Doctors Do Own Research

Xand and Chris van Tulleken, the very media-savvy twin doctors with weight issues, have a complicated history regarding both obesity and each other. Xand was initially the identified patient. This video is a very brief teaser, mentioning how, during a stressful period of life, he woke up one day weighing 19 stone, the equivalent of 266 pounds.

Now, over to Dr. Chris, who once said of his brother,

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.

This may or may not have been related to the experiment that Dr. Chris put himself through, or as phrased it, “the 42-year-old doctor did his best to test a theory and experimented on himself.” For four weeks, he assigned himself the task of following a diet based on 80% ultra-processed food. In another video, he explains that the parameters of the experiment included permission to eat whenever he felt hungry.

Cinéma vérité

There is a scene where Dr. Chris pores over the long list of unpronounceable ingredients printed on a food package, and another of him at 4 AM saying, “I’ve had to come to the kitchen. I can’t sleep. I’ve got heartburn. I’ve got a headache. I feel like eating more food.”

Over the month, his weight increased by 14 pounds. Imagine gaining 14 pounds a month for, say, a year! In the United Kingdom, no imagination is needed, because one person in five stays on 80% processed food, all the time. Even the obesity expert who worked on this project became more aware about feeding her kids.

At any rate, all the on-demand banquets of hyper-processed food culminated in “constipation, insomnia, anxiety, heartburn, headaches, rapid weight gain, mood swings…” and other problems. The sensation of waking up feeling hungover was an additional drawback, and even a diagnosis of addiction seemed plausible.

During the experimental month, blood tests showed that Dr. Chris’ fullness hormone decreased while his hunger hormone increased by 30%. MRI scans revealed that “following a diet high in ultra-processed foods connects the reward centers in the brain with the areas that drive repetitive automatic responses.” The experimenter/subject said,

My diet has linked up the reward centers of my brain with the areas that drive repetitive automatic behavior, so eating ultra-processed food has become something my brain simply tells me to do without me even wanting it. says,

[D]espite a keen professional awareness of the harm he was doing to himself, van Tulleken declared himself quite incapable of controlling his excesses with food. In fact, he stated that despite feeling that he was no longer enjoying food, he could not stop and that is why he directly related the consumption of ultra-processed foods with a powerful addiction.

Anyway, the conclusion was, “I have aged 10 years in four weeks.”

Your responses and feedback are welcome!

Source: “My Weight Loss Story by Dr Xand van Tulleken,”, 01/03/17
Source: “Here’s what happens after a month of eating only ultra-processed,”, 05/24/21
Source: “UK doctor switches to 80% ULTRA-processed food diet for 30 days,”, undated
Image by Rawpixel Ltc/CC BY 2.0

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OVERWEIGHT: What Kids Say explores the obesity problem from the often-overlooked perspective of children struggling with being overweight.

About Dr. Robert A. Pretlow

Dr. Robert A. Pretlow is a pediatrician and childhood obesity specialist. He has been researching and spreading awareness on the childhood obesity epidemic in the US for more than a decade.
You can contact Dr. Pretlow at:


Dr. Pretlow’s invited presentation at the American Society of Animal Science 2020 Conference
What’s Causing Obesity in Companion Animals and What Can We Do About It

Dr. Pretlow’s invited presentation at the World Obesity Federation 2019 Conference:
Food/Eating Addiction and the Displacement Mechanism

Dr. Pretlow’s Multi-Center Clinical Trial Kick-off Speech 2018:
Obesity: Tackling the Root Cause

Dr. Pretlow’s 2017 Workshop on
Treatment of Obesity Using the Addiction Model

Dr. Pretlow’s invited presentation for
TEC and UNC 2016

Dr. Pretlow’s invited presentation at the 2015 Obesity Summit in London, UK.

Dr. Pretlow’s invited keynote at the 2014 European Childhood Obesity Group Congress in Salzburg, Austria.

Dr. Pretlow’s presentation at the 2013 European Congress on Obesity in Liverpool, UK.

Dr. Pretlow’s presentation at the 2011 International Conference on Childhood Obesity in Lisbon, Portugal.

Dr. Pretlow’s presentation at the 2010 Uniting Against Childhood Obesity Conference in Houston, TX.

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