Key Topics Covered

Normally Netflix nutrition documentaries are terrible sources of information, however, we like to watch them to have greater awareness of the topics so that we can provide educated answers to our clients if they have questions. Today we will provide a balanced review of Hack Your Health: The Secrets of Your Gut, touching on both the positive and negative associations of this documentary.

Overview

• As a general perspective, the microbiome IS linked with many aspects of health and wellbeing. 
• There is an endless list of complex interactions between the gut and other aspects of health.
• There’s were multiple positive things they mentioned in the documentary about improving your gut health that we agree with. 
• We will split this review up into 3 sections: Positives, Interesting Points and Negatives. 

Positives: 

• They talked about how approximately 70% of our immune system lives in our gut, which has a large influence on immune function which is largely underappreciated.
• They highlighted how the microbiome is flexible and something we can change. 
• Encouraged microbiome diversity which we think is great advice.
• They also discussed how if we cut foods out we lose species of our gut bacteria and when we reintroduce those foods and fibres, it can cause symptoms. 
• It was mentioned that some people feel like they can ONLY eat 10-15 different types of foods and are trapped cycle in a cycle where every time they try to reintroduce stuff, it causes issues. Although, the answer would be to start low and go slow and allow the microbiome to adapt.
• They made a joke about micro-dosing potato chips at the start of reintroducing them for the person who had struggled with them previously. This is an approach that makes sense because if it’s microbiome-related, it helps. If it’s mental, it still helps. If it’s fat malabsorption, it can help in many cases too. 
• They also touched on differences such as how the Western world has less microbial diversity than the less industrialised world.

Interesting points:

• FDA in America recommends 28-40g of fibre per day. The average American eats 15g per day apparently.
• Scientists recommend >50g. 
• They had a semi-hot take: Not eating enough fibre leads to the microbes not having enough to eat, which leads to them eating the mucosal lining of the gut. Then microbes get through due to increased permeability. This is something that can cause inflammation and diseases like IBD and some types of IBS.
  • Our thoughts are that this is strong wording and potentially fear-mongering. But we do know lower fibre intake is linked with IBD to a degree.
  • The documentary makers also asked the question “Are we missing certain bacteria that are here to protect us?” in relation to developing conditions like IBS and IBD. This is a great question!
  •  I personally find that when you look at the research with fresh eyes it is hugely promising in relation to questions like that. 
  • But as of 2024 do we have evidence of this solving stuff like IBS and IBD?
  • Through a super simplified lens of saying “X person is lacking bifidobacteria, let’s solve this.” It has merit to a degree, but it’s hard to say how practical it is right now.

• They did microbiome testing,  but the lead researcher in the documentary did highlight “I don’t think it makes sense to do at this time” and also said “the positive steps we can do, we don’t need an analysis for. But if you want to know, go ahead, and for research it’s a great tool.”
• They mentioned how different people extract a different amount of calories and nutrients from food which is true. Although we would de-emphasise how much this matters for many cases.
• They referenced the mice study where there were two lean twins. The microbiome of an obese mouse was added to one twin. Both twins were in the same environment and provided the same food but the mice that were given an obese microbiome became obese. This study is compelling. But do we see that in humans? Are there any real controlled examples?

• They mentioned a couple of bacteria linked with “having a tougher time losing weight” or “increased hunger.” Then said, “it’s never as simple as one bacteria, because no bacteria acts alone.”
  •  Adding our two cents here, people who are obese on average do have different microbiomes than those who are lean. This creates a chicken or the egg scenario. Which one comes first and how do they influence and interact with each other?
  • Backtracking to the mice study, they made it out that the microbiome causes obesity. But it is a stretch to say that strongly.
  • Shouldn’t we all be trying to do things that are good for our microbiome and for our health?
• One of the researchers talked about the ‘ABC’s’ which means always be counting. Not calories. But plants. Aim for 20-30 per week.
  • Note that you would also tell somebody to aim for >20 different plants per week regardless of microbiome situation or testing. 
  • They placed a big emphasis on “BUT NOT CALORIES” which we believe is worth being aware of both variables rather than JUST focusing on one thing.

• They mentioned a ‘competitive eater’ and we were dreading that they were going to try to use the microbiome to explain why he wasn’t hungry when there are other things that could be influencing hunger.
• However, the person in charge did explain factors like the stomach being stretched and the brain’s influence which was good to see that they weren’t oversimplifying topics and hyper-focusing on the microbiome. 
• There was a bit of an excessive link between gut health and health outcomes. We know that it is super important but looking at it in isolation for stuff like obesity is a bit of a stretch. 
• We can unpack this by asking “do we have evidence for gut health leading to weight loss in isolation?”
• For example, it’s not like we are seeing probiotic and fibre supplementation in isolation leading to large weight losses in studies. 

Negatives:

• One line that annoyed us in the ‘obesity section’ that we can never let slide was “the population has been doing what we have recommended for many decades, yet the obesity epidemic has not slowed down or reversed.” It is such a stretch to say that the population in America or Australia follows the nutrition guidelines of their country.
• Another claim that was made was “your blood sugar 2hrs after a meal is directly related to weight loss or weight gain” and this is worth addressing. We’ve spoken a fair bit on the podcast about how this isn’t true. 

• Tim Spector was featured in this documentary and Zoe, a company he cofounded, has largely been working based on a lot of the principles mentioned in this documentary.
• In many cases they have taken them very far since they do microbiome testing and try to individualise food intake based on continuous blood glucose monitoring. They released a study late last year which I think is relevant here.
• That study had quite underwhelming results. The change in triglycerides was promoted, but the difference was still small.
• There was no significant difference in factors like insulin, glucose levels and blood pressure. The average total weight loss was 2% of body weight over 18 weeks.
• It’s hard to control for compliance and the people who stick to the plan get better results. But I think this is worth mentioning, particularly from the body composition perspective.
• Sometimes a documentary like this can give the impression that just looking at gut health will be the solution, but as always it is a bit of a multifactorial situation. The microbiome matters but so do many other factors.

Summary:

Somebody on Instagram sent through the following summary of the documentary that we liked which was:

“Eat a diverse range of fibre-filled foods to increase diversity in the gut microbiome. They tried to make links to diseases and conditions, where in some cases it seemed like there was less than solid evidence. As a summary though, prioritising whole foods has a positive impact on your microbiome and overall health.”

Relevant Blogs/Resources

Documentary:

Hack Your Health: The Secrets of Your Gut

Relevant Studies:

• Effects of a personalized nutrition program on cardiometabolic health: a randomized controlled trial | Nature Medicine