ZOE Science & Nutrition - How fasting affects energy and mood - The Big IF Dailies

Episode Date: October 26, 2022

Have you ever lost your temper because you were hungry? Feeling short-tempered when you’re overdue a bite to eat is an almost universal experience, with its own adjective - ‘hangry’. If missing just one meal turns you into a grump, you may think that fasting would turn you into the Incredible Hulk. However, new data suggests this might not be the case.  In this daily episode of ZOE Science & Nutrition, Dr Sarah Berry joins Jonathan to answer the question: how does fasting affect your energy and mood? This episode is part of a limited series to celebrate the launch of The Big IF Study: The world’s largest clinical study to discover how intermittent fasting affects our mood, energy and hunger levels. Want to know if intermittent fasting can work for you?  Take part for FREE: joinzoe.com/thebigif Download our FREE guide — Top 10 Tips to Live Healthier: https://zoe.com/freeguide This podcast was produced by Fascinate Productions.

You're in the restaurant and you've been waiting too long for your food. You're beginning to feel those hunger packs. The anger is bubbling. The next person who annoys you in even the most trivial way is about to get it. Don't worry, we've all been hangry. But if missing just one meal gets your blood boiling, surely skipping several will have you flipping tables, right? Maybe not. Could fasting for long periods of the day actually make you happier and more energetic?

This is Zoe Science and Nutrition. I'm Jonathan Wolf. Today on the show, we find out how food and fasting affects our energy and mood. My guest today is top nutritional scientist Sarah Berry. She spent a lot of her time studying how different people respond to food. From our Zoe Predicts studies, we've been able to look at the relationship between not just the food that we eat, but also how we eat. So things like fasting

and our energy, our alertness, and our mood. And we've been able to do this at a scale that's just never been done before, which is really exciting. She knows a thing or two about this topic then. Before we get into fasting specifics, let's start by finding out how food impacts our energy and mood. So we know that when you consume food, you have lots and lots of changes that occur in your circulation. And these range from increases in some of the components of the meal, such as the fat and the sugar and the protein. But also we know that they stimulate changes in a whole host of different hormones. And some of these hormones send feedback to our brain that impact lots of different signals in our brain that will affect factors such as our mood, such as our energy and our alertness. Got it. Bodily changes affect our brain. On to fasting then.

There are lots of different ways to fast. There's the time-restricted method where for example you might eat only during an eight-hour window and then fast for the other 16 hours. There's the 5-2 method where you severely restrict your calorie intake on two days each week and eat normally for the other five. Fasting is sometimes described as more sustainable than other diets, since most of the time we're told we don't have to change what we eat, only when. But if not eating for long periods of time is meant to make us feel better, what's happening when we feel hangry? This is often a downstream effect of just eating the wrong types of food.

So what we know from our own research and from other published research is if you consume highly processed foods or very refined carbohydrates, you get peaks in blood sugar, which also cause dips in blood sugar. And these dips in blood sugar that happen about two to four hours after consuming these kinds of meals can set off some quite unfavorable impacts on your brain. They can make you feel very irritable. They can make you feel agitated. It can increase your heart rate. And so sometimes people, I think, mistake that feeling four hours later as part of a negative impact of fasting, whereas actually it's a negative impact of a meal that they've eaten three to four hours before. Clearly what we eat is just as important as when. There's research showing at all

ages, particularly in children, but also in adolescents and adults, that if we can change from a very typical Western highly processed diet to more of a Mediterranean or minimally processed diet, you can actually have significant improvements in your mood as well as your energy levels. And these improvements in mood are seen in everything from irritability in children or poor behavior in children to changes in people that have anxiety or depression as adults. Ignoring the impact of what wheat for a second, some people think fasting alone is enough to improve your mood and energy levels. There's some interesting early evidence suggesting cognitive benefits as we age, and even that it could reduce symptoms of mental

health conditions like anxiety and depression. It may even boost your memory by increasing new brain cell production. And that's not all. There is some evidence emerging to show that people that do practice intermittent fasting, so they have a longer overnight fast period, might have improved energy levels, they might have improved sleep, and therefore they might also have improved mood. But this is something that hasn't been looked at at a population level in the way that we're going to be looking at in our study. What we know so far is that our energy and mood is affected by the quality of the food we eat. And being hangry isn't a normal hunger cue.

It's usually a symptom of a blood sugar roller coaster caused by eating foods that are not working well for your biology. We also know that some people report improved energy and improved sleep through fasting, which can lead to an improvement in mood. But as Sarah says, the whole topic of intermittent fasting is understudied and the jury's still out on a lot of it, which is why we're so excited about the Big If study. We'll finally be able to show whether intermittent fasting really can improve your mood and your energy. 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 the big if, 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 Dailies come out each day between now and our next regular episode.