Ep.3 Intermittent fasting for IBS – When you should eat
4 Jun, 2023

Episode Intro

What happens if you skip a meal or eat late at night? What does that do to your IBS? Should you do intermittent fasting? If you've got IBS in this episode, I'll give you some tips on when to eat as well as information on how the timings of your meals affects digestion. If you want to avoid gas and bloating at night, then this episode is for you. What if changing when you eat was part of the puzzle in resolving your bloating and erratic bowel habits?

Podcast transcript

Eating too often or not eating enough is actually a common theme when I look at my client’s diet diaries.

I normally give people feedback on whether they’re eating enough like protein, fats, fibre, as well as if there’s any like clear nutritional gaps in calcium, iron, or other key nutrients.

Something people don’t generally expect feedback on as much is the gaps between their meals. Now, the reason this is really important in our digestion is not only can we get really hungry if we don’t eat regularly, but it can also sometimes influence what it is we’re actually eating.

And what I mean by that is that sometimes if you are really hungry you tend to crave quick release energy foods, which might not be your optimal nutrition choices.

Introducing your migraing motor complex

But one of the biggest reasons for getting our eating pattern right is something called the migrating motor complex. If you haven’t heard of this before, don’t worry.

I’m going to explain what it is. You can think about it like your internal housekeeper. It’s a little impulse that moves through your small intestine, just keeping it clean and healthy. It’s like a small housekeeper sweeping away bacterial overgrowth, debris, like bits of old food and dead cells we no longer need.

And it just really helps to keep the insides of our intestines clean. It happens when we haven’t eaten for around an hour and a half, 90 minute. And this little cleaning process takes around one and a half to three hours. So it’s basically starting at the top of your small intestine and moving all the way through down to the bottom of the small intestine where it meets your large intestine.

Now it’s mostly within your stomach and the the upper part of your digestive system. And it only works when you haven’t eaten for about 90 minutes. So when your stomach is relatively empty. As soon as you start releasing those digestive hormones, then the process is gonna stop.

Is fasting good for IBS?

So this is getting into one of the first of my recommendations in that is you have an overnight fast of around 12 hours.

Now that might sound a little bit scary if you have never done fasting before and you think, “oh, I hate being hungry”. But because you’re doing this overnight, all it basically means is not eating after dinner.

If you were to have your dinner around seven o’clock at night, it’s just not eating again until seven o’clock the next morning. 12 hours should be possible for most people.

Although of course, because this is a generalized advice podcast, I can’t give you personal advice. And so it maybe that for you, it’s not possible to go for 12 hours without eating. Maybe you need to take medication at certain times and you need to have food in your stomach, or perhaps you have diabetes and you have to eat at regular intervals.

But for everyone else, you should be able to do this relatively easily.

Overnight fast for IBS

All you need to do is stop eating after you’ve finished your last meal of the day. And you can have water, you can have herb tea, but just nothing else with any energy in it. So no milky drinks or any other snacks. Now, if you are hungry, I do suggest eating. Don’t starve yourself and don’t feel hungry unnecessarily. However, sometimes we’re just eating out of habit or because you’re a bit bored or because it’s a routine and you don’t actually need the food.

So this is one of those cases where you obviously need to put this into practice for yourself and your own life and what makes sense for you. But the majority of people should be able to manage 12 hours without food.

Meal spacing can help IBS

Now the other thing is you can do is during the day is just to space your meals out, and I really advise people to try and get three main meals a day.

This basically means not grazing, not nibbling on food, all between meals.

And if you do need a snack, just have one specific snack and then stop until your lunch, for example, mid-morning. Or maybe you want to have an afternoon snack, but try not to nibble on food all throughout the day.

Whilst I’ve really focused on trying not to eat too much, I also want to really stress the importance of not fasting too much either.

Does fasting improve IBS?

In the case of IBS, there isn’t actually much evidence that fasting will improve your symptoms. Of course, you may find that not eating for certain periods of time helps your stomach feel better, but longer term, we really need to make sure we’re focusing on getting enough nutrients in enough. Things like iron and calcium and protein, and it’s really hard to do that if you’re not eating regular meals.

