This Doctor Swallowed a Tapeworm—For Science

These days, it’s hard to tell which health claims are and aren’t true. We grew up being told to avoid fat at all costs, but now high-fat diets are all the rage and sugar is the bad guy. Different documentaries and health articles constantly contradict each other—just look through Netflix’s food documentary selection and you’ll feel confused as hell.

Dr. Michael Mosley—the same man who popularized intermittent fasting—will do anything to get to the bottom of things. On his BBC show Infested, he swallows tapeworms and a pill camera to study the effects of tapeworms on the human body.

The pill camera Dr. Mosley uses takes about 16 pictures a second, and transmits them to his iPhone. After swallowing the camera, he maneuvers it with a magnet, and it passes through his system within 30 hours, taking photos all the while.

“What I was interested in was the effect of the tapeworm on my immune system. We know that in parts of the world where there is lots of infection with worms, people do not get allergic diseases like hay fever, asthma, and eczema, whereas in places where we got rid of the worms, these things are on the rise,” Dr. Mosley says.


He observed that while he had a bad case of hay fever, it went away when he was infested with tapeworms. “What the worms do is they help to switch down the immune system,” Dr. Mosley explains. “But there are easier ways of doing it than getting infected with worms: eating the sort of foods that good bacteria in your gut like. A lot of the [fermented] Asian foods such as kimchi can be very healthy for the gut bacteria, but what the gut bacteria really love is fiber in all its different forms. If you could get more fiber in your diet, then that would be a very good thing.”

Together with a team of physicians, Dr. Mosley investigates all kinds of health claims on another BBC show, Trust Me, I’m a Doctor. “The reason we call it Trust Me, I’m a Doctor is because we put a lot of time and a lot of money into researching the things that we do,” he says. “You see us presenters talking and doing demonstrations, but there is a huge team behind that who are doing the research and are looking into the facts. We have a lot of people with PhDs and further degrees, and we also have access to a lot of experts. So we’re very careful about what we do. We also do our own original research and check it with experts.”

One of the things Dr. Mosley demonstrated on the show is how the idea of doing 10,000 steps a day to stay fit is a myth. He claims that the idea was invented by a Japanese marketing company during the Tokyo Olympics, since they had a pedometer they wanted to sell.

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“[What] you should know about these things is they lie,” he says. “When they tell you you’ve burned thousands of calories, it’s just not true. They grossly exaggerate, they’re incredibly inaccurate. They’re quite accurate at measuring steps, they’re really really bad at measuring calories. Do you know how far you would have to run to burn one kilo of fat? About 100 kilometers. When you go for a walk you burn about 30 calories a kilometer. So if you had a small bar of chocolate with 240 calories, you’d have to walk about eight kilometers to burn that off. So exercise is good, but it’s not a good way of losing weight.”

On Trust Me, I’m a Doctor, the team asked factory workers to either do 10,000 steps a day, or three ten-minute brisk walks, and gave them monitors to measure the impact on the workers’ health.


“The three brisk walks are about 3,000 steps in all, but they’re much more effective in improving the health of the people because it’s more achievable,” Dr. Mosley asserts. “There’s better benefit because it’s not how about how far you go but how hard you push yourself. It’s about getting your heart rate up. So when I see people jogging along, I want to shout at them, ‘RUN! RUN!’ Even if it’s only for a hundred meters, there’s so much more benefit from sprinting than running a mile at a slow pace.” 

Navigating diet fats and conflicting health claims may be overwhelming, but you can rest assured that the team behind Trust Me, I’m a Doctor is dedicated to presenting the real facts. “What I do is based on science. When I write books, I write all the scientific references,” Dr. Mosley says. “I have support from Nobel prizewinners. I feel ironclad. I’m very happy to debate with anyone anytime about science.”

Infested premieres tonight at 6:20 p.m. while Trust Me, I'm a Doctor airs on April 16, 10:50 p.m., both on BBC Earth (Cignal Channel 245). 

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Angelica Gutierrez
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