“I wish there was just a pill I could take that would fix this?”
This is a phrase I’ve heard many times in my clinic when working with patients with gut issues – whether it be chronic constipation, constant loose stools, horrendous heartburn, bloating, gas, or a combination of some or all of the above.
Sadly, there is no magic pill. But what I’m seeing in clinical practice, is that the timing of WHEN we eat, can lead to significant improvements in symptoms, better than any fancy pill or potion in my experience.
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Many of my patients have been living with digestive problems for decades before we meet – 5, 10, 20, even 40 years is not uncommon. Although gut health is finally becoming a cool topic – for which I’m most happy – the Instagram pictures of fermented foods, and multi-ingredient colourful dishes hide the reality of suffering. Many gut patients tell me their guts "rule my life" - whether diagnosed with irritable bowel syndrome (IBS), an autoimmune disorder such as ulcerative colitis, or inflammatory condition of the bowel such as diverticulitis.

The reality of gut issues can mean sharing an office or a bed or going on a date is excruciatingly embarrassing and terrifying (you suddenly find you look six months pregnant JUST as you about to fit into a tight dress). I used to think this analogy was just a turn of speech, till patients started sending me pictures to prove it!

Gut issues can range from nightly heartburn, to the other end of the spectrum - sometimes not making it to the loo on time. Fecal incontinence as it is called, can be devastating – and lead to isolation and reclusion. Having constipation for a fortnight, the famous “vacation constipation” ruins whole holidays according to many I have met.

These scenarios can affect anybody. Behind the glamorous or calm exterior of friends and colleagues you may know, there can be horrendous suffering behind.

In this article I’m going to explain some of the common approaches to gut issues, and then come on to share my experience of using intermittent fasting, or time restricted eating (TRE) in my clinic. It is proving to be a simple, and do-able solution for many people with life-changing social and emotional consequences.


What you may have tried already

We now know that the kilo and a half (three pounds or so) of bacteria that lives principally in our colon – the last chamber of the digestive system before the exit – can have a big impact on our digestive health.

When this bacteria, dubbed the microbiome, has lots of diversity of different bugs, and particular ones are blooming happily away (such as the lactobacilli and the bifidobacteria), we tend to be in good gut health.

The landscape of our gut bacteria when in balance usually means our digestion works fine. No heartburn, no abdominal pain, no constipation, no chronic loose stools, no bloating, no gas.

People often ask me, how do I know if I’m in good gut health? You’ll know because gut health won’t even be on your radar! When it’s all working fine, you don’t even notice the machinations of it.

We now know that eating fermented foods with probiotic bacteria, and a wide range of different types of fibre and colour from plants such as vegetables, herbs, and fruit promotes a diverse range of bacteria in the gut, and therefore digestive health.
Some people use a low Fodmap diet (fermentable oligo-, di-, mono-saccharides and polyols) diet and exclude many plants from the diet that contain these fibres and sugars. Most gut patients to my clinic have already at some point tried this diet and this is what they report:
They often see short term improvements, but long-term, bigger deteriorations of their symptoms. This may be because the microbiome becomes fibre-starved, and diversity of bacteria diminish, and this has a knock-on impact on symptoms.

Many have also already tried super-dooper top of the range probiotic pills – which work well initially, but can stop working after a while. This may be because the microbiome likes lots of variety, so giving them the same 5, 10, 15, or 30 in a probiotic pill is like feeding someone their favourite food non-stop till they get sick of it and can’t take any more.
More research is needed in this area. This is simply the feedback from patients I have been getting.


Why the timing of when we eat may be crucial

I first started working with timings of eating with patients around 2014 when I saw the time restricted eating mice studies coming out of the renowned Salk Institue in California (see below).

Mice were divided into three camps over four months. They all had same access to exactly the same calorie count of food. One group could eat whenever they wanted around the 24-hour clock, one group could eat in a 12-hour window, and one could eat in an 8-hour window.

This article will focus on digestive health, but as an aside, can you guess which group of mice lost the most weight?

The ones eating little and often? Or the ones eating in the windows of time?

The ones eating “ad libitum” whenever they wanted, became obese. Surprising hey? This is why despite my training, I stopped advocating little and often diets at this point. The ones eating in the restricted windows LOST weight. Same calorie count, so quite a shocking study at the time that simply adjusting the timings of eating had such a big impact on weight.

Anyway, let’s get back to gut health. The mice eating all the time developed dysbiosis – their microbiomes became out of balance and low in good types of bacteria and didn’t have lots of different types.

However, the mice eating in the windows, grew healthy microbiomes – the longer the fasts eg between 12-16 hours stimulated healthier microbiomes. Lots of different types of bacteria proliferated and grew in their colons, and friendly types flourished. Remember you need lots of variety and friendly types to promote good gut health.

Many people turn to probiotic pills and potions to try to get this type of landscape in the gut (well for a short time anyway). But the 2014 studies (see below), indicated that timing of eating may be the long-term most powerful and practical solution - if humans would respond similarly to the mice.

Seeing a better microbiome (which can promote gut health) by doing NOTHING, ie fasting for a long stretch at some point in the 24-hour cycle is a pretty interesting result.

I started to see results in the humans I was working with quite quickly.

So what is happening? It appears that if you eat your food all during the daytime, then have a nice long stretch overnight (in the case of humans) with no food, or work for your digestive system to do, the microbiome regenerates. I see the improvements to diversity of the microbiome and flourishing of friendly species on stool samples some patients do before and after we work together.

