An 86-Hour Water Fast Is All Over Social Media, But Is It Safe? (2024)

• UFC president Dana White recently spoke about his 86-hour water fast.
• White says the fast made him feel “like a superhero.”
• Nutritionists advise against trying a water fast like this.

UFC president Dana White is getting plenty of buzz on TikTok after talking up the benefits of doing an 86-hour fast. White had a lot to say about his experience, noting that he felt “like a superhero” afterward.

Worth noting: 86 hours is about three and a half days. “I feel incredible and I want to tell you how I did it. I love sharing this kind of stuff with you,” White said. “When I left the event on Saturday night, I started fasting so Saturday to Wednesday.” White then shared before and after photos of himself, noting that he did a “water fast.”

“Doctors have done studies on this and this thing is legit,” he continued. “It gives you an over 70% chance of not getting cancer, Alzheimer’s, and other nasty diseases.” White later added: “You get absolutely shredded on this thing.”

Meet the experts: Scott Keatley, R.D., co-owner of Keatley Medical Nutrition Therapy; Deborah Cohen, D.C.N., an associate professor in the Department of Clinical and Preventive Nutrition Sciences at Rutgers University School of Health Professions; Keri Gans, R.D., author of The Small Change Diet

White claims the fast has a range of benefits: “Obviously, I’m not a doctor, but I’ve been told by the experts that water fasting can help to significantly reduce the risks of cancer, Alzheimer’s, and a ton of other health issues,” he wrote in the caption of his video.

White isn’t the only person who has tried a water fast recently—TikTok is filled with testimonial videos applauding this method.

But White’s video has raised plenty of questions about what water fasting is and if this is even safe. Here’s what dietitians have to say about it.

A water fast is essentially what it sounds like—you go on a fast, but typically drink water and other no- or low-calorie liquids. There are different versions of water fasts that people have tried, and they often vary by length of time. These are also sometimes used for religious purposes, points out Scott Keatley, R.D., co-owner of Keatley Medical Nutrition Therapy.

White pointed out in his video that this is a variation on a “seven-day water fast,” adding that he was advised that a shorter water fast was a “safer” approach.

“The first 24 hours, all you drink is water—but you can put electrolytes in your water,” White said in the video. (He notes that the electrolyte powder should have no calories.) “The next day, you can have bone broth twice a day for the next two days,” he said.

Nutritionists stress that this is generally not advisable, but safety will vary from person to person. “It’s relatively safe for a healthy individual,” says Deborah Cohen, D.C.N., an associate professor in the department of clinical and preventive nutrition sciences at Rutgers University School of Health Professions. “For those who have diabetes, heart disease, or are prone to low blood sugar or other conditions it can be downright dangerous.” She stresses that people who are pregnant, breastfeeding, or undergoing any cancer treatment or have kidney, heart, or liver disease should not attempt this at home.

“For a healthy individual it might be safe, but still not smart,” says Keri Gans, R.D., author of The Small Change Diet. “However, if an individual is on any medications, they should not try it unless they consult with their primary care physician first.”

While Gans says that someone might lose weight on a water fast, they’re likely to gain it back once they start eating again.

Keatley calls White’s claims “pseudoscience,” saying he’s “cherry-picking vague animal studies,” along with a small study of 52 healthy people. “Extensive, long-term human studies are lacking,” Keatley says. “The danger comes from consuming massive amounts of water with no minerals, which could cause issues with heart functioning."

By the way, Cohen says there is “zero research” to back the claims that water fasts will dramatically lower the risk of developing cancer or Alzheimer’s disease. “If this was true, then those who are starving or malnourished would not ever get cancer,” she says.

Cohen also says that following a water fast could lead to disordered eating patterns and that it’s unlikely to achieve lasting benefits for weight loss. “If this is done to lose weight well, it is not good because it does not teach a person new behaviors or eating habits and does not teach a person how to change behaviors that led to an undesirable weight in the first place,” she says. “In addition, those who are fasting are typically unable to engage in physical activity because no energy coming in.”

While experts don’t recommend doing this, there is some research to support fasting in general. One study published in the journal Nutrients in 2022 had 13 participants do a 10-day fast under medical supervision and found that participants lost weight and achieved a lower blood pressure. They also achieved a “new metabolic homeostasis,” which means their metabolism was able to function at a different level than usual.

A 2023 scientific review published in the journal Nutrition Reviews found that fasting for five to 20 days creates “mild to moderate weight loss” of 2 to 10% of a person's body weight. However, about 2/3 of the weight loss is from lean mass (the other 1/3 is from fat mass). “The excessive lean mass loss suggests that prolonged fasting may increase the breakdown of muscle proteins, which is a concern,” the researchers wrote.

Another 2022 study published in Nutrients on restrictive eating and intermittent fasting—which is not a water fast—found that fasting for 18 hours and eating during a six-hour window causes fatty acids to be metabolized into ketones, which are then used for energy. The researchers also found that this eating pattern increases the chances of weight loss and has been linked to better blood pressure and cholesterol levels. “While more research is needed on longer-term outcomes and this approach should be avoided in particular health conditions, intermittent fasting should be considered as an option for individuals who have a pattern of unhealthy weight gain using standard eating patterns,” the researchers conclude.

Intermittent fasting—which, again, is also not a water fast—has been linked to a lowered risk of developing cancer and slower cancer growth rates in animal and preliminary human trials. However, research into this is ongoing. Animal research has also found a connection between intermittent fasting (not a water fast) and a lowered risk of Alzheimer's disease.

Cohen says that a water fast is “different in every way” from intermittent fasting. “Intermittent fasting is fasting for X number of hours and then consuming some calories,” she says. “This is no calories for more than three days.”

Gans agrees. “While intermittent fasting may limit when you can eat and how much, it still includes actual food in the plan—not only water,” she says.

Overall, experts do not recommend trying a water-fasting diet. “Do not do this unless you are very healthy and are not afraid of being hungry, fatigued, and easily irritable for the duration,” Cohen says.

If you believe you are struggling with an eating disorder and need support, call the National Eating Disorders Association helpline at (800) 931-2237. You can text HOME to 741741 to message a trained crisis counselor from the Crisis Text Line for free.