In a popular 2023 Instagram reel, Dana White, the president of the UFC, said he’d recently done an 86-hour fast, and he ‘[felt] like a superhero.” Let’s note that 86 hours is more than three and a half days. The video left a lot of people wondering if they should try a similarly long fast for themselves.
In this article, we’ll discuss the science behind long-term fasting, the risks and potential benefits, what an 86-hour fast is, and how to do it, so you can decide for yourself whether you should try it. But the short answer is: You probably shouldn’t! Here’s why.
What is a water fast?
A water fast means you drink water during the fast, even though you don’t eat food. This is in contrast to a dry fast, where you avoid water. Dry fasting can only be done for short periods; it risks dehydration and serious health effects and could result in death if done for such a long period as 86 hours.
In Dana White’s version, you can drink only water for the first day (“but you can put electrolytes in the water,” as long as they have zero calories). After that, “you can have bone broth twice a day for the next two days.” This makes the fast slightly easier since you’re getting a small amount of food instead of none at all.
How do you do an 86-hour fast?
It sounds simple to accomplish — don’t eat any kind of food for 86 hours. However, actually accomplishing the task requires some strategy. You don’t think or work your best when you’re hungry, so you should schedule this fast for a time when you won’t have to be at work for most of the fasting period, such as a long weekend.
For example, you could start your fast on Friday at about 5 p.m., just after eating dinner, and eat again at 7 a.m. on Tuesday, 86 hours later. Your breakfast on Tuesday will help you feel prepared for work. Aim for a large and healthy breakfast, balanced and full of foods that give you energy, with lots of protein, fruits and vegetables, and carbs.
What are the claimed benefits of an 86-hour fast?
Weight loss
One of the major claimed benefits of long periods of fasting is that they will help you lose weight. It is true that fasting for at least a day at a time has proven weight loss benefits, even more than intermittent fasting. However, there is some concern that when fasting for periods of multiple days, you may just eat larger meals afterward and regain the weight. Some studies suggest that weight loss could be maintained, but they still say that any metabolic effects quickly disappear after a fast ends.
Immune system boost
Long fasts have been shown to increase the immune system’s sensitivity when it has been suppressed, such as through chemotherapy. However, there is currently no evidence that fasts can improve the immune system of people who are not compromised. This is still the subject of many studies and may change.
Potential reduced risk of cancer
This is the most dramatic claim Dana White makes in the video: “[This fast] gives you an over 70% chance of not getting cancer, Alzheimer’s, and other nasty diseases.” It’s unclear exactly what he means by that — do you have a 70% lower risk than other people, or do you have a 70% chance of not getting cancer while others only have a 65% chance? It’s always important to understand what claims statistics are meant to support.
Based on a scientific summary, fasting for long periods can reduce some of the side effects of chemotherapy and increase its effectiveness, which suggests that fasting may have an important part to play in treating cancer patients. However, there isn’t currently any evidence that it reduces the risk of healthy individuals getting cancer in the future, although research is still being done. At the moment, White’s claim is, unfortunately, not supported.
What are the potential risks of water fasts?
Lack of energy
A long fast can leave you feeling drained and result in difficulty doing ordinary activities. It’s not recommended to work out during an 86-hour fast since you’ll end up draining yourself even more. This is common even with intermittent fasting and is much worse on a complete fast.
Nutrient deficiency
After three days with no food, your macronutrients will all be at basically zero. Your body will also be running out of vitamins and minerals, the micronutrients. If you eat a lot of healthy food, including lots of vegetables and fruits, you can start to recover quickly, but by the end of your fast, your body will begin to feel unpleasant.
Moodiness and irritability
You likely know what it feels like to be hangry. Imagine being hangry for more than three days straight. You can overcome that, but just be aware that it is very likely to happen.
Is a water fast or intermittent fasting better for weight loss?
Intermittent fasting is an umbrella term covering a lot of different types of diets. They all focus on eating no food, or little food, but only part of the time. Some intermittent fasting diets include fasting for part of the day (such as 16 hours), following severe calorie restrictions only some of the time (like two days a week), or fasting completely for a day at a time (like alternate-day fasting, where you fast completely every other day).
Various intermittent fasting methods have been shown to help people lose weight and reduce inflammation. One review finds that intermittent fasting can result in about the same amount of weight loss as calorie restriction does. A long water fast can result in weight loss, but there’s a more significant risk of bounceback weight. Overall, intermittent fasting is more likely to give you good results.
Frequently asked questions
Is fasting more than 72 hours bad?
Yes, fasting longer than 72 hours is not usually recommended. If you have done long fasts of up to 72 hours before and you feel confident, you can try it, but an 86-hour fast is not for beginners.
What is the most beneficial fasting length?
This depends on you and what you want. A 16-hour intermittent fast might be plenty for your weight loss goals, or you might fast for a day or two. Get used to shorter fasts before attempting longer ones.
What is the maximum number of days you should fast?
You shouldn’t fast for more than three days. Although you might lose weight, the overall effect on your health will be more negative than positive.