Different types of fasting

When I talk about fasting, I’m talking about three different types of fasting really.

1. 24 hour fasts

So there’s a long fast where people will go without food for up to two or three days. I definitely do not recommend that to the majority of people. That’s incredibly hard to sustain and can actually be quite dangerous.

Then sometimes people will do alternate day fasting, and actually a lot of the studies are done on alternate day fasting. Again, it’s really difficult to manage not eating for that amount of time, and very difficult to make sure that you’re properly nourished during the times when you do eat. So again, not really something I would recommend to majority of people.

2. 5:2 diet

The other types of fasting is like the 5:2 diet where you just eat a small amount of calories for two days a week, and the other five days a week you eat a normal amount of food. Again, just by cutting down your energy intakes, sometimes you can reduce your gut symptoms, and this is very much dependent on the types of foods that you might react to.

But we have to think about the long term. If you do this, are you going to be getting enough goodness. Are you gonna be getting enough food to keep you going and to make sure that you are not losing muscle mass. Or you are not nutrient deficient.

3. Time restricted feeding / restricted eating window

And then the third type of eating is really like time-restricted eating or time-restricted feeding.

And that’s a little bit what I was mentioning around a restricted window where you don’t eat for 12 hours But a lot of the research in terms of the benefits of doing this are based on an. Eight hour eating window and a 16 hour period for fasting. That in itself is quite a long time and you will struggle to fit in three good meals a day in eight hours because there’s not much time you’ve gotta cook and wash up and like do all your other work as well within that eight hours.

And it can just be quite time consuming for some people to eat enough in eight hours. And also you get hunger problems when you are not eating for 16 hours. But some people do find that works really well. Other types of like restriction that people commonly do is just skipping breakfast.

Instead of sort of actively saying, right, I’m going to eat three meals a day in a shorter amount of time, I just won’t bother having breakfast and won’t eat. And this can work well for some people, but there isn’t actually much evidence for fasting within IBS.

Research into fasting for IBS

There was one study from years and years ago where they starved about 36 people for seven days.

This was under very controlled studies, so don’t try this at home. Then they refed them and in this group of people, seven out of eight felt better in terms of things like their abdominal pain, bloating, diarrhea, nausea and things like that. And then in the control group who just had some medication and psychotherapy, only three out of 10 felt better out of those.

And again, it was fairly small. About 22 people. What we don’t know, however, is that what happened when they started eating normally again. And so, yes, you can feel better if you don’t eat. But at the same time we have to eat, we have to keep going. So it’s impossible to just go and not eat anything, and hope you feel better.

FODMAP stacking can increase your symptoms

Now, skipping meals. One of the reasons why skipping meals is not good is because then when you do eat, you need to get in enough protein and fiber and your ‘five a day’, (fruits and vegetables).

What that can lead to is FODMAP stacking. Now if you haven’t heard of the FODMAP diet before, it’s an acronym.

It stands for Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. And these are basically just certain types of carbohydrate that either rapidly ferment in the large intestine or they draw water into the small bowel and they can cause bloating or they can just cause fermentation by bacteria.

Now these are, sounds bad, but they’re in really common healthy foods like apples and chickpeas. Um, milk, avocados, mushrooms, like lot of. Common healthy vegetables and fruits that we want to eat a lot of, but actually in people who have IBS can cause some of the key issues. So FODMAP stacking just means when you are having a lot of those kind of foods in a certain meal.

Now that would be because you are trying to cram more food into a shorter amount of time, which is one of the reasons I don’t recommend going for this extended time-restricted eating window when you are only trying to eat in eight hours if you are trying to get three meals in.

Firstly, it’s not leaving much time in between the meals, so you might not be as hungry.

And this is why partly some people use it for weight loss. But this is one of the reasons why I don’t recommend it for IBS.

Fasting with constipation type IBS

The other thing is in IBS, sometimes when you have hunger pangs, you can then start to get digestive issues. Some people actually feel worse when they’re hungry. Almost like the hunger pangs kick off a session of bloating. And then that’s really the start of one of your flareups.

Obviously your cells in your digestive system that are releasing your hunger hormones can be part of your IBS presentation.

