If you google “fad diets”, you will eventually run across the tapeworm diet. As it’s name suggests, this diet involves ingesting tapeworm eggs in an effort to loose weight. Now, tapeworms do feed off the nutrients you eat and in theory having a bunch of them in your intestines could result in weight loss, however, this is both disgusting and dangerous. Let’s learn about tapeworms!

What are tapeworms and how do people get them?

Tapeworms are parasitic flatworms. There are over a thousand known species of tapeworm, and at least one of them can infect every known vertebrate animal (vertebrates are animals with a backbone). That includes all birds, reptiles, and fish. Humans can be infected by at least 13 different species of tapeworm. The most common tapeworms in humans are as follows:

• Taenia saginata. The beef tapeworm, which infects humans when they eat raw or under cooked beef.
• Taenia solium. The pork tapeworm, which infects humans when they eat raw or under cooked pork, or if the come in contact with food or water contaminated with pig feces.
• Diphyllobothrium latum. The fish tapeworm, which infects humans when they eat raw or under cooked fresh water fish.
• Echinococcus granulosus. Humans get this from drinking water or eating food contaminated with the feces of infected animals, or from eating raw or under cooked meat.

Raw or under-cooked meat can contain the larval cysts (basically little egg pouches) of tapeworms. When people eat these, the larvae make their way down the GI tract (the tube from your mouth to your anus) and hang out in the intestines. They use hooks or suckers to attach their heads to the wall of your gut, and the rest of their body hangs “downstream” from there. Depending on the species, they can be a few inches long or several feet long. Some can be as long as 50 feet, which is gross. If untreated, they can live for up to 30 years, which is even grosser. While inside you, the tapeworms happily feed off the nutrients in your intestines while releasing a steady stream of eggs into your feces. Ideally for the tapeworm, your feces will end up in water or soil, where they will be ingested by another animal the tapeworm can infect, thus continuing its life cycle. All tapeworms acquired by eating infected meat will end up in the intestines, and when this happens, the infected person is considered a “definitive host,” which means they are the host in which the tapeworm completes its life cycle by producing eggs.

There is another way to get infected by tapeworms, and you are not going to like it. Humans can act as an “intermediate host” for a tapeworm. This happens when people eat the eggs of certain tapeworms that come out of the definitive host, including Taenia solium (the pork tapeworm) and Echonococus granulosus. In this case, the tapeworm eggs hatch in the intestines, but instead of attaching to the wall of the gut and hanging out there, they migrate through the intestinal wall and form cysts (egg pouches, you remember) in other organs of the body – most often the muscle, lungs, brain, eyes, and kidneys. This is a normal part of their lifecycle: generally, they would do this in pigs (Taenia solium) or sheep (Echonococus granulosus), in hopes that these infected organs will be eaten by the definitive hosts (carnivores, including humans) and they could make their way into the intestines of these animals and produce eggs.

When people end up serving as intermediate hosts for tapeworms (some would classify humans as a dead-end host here, because other carnivores are unlikely to eat a person and become infected), bad things happen. These infections are potentially life-threatening, especially when the cysts implant in the lungs, kidneys, or brain.

What are the symptoms of tapeworms?

If you have an intestinal tapeworm, the symptoms can range from nothing at all to more moderate effects like nausea, loss of appetite, diarrhea or constipation, abdominal pain, and fatigue. Weight loss can also occur. In severe cases, infections can lead to vitamin B12 deficiency, malnutrition, allergic reactions, or bowel obstructions.

Things are much worse when tapeworms get outside of the intestines, a condition termed “cysticercus.” In this case, the extent of the problem depends on the species of tapeworm involved and where the cysts ended up. Taenia solium infections of the brain and Echonococus granulosus infections of the lung can be fatal if left untreated.

Maybe the worst idea ever?

Yes, there actually have been examples of people ingesting tapeworms on purpose to lose weight. In one case, a woman reportedly gave it to her daughter to help her loose weight for a beauty pageant. These are examples of terrible decision making! There are serious risks here. Besides the negative effects of an intestinal tapeworm, poor hygeine could potentially lead to other people in the house becoming infected by the more dangerous eggs causing cysticercus. Selling tapeworm eggs as supplements or diet aids is illegal in the United States. Sure, you can probably buy them on the Internet, but do you really trust that you’re not getting the eggs of Taenia solium? These worms could end up in your brain!

There are treatments for intestinal tapeworms, but they are generally not pleasant, involving oral drugs with significant side effects (especially for those with lots of tapeworms in their intestines) and potentially also enema treatments. Cysticercus is harder to treat, depending on where the cysts are located, and could involve surgery.

So don’t take tapeworms to loose weight. If you know someone considering this, or even thinking it might work, do them a favor and let them know the risks. Friends don’t let friends ride the worm!