I often tell my patients that NOT eating overnight for a long stretch (eg 12-16 hours) is like keeping off the grass of a lawn you are trying to give a chance to grow.

If you’ve ever grown a lawn you’ll know what I mean. You need people NOT to walk on it so it can regenerate, sprout and flourish.

A healthy microbiome produces a fuel which helps mend the gut lining itself. This means that physically the health of the gut lining can improve through regular overnight fasts. If you remember the gut lining from your biology classes, the inside of our intestines are full of little tufts which literally look like tufts of grass which are used to increase surface area to absorb food. So think about it, fasting overnight for a stretch, could literally let your inner grass grow back, which could mean less inflammation of the gut lining and better absorption of food for your health. This is especially important in cases such as inflammatory bowel disorder where the gut lining is injured.

​Regeneration – from microbiome, to brain, heart, and skin, is now known as autophagy and is an exciting area of research. Autophagy is promoted in the body when we fast. Old cells are slung out, and new ones grow.

Many patients find that their digestive symptoms are much better if they focus their eating during the day time, and avoid eating at least 2-3 hour before bed. This makes sense from a physiological point of view. The digestive system we are learning is primed to work at top performance during the day, producing saliva, chemical scissor enzymes to break down food, produce insulin to handle sugar, and peristalsis the contractions that move food along the tract, during day light. So shifting your main meal to lunch rather than dinner may help reduce the chance of heart burn, bloating, and wind.

How to get the benefits of time restricted eating (or intermittent fasting as it is also called).

In my book The Gut Makeover which was first published in December 2015, I advocated a 12-hour overnight fast and many people have raved about the benefits to their digestive system of practicing this. It’s simply a matter of looking at your watch and noting what time you had your last mouthful of food in the evening, and not eating anything again till 12 hours later.


12:12

For example, if you finish dinner at 8pm, you don’t start breakfast till 8am.

When I work with patients I often stipulate only water or non-fructose herbal teas during the fasting period overnight.

Some people have adopted this research into daily practice and drink black coffee, but it depends on each individual if this is helpful or not. Black coffee is a powerful laxative for some people, so if loose stools is an issue in your particular case, this wouldn’t be right for you. However, if you have chronic constipation, it might be helpful during your fasting window. More research is needed in this area.

14:10

This means eating in a ten-hour window and fasting for 14 hours overnight.
My patients have generally found eating earlier is the best way to handle this.
For example, some professionals I see, who are very much still at work at 6pm, are having a more substantial lunch, then a light supper at work around 6pm. It means they no longer eat when they get home at 8, 9, or 10pm.
Next meal is 8am breakfast the next day.

16:8

This one really seems to suit people who have no appetite for breakfast, so can be easy for them.
You simply skip breakfast each day, and eat all your meals in an 8-hour window.
For example, some people like to eat between 11am and have their last mouthful of food by 7pm. Some like to just eat two substantial meals in the window, others three smaller meals. The great thing about time restricted eating is you are the boss and set your pattern. The potential trap with an 8-hour window is opening it too late in the day, and then finding yourself eating late at night which isn’t good for the digestive system at all. Front-loading your calories if you can into earlier in the day when they are easier to digest is more important than having a longer arduous fast.


Results

For people who have had IBS for years – and I mean sometimes decades – time restricted eating has been the turning point in their symptoms.

Each patient I work with, we try different patterns of timings, depending on their work, family, hunger patterns, lifestyle.

What we are seeing is practicing the window-eating strictly for at least one month sees a shift in many IBS or gut symptoms.

​With autoimmune gut disorders the 16:8 can lead to a lot of progress in symptoms, in my experience, in the first 4-6 weeks. Usually people switch to 14:10 after this. 16:8 is a short intervention in my view, and isn't generally practical longer term for many people. It can also be challenging getting all your nutrition into an 8-hour window, so again this is another reason to drop to 14:10 after the first month.. Remember fasting longer isn’t always better, and some people can become fatigued and depleted if they do this for too long. More important is making sure you eat earlier in the day, and wrap up eating 2-3 hours before bed latest.

Some people tell me when we meet they are already doing 12:12 or 14:10, but when we drill down to the detail of their lives, we find they aren’t – they are an hour or so out many days of the week.

It’s this tweaking to get the window-eating right that can make a big difference.

So 16:8 and 14:10 patients often have significant improvement in gut symptoms in one month, and then if they keep the 14:10 going for three or four, symptoms can be pretty much resolved in some cases. For maintenance some people keep 14:10 going for the long term five days a week, and drop to 12:12 two days a week.

Imagine if just getting the timing fine-tuned of your meals means that horrible heartburn you have been living with like background noise disappears. Or the dashing to the loo, bloating, and embarrassing gas is gone. Your vacation constipation no longer ruins every holiday.

What we’re learning is that the devil is in the detail with time restricted eating.

And remember: keep off the grass!



Chaix, A., Zarrinpar, A., Miu, P., Panda, S. (2014). Time-restricted feeding is a preventative and therapeutic intervention against diverse nutritional challenges. Cell Metabolism. http://dx.doi.org/10.1016/j.cmet.2014.11.001

Zarrinpar, A., Chaix, A., Yooseph, S., Panda, S. (2014). Diet and feeding pattern affect the diurnal dynamics of the gut microbiome. Cell Metabolism. http://dx.doi.org/10.1016/j.cmet.2014.11.008