And what I have not differentiated so far in this episode is that of course your particular type of IBS may be very different from somebody else’s.

Saying what works for one person won’t always work for somebody else. You might have more of a constipation predominant type IBS, in which case regular eating is even more important. 

When you cut down on your meals you are reducing the gastrocolic reflex. That is one thing that stimulates a bowel movement. So when we eat, our stomach tells the rest of the body that there’s food coming in and it tries to make room by trying to encourage you to go and sit on the toilet.

And if you are only eating twice a day, you are missing one of the opportunities to get that moving.

And it’s particularly strong in the morning, which is really why I suggest eating first thing in the morning if you have constipation.

Which a lot of people I work with really don’t, because when you’ve got really bad constipation, often you can feel quite sick and nauseous in the morning, and I do understand that.

But you can train your body to receive food, and I will teach you a little bit more about how to do that in another episode.

Eating with your body clock – chrono-nutrition

Final point around the timing of when you eat is really gonna be about our circadian rhythm. This is our wake sleep cycle, but also every cell in our body has its own little clock.

The main clock, the super clock in our brain, that is the one that controls when most of our processes should happen. It sends out messages to every cell in the body telling us whether we’re in day or night.

And the brain also receive cues from the things that we do. When we are exposed to light from the sun, when we eat, when we move our body.

These are cues like behavioural things that we do. Our body is receiving information about where we are in time, whether we are in the daytime or the night-time. 

Chrononutrition for IBS

So one of the things that we do know, and this is a relatively newish area of research in terms of biology. It’s called chrono-nutrition. It’s about how when we eat at different times of the day that can also have an impact on how we digest the food and our metabolic state. We know that, for example, cells throughout the digestive system, including our liver, stomach, our intestines, they all work better during the day.

We also know that if you eat late at night, you are much less likely to be able to break down particularly fatty foods and they have a worse impact on your blood sugar level as well. And what I mean by that is that you are more insulin resistant in the night.

Blood sugar responses change throughout the day

If you are sitting eating after dinner, like you’re snacking on sugary or fatty foods.

And let’s face it, most snack foods are generally the foods that are higher in salt and fat and you know, tasty sugar. And those are normally the foods that we tend to wanna snack on. So it’s crisps and chocolate and things like that. We are less able to digest them and to, minimize the impact of those on our body when we eat at night.

The impact of eating late at night is that you may find things like reflux are worse. You can also increase bloating and problems with waking up in the night because you are still processing your food and it can like leave your body feeling a little bit hotter. So then you wake up a bit more. Then the next day you might be more tired.

Aim for 3 hours before bed after your last meal

So really wanna stress the benefit to leaving a gap between your dinner and going to bed. And this is why I say, you know, it’s not possible for everybody, but if you could try and eat your meal around seven o’clock at night, have around three hours gap, and then sort of think about, you know, going off to bed between 10 and 11. That’s giving yourself opportunity to sleep for eight hours.

But it’s also given your body opportunity to let you digest your food before you go and lie down for eight hours.

In summary

To summarize this little episode, my main advice for people who have IBS around timing of food is

  • aim for three meals a day.
  • Aim to eat at regular times each day. Try to stick to the same times if you can.
  • Try to have three hours roughly before going to bed after your main meal
  • and don’t snack all day.

But if you do get really hungry, eat like it’s okay to break these. These are guidelines, they’re not rules. And so if on a certain day you know, you eat your dinner at nine o’clock cuz you’ve gone out for dinner with friends or you skip breakfast because your car breakdown or something like it’s not the end of the world.

What’s more important is about setting a regular routine for your body and for your digestion. And then when you are in a good place, it’s okay to, you know, break your own guidelines. These aren’t rules.

They’re things that you put in place.

These would be my generic bits of advice. Now, these don’t work for everybody, and so you might find this isn’t going to work for you, but without knowing your particular case, I can’t give you personalized advice.

I just think these are generic things that most people would do well to think about if they have IBS.

These are some basic things that I like to start with with my clients because it’s free. It’s not gonna cost you anything to change your eating times and just to try and think about eating routines. So I hope that’s helpful and I will see you on the next episode next week.

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