Gut bacteria & fasting: meet the night crew - The Big IF Dailies
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In the past, every human on the planet fasted regularly. Not out of choice, I might add. Before agriculture, feeding ourselves involved effort and risk. Foraging came with a chance of becoming food for other animals, and hunting meant putting ourselves in real danger. Without ways to preserve our food, it would spoil quickly. We were on a never-ending mission to find the sustenance to survive. Today, things are different for many of us. We can get food with the swipe of a smartphone.

and eat when we want at all hours of the day. But at what cost to our bodies and the helpful microbes that live inside us? This is Zoe Science and Nutrition. I'm Jonathan Wall. Today on the show we ask, is fasting important for the health of our gut? This episode is part of a limited series to celebrate the launch of the Big If Study.

the world's biggest clinical study to discover how intermittent fasting really affects us. By inviting our amazing community of citizen scientists to take part in this experiment, we hope to understand whether intermittent fasting really can improve how we feel, from our hunger levels to our mood and energy.

To take part for free and discover if intermittent fasting can work for you, simply go to joinzoe.com slash thebigif. That's T-H-E-B-I-G-I-F or via the link in the show notes. When we were looking for someone to speak about what's happening in our gut when we fast, we didn't have to look very far.

In fact, one of the leaders in this field is someone I speak to most days and someone you likely know too. I'm Tim Spector. I've been studying the microbiome for 12 years now. I do research in this area. I have a medical background. And more importantly in Tim's estimations, when it comes to fasting... I've also tried it myself, so I've got some practical experience.

If you don't know Tim already, he's one of the world's most cited scientists. When it comes to what's going on inside our gut when we fast, Tim says a lot of this comes down to two different teams of bacteria that operate inside us. We've known for a while that when you fast, a different set of bacteria appear in your gut because bacteria replicate every hour or so. And when there's no food for them, suddenly the group that depend on food die away or go into a bit of a sleep

and others that live off the debris and the rubbish that's left behind come out of the woodwork and multiply. Each time you eat, the brain sends signals to the gut, mobilising an army of specialist microbes. Some get to work on fibre, some on fats. But others aren't interested in the food we eat. They have a taste for something a little more human.

One such microbe is named Acomancia munisfilia. Catchy name, I know. Well, these little critters love to chow down on our mucus. So when the food-loving microbes disappear, Acomancia comes out in force. And it then feeds off the surface of the gut, which is free of food and free of these other food-eating microbes. So it eats the sugars that are on the mucus layer of the gut. And it basically trims them down so that you get a nice smooth surface.

This then allows the gut layer to keep regenerating new cells. Having bacteria eating away at our bodies from the inside, it doesn't sound good. But Tim says it's not really that different to having a manicure. You know, we cut bits of our body off all the time, like our hair and our nails, and we're constantly shedding our skin. So our bodies are constantly repairing in ways we can't see.

This is a natural phenomenon. It's an essential part of our repair processes and keeping our immune system strong. That means that all the time, dead tissues are being removed and this allows all fresh tissues to work perfectly. We'll take Tim's word for it. So we need to give the nighttime microbes a chance to play, away from the greedy, calorie-hungry day crew.

But we know that starving ourselves is never a good idea. So what's the perfect timeframe between eating and fasting? Well, it turns out this is a question where scientists don't know the answer and one that Tim is excited to find out all about with your help from the Big If Study.

I'd like to know what's the optimum period of fasting for most people that is sustainable? How much of an interval between your last meal and your first meal? Can we tell which people are going to do better than others, which people find it really hard to do this, that might actually benefit from only a short fast, and which people might actually benefit from a really long fast?

As always, we know that one size doesn't fit all. It's important we don't fall into the same trap as we do for food, that we say, this is one fasting regime for everybody. So I'd love that we get a really sort of tailored fasting plan for everybody so that everyone can understand what works best for them. So there we have it. You have one set of bugs that love to chow down on your food. They're pretty wild and they don't half make a mess.

Then at night time, another crew comes to take out the trash. That's if you let them. This means giving them the environment they need to do their work. No food in the way for them, which means fasting for you. Some people who've made the shift to intermittent fasting report increased energy, elevated mood and even weight loss. So why not sign up to the Big If Study and see if it works for you.

The episode you just heard is part of a limited series to celebrate the launch of The Big If Study, the world's biggest clinical study to discover how intermittent fasting affects our mood, energy, and hunger. To take part for free and discover if intermittent fasting can work for you, simply go to joinzoe.com slash thebigif or via the link in the show notes.

This episode was produced by Fascinate Productions with support from Yellow Hewings Martin and Alex Jones at Zoe. Zoe Daly's come out each day between now and our next regular episode.