A mind-blowing simulation has shown what happens to your body when you fast for 36 hours.
Food is a vital part of our life, because while it can bring us a staggering amount of joy, it's also something that stands between life and death.
In the modern age, we seem to have found an infinite number of ways to package the things we need to sustain us.
With that, comes some food that probably does more harm than good - but at least it's fun.
Anyway, despite needing food to survive, there are actually some major benefits to going without for a sustained period of time.
Personally, I could never - but let's hear what the experts have to say.
Back in the day—way back—people weren’t scheduling intermittent fasts or measuring their macros. They simply ate when they could.
Dr Valter Longo, a longevity researcher at the University of Southern California, told NIH: “So, they were forced to fast.”
These days, though, food is just about everywhere—at least in much of the developed world. And that has drastically altered the way we eat.
“This has shifted our eating patterns,” said Dr Vicki Catenacci, a nutrition researcher at the University of Colorado. “People now eat, on average, throughout a 14-hour period each day.”
With food constantly available, our bodies rarely get a break from digestion—but fasting flips the switch on that.
So what exactly happens during a 36-hour fast?
- 4 Hours In: Your insulin levels start to dip, prompting your body to burn through stored sugar.
- 8 Hours: Blood sugar levels drop further, and your body switches to using glycogen for energy.
- 12 Hours: Fat burning officially kicks in, insulin levels fall even more, and you enter ketosis.
- 16 Hours: Autophagy begins—your body starts cleaning house by breaking down damaged cells and flushing out toxins.
- 24 Hours: Big cellular repair takes place, inflammation decreases, and your insulin sensitivity improves.
- 30 Hours: Growth hormone production spikes, which helps protect your muscle tissue and speeds up fat loss.
- 36 Hours: You hit peak autophagy. Dead cells are cleared, tissue regeneration kicks in, and your metabolism gets a full reset.
A viral simulation by YouTube channel Wellness Wise has given us a more detailed look at what happens:
Associate professor of nutrition at the University of Surrey, Adam Collins, told The Guardian: “Whether you can get those effects with just a 36-hour fast once a week, [I’m] not sure.”
He pointed out that a lot of the research we have is based on animal studies, mostly involving rodents.
James Betts, professor of metabolic physiology at the University of Bath, added: “There [are] a lot of proposed benefits to [running on fats]. But a lot of the research hasn’t really [been borne out in] human beings. So we don’t see dramatic health benefits, certainly in the short term.
“And you can tend to be a little physically inactive during the fast as well because you just don’t have the energy levels for that.”
And then there’s the issue of going too far. According to Johns Hopkins Medicine, pushing past a 24-hour fast might backfire.
They warn that "going too long without eating might actually encourage your body to start storing more fat in response to starvation."