Lose weight AND boost your brain

By Dr Clare Bailey with DR MICHAEL MOSLEY

WE LIKE to think that we are in charge of the decisions we make, from what we choose to eat to where we go on holiday.

But the truth is we make a lot of decisions subconsciously, guided by signals and cues that we are not even aware of.

Why did you eat that muffin on the way to work? Was it because you really, really wanted it, weighed up the benefits and the costs, and decided to buy it? Or did you see it when you went into the coffee shop and just picked it up on a whim? Most of us eat mindlessly, guided by habit and influenced by advertising.

But what about our gut bacteria? Is it plausible that tiny single- celled creatures lurking in our gut can also influence our decision-making?

We think so, and so do an increasing number of scientists. Our microbes have the opportunity, motive and tools to manipulate us.

We’ve talked before about the brain in your gut — the enteric system that contains the same number of neurons as you’ll find in the brain of a cat, which communicates with the brain in your head via the vagus nerve. The vagus nerve is like a telephone line. The enteric system talks to your brain and it talks back.

Now, there is plenty of evidence that your microbes can hack into this system and talk to your brain via the vagus nerve. They also produce hormones and neurotransmitters that can reach your brain via your bloodstream.

DOPAMINE, for example, is a ‘ feel- good hormone’. The microbes in your gut produce lots of it, possibly to reward you for doing what they want you to do (like eat more cake — see the sugar lovers below).

The microbes in your gut also produce chemicals that control your mood, like serotonin (another feel-good hormone) and GABA (a neurotransmitter that acts in a similar way to the antianxiety drug Valium). They even make chemicals that are similar to the main hunger hormones.

So microbes have the means to influence your brain. They also have the motive. Life in your gut is not for the faint-hearted. It is a state of endless war.

The microbes are not only competing for space and scarce resources, they also have different dietary demands. Some thrive on sugar, others love fat.

The more sugar you feed sugar eaters, the more they want. They are not like a friendly dog, waiting gratefully for anything that comes their way. They fight for life and will do anything to give themselves the edge.

Research from the Arizona State University Department of Psychology shows that microbes can not only influence how much we eat, but also what we eat.

We touched before on the idea that a diverse microbiome is associated with being slimmer and healthier, while a more limited ecosystem means you’re more likely to be overweight and sickly.

But it’s possible our microbes are doing more than just making us crave sugar. While a lot of this research has been carried out in animals rather than humans, we have no real reason to believe similar behaviours might not be seen in people, too.

Let’s give you an example. Mice, when infected by bacteria called

Toxoplasma gondii, become oddly reckless. Normally a mouse will stay in the shadows and avoid anything to do with cats. But when they are infected by Toxoplasma there’s a change of behaviour.

They are now attracted by cat urine and will deliberately move out into the open — to be killed.

The Toxoplasma bacteria are manipulating the mouse’s behaviour. They want it to be eaten by a cat, so that they can then infect the cat.

Scientists have also found that if you feed faeces from mice who display anxiety-like behaviour to mice who don’t display this behaviour, then those mice start to behave in a more anxious manner, too. This proves a relationship between what’s in the gut and the way creatures behave from an emotional perspective.

Research has also found it’s possible to make mice swim for longer, and more doggedly, if you feed them bacteria called L. rhamnosus. What’s more, they found that if you sever the vagus nerve in

these mice, so that the gut can no longer talk to the brain, the mice do not change their behaviour after being fed these bacteria, but instead swim as they’ve always swum before.

When it comes to humans, the evidence is more circumstantial. In a study involving 22 people, half chocoholics and the other half indifferent to chocolate, the researchers found those who loved chocolate had a different set of gut microbes from those who weren’t interested in the sweet stuff. This was despite the fact that both groups had been put on an identical diet for a set period of time before being tested.

There was also a double- blind, randomised, placebo- controlled trial (the gold standard for clinical trials) in which researchers showed that they could significantly improve depressed people’s moods by giving them a probiotic containing a mix of Lactobacillus acidophilus, Lactobacillus

casei and Bifidobacterium bifidum — all microbes found in a healthy gut.

And with infants, when the scientists examined their their nappies, children with colic (inconsolable crying) had reduced gut diversity and fewer bacteroidetes (the ‘good guys’) than those who didn’t cry as much.

One theory is lots of screaming means parents are more likely to pay attention to, fuss over and feed their babies, thereby providing the ‘ bad guy’ microbes — which are irritating the baby’s guts and causing it to scream — with more food. It turns into a vicious cycle, with miserable parents and an even more miserable baby the losers, and bad gut microbes the winners.

HOWEVER, you don’t have to be a colicky baby to struggle with sleep. Insomnia is a common problem, thought to affect one in three people in the UK, particularly the elderly.

But, intriguingly, a gut health-boosting diet can help here, too. A study published in the Journal of Clinical Sleep Medicine found that people who ate more fibre — something that’s a key part of the Clever Guts diet — tended to spend more time in deep sleep than those who ate less fibre.

It’s clear that a happy, healthy gut microbiome can lead to a happy, healthy you — but there’s also evidence to suggest that combining a Mediterranean style diet (which is what we’ve based the Clever Guts diet on) with intermittent fasting (the 5:2 approach) can actually boost brain function.

It could even help ward off degenerative diseases such as Alzheimer’s and Parkinson’s while also improving your memory and mood.

A review of 135 studies that looked at how the Mediterranean diet affects cognitive function long-term found that those who stuck to this sort of diet had less cognitive decline and better memory than those who didn’t.

Best of all, the research also suggested that you were never too old to benefit from switching to this diet.

Combine this with 5:2 and it looks like you’re setting your brain up for the best possible old age.

Why? Because cutting calories twice a week has been shown to not only improve neural connections in the brain, according to Professor Mark Mattson, a neuroscientist at the National Institute on Aging in the U.S. — it also seems to help protect the brain against dangerous proteins which build up in Alzheimer’s.

A delicious way of eating that helps you shed the pounds, improves sleep, puts you in a positive mood, and should get your body — and brain — in shape so you can carry on partying for many years to come might sound too good to be true.

But this isn’t a fad diet — these claims are backed by science. You might have decided to follow the plan for a few weeks just to get into your party dress, but we hope that once you’ve made it a part of your daily life and start to feel the difference, you’ll be hooked.