Why did I write this article?

Many people got in contact asking if there was any truth in this BBC Trust Me, I’m a Doctor article. If there was they thought, then what good is any weight loss effort if our gut bacteria is the wrong type for the foods we are eating?

How is it relevant?

The human microbiota is a very new and exciting area of research with further research coming out all the time. However, it’s important to remain sceptical and put things into perspective when considering any new study in this area, especially when it comes to weight loss.

What is the take-home message?

There is no doubt that our microbiota is very important and we should do our best to look after it. However, blaming post-meal blood glucose level rises as the sole reason for an obesity epidemic is overly simplistic in my opinion.

While it is indeed interesting that people respond differently to different foods, what we should be asking ourselves is what is more likely? That we will lose weight by drinking coke, ice-cream and chocolate because they fit in with our gut bacteria make-up? Or that we stick to what science knows and use behaviour change based principles to achieve the principles of proper nutrition on a consistent basis? I think we know the answer.

Picture symbolising the close relationship between the human microbiome and the brain

Like I was, you may be surprised to hear that there are ten times more bacterial cells than human cells in the body. So technically we are more bacteria than we are human!

These can be found all over your body from your nose, mouth, genitals, skin and of course your gut, the latter of which may be analysed by taking a stool sample. We have so many that we are now able to see the human cloud of bacteria that engulfs us 24/7. We may even have our very own unique bacterial fingerprint.

Intuitively this sounds a little alarming, but like most things we are born with, they serve an intricate, vital purpose.

Some animal studies have also indicated some other exciting relationships between our gut bacteria and our weight, stress and mindset.

It’s important not to get too carried away with animal studies however as there are apparent vital differences between mice and humans. It’s also important to remember our that our gut bacteria is changing all the time based on our lifestyle habits (exercise, nutrition, sleep, stress and mindset).

If we want a snapshot of our gut bacteria, analysing our poo is a useful way to do so, and this is precisely what they did in a recent Trust Me, I’m a Doctor article published on the BBC.

During the show and the in the article they seemed to give the impression that by looking at our gut bacteria, we may be able to tailor our nutrition to foods which suit our bacteria. This in turn they postulated, would enable us to control our glucose response to foods and thus help us manage our weight more efficiently.

While this sounds exciting, in my humble opinion this approach is at best misguided and at worst extremely damaging to those who take home this message, namely hard-working, yet ultimately vulnerable individuals trying to lose weight across the UK. The problem with a purely biomedical approach such as this is that it becomes tempting to take the path that we merely need a simple pill/probiotic, superfood and tailored nutrition plan and all will be well.

This also provides an excellent example why you should not trust what someone says just because they are a doctor. This is called the appeal to authority fallacy. Now before you think I’m all pro-David Avocado Wolf and anti Doctors, this is not the case.

I’m merely trying to make a point that we should reserve adopting beliefs in any theory before it has been scrutinised by a healthy sceptical eye. For example, Dr Oz. is an intelligent man but uses his authority to make billions from vulnerable people in the states. Now I am not saying the BBC Doctors are similar to Dr Oz, just that In any new area of research such as this, we should be extra sceptical before concluding.

In my humble opinion the problems with the BBC article are as follows:

We have known for a long time now that different diets work for different people, which is why we take a science-based approach here at Health by Science by working with our clients to determine what their optimal nutrition is based on their lifestyle, preferences and outcome measures.

The one thing they all have in common, however, is that they adhere to the principles of proper nutrition, namely adequate protein, carb, veg and fat intake along with a healthy relationship with treats. To facilitate this, we utilise the science from behavioural psychology, behavioural economics, neuroscience and sociology.

Any health and disease-related topic should also take into account the psychological and sociological factors. It could be argued forcefully that the obesity epidemic we face is much more of a mental and sociological issue than a biomedical one. For example, very few people have a slow metabolism than we are led to believe, and weight loss pills are deadly.
an image of a quote highlighting the importance of consistent good quality nutrition.

Psychological factors

So many of our anxieties around diet come from our constant search for the search for the perfect diet plan or food that will finally get us the results we want. This food is a superfood! This food is bad! Eat this! Don’t eat that! We obsess about the ideas around certain foods but rarely take a moment to stop and build awareness about what we are consistently putting in our mouths and why.

Our idea of what constitutes proper nutrition has been skewed by years of contradictions, misinformation and bogus quick fix diets. On top of that, how we eat, how we approach food and our relationship with it plays a massive role.

There is a common fallacy among many who struggle to eat healthily and nutritionists that we are doomed by our biology to remain the same weight. The reality which is not often what we want to hear or the sexiest is that it’s tough to change habits. Especially when they have been reinforced over the years.

However with the right approach eating in line with the principles of proper nutrition is a surprisingly teachable skill for those willing to be taught.

There are four big things we would all benefit from learning to do:

  1. Discover our Meaning of proper nutrition, what do we believe adequate nutrition is? Why do we need to eat carbs, fats, protein and veggies? How much of each do you need? What does this look like in real food terms
  2. Build Awareness of what your behaviours right now, non-judgmentally, non-critically. By self-compassionately seeing things for what they are and not what we wish them to be we can begin to start changing our habits more efficiently.
  3. Learn to Prioritise good nutrition by realising how it affects the quality of our lives such as our body composition, health and performance. Once you understand how much better life is with good consistent nutrition, making better food choices and forming a better relationship with food becomes a want instead of a should.
  4. Create Strategies to maximise your chances of success. Plan, prepare, commit. Do you have a regular food shop each week? Do you follow structured mealtimes? Do you know how you’re likely to fail and plan accordingly?


Sociological factors

A few decades from now, the current laissez-faire attitudes to sugar (now present in 80% of supermarket foods), the poor nutrition options in canteens at work, the continuous cakes brought in to celebrate various occasions at work, the poor quality food outlet options around town, the inferior quality ingredients used by many restaurant outlets and the repeatedly irresponsible media coverage of nutrition research, may seem as reckless and strange as permitting cars without seatbelts or smoking on aeroplanes.

Food companies marketing spend billions of pounds every year to influence our buying decisions and if you think you are immune from those billboards or strategically arranged supermarket shelves, think again.

We all had biases and heuristics which make us more vulnerable to poor decision-making on a daily basis, especially when we’re tired and stressed (which just so happens to be when we reach for the well-deserved treat right?).

Having a healthy sceptical eye, a healthy relationship and understanding of food and a healthy environment with food can act like a lifejacket, protecting you from the worst excesses of the obesogenic world we now inhabit.

Changing the way you eat is far from simple, but nor, crucially, is it impossible. After all, as omnivores, we were not born knowing what to eat. We all had to learn it, every one of us, as children sitting expectantly, waiting to be fed.



The difference in individual diets may come more from a psychosocial and sociological perspective rather than a biological one. The principles of nutrition have remained mostly unchanged for the last few thousand years. The methods by which we achieve that varies from person to person because of the complex and varied world we live in.

While we are far from experts on the topic of immunology and the microbiota, as part of our science-based approach, the Health by Science team got hold of the research article referenced by BBC Trust Me I’m a Doctor, providing the evidence for the claims made on the show. You can take a look at our critical appraisal summary here in this little infographic.

Overall maybe looking at your poo is significant but the big question is whether or not it’s clinically significant, i.e. are there bigger fish to fry? In my humble opinion there definitely are.

If you can learn to achieve the principles of good nutrition with consistency, through a sustainable approach to behaviour change, your gut will thank you massively for it. This, in turn, will have a positive effect on your body composition and physical and mental health and performance in day to day life. Thus helping to maximise your quality of life.