times over the last few years when Chris and I have been arguing, I’ve just been screaming at him to just be my brother. Maybe I’m overweight, but I’m a bit more relaxed, whereas Chris is slim but a bit more uptight. If you structure your family around the idea that one person has a problem and one person doesn’t, you’re going to be missing what a family is.
Lewis: Should you try to see your family’s nagging as misdirected care?
Xand: That’s impossible. You might be able to do it for 15 seconds, but then you’ll blow your stack.
Chris: You answered this in the podcast. You realized that you had a choice: Oh, I don’t just have to act in opposition. There are some things where I’m in control. I’m not entirely a victim.
Xand: It was a bit about changing the narrative in my head that I’m a victim.
Lewis: Your therapist says at one point that the two of you should remember “this is a love story.” Has making the podcast changed your relationship? I sense you still argue. Do you have better arguments?
Xand: Better arguments is a good way of putting it, but we also probably do have fewer arguments. And it’s not because one of us is shutting up; it’s me going, I think my brother loves me, and it must be difficult worrying about a family member. Maybe that’s the headfake, that I go, Chris has given up [nagging] me, when really Chris spent thousands of pounds on [making] a podcast to change the way I eat, got therapists and scientists from all over the world, and has completely changed what’s in my fridge. All in a way that I feel I took charge of it. Maybe you just have to be clever about the way you manipulate your family.
Chris: One of the really lovely things about the podcast is that my ambition was to change Xand. And when Alasdair said he needed to speak to me, I was really pissed off. “What are you talking about? I don’t have a problem. I have a fat brother.” Then the revelation was: Back off and stop pissing off your family.