Calories, Gut Bacteria & Fat Mice

July 25, 2022 315 Views
Calories, Gut Bacteria & Fat Mice

Of all the misleading information and untruths about nutrition, surely the greatest is the calorie myth. In truth, calorie counting is bad for your physical health, mental health and the planet.

This arbitrary numerical value has been the key driver to a deprivation mentality that at best makes us miss out on nutritious foods and at worst fuels disordered eating behaviour and poor mental health.  

So, let’s take apart the whole concept of calories in four easy steps….

Ban The Bomb

Firstly, the calorie content of food is calculated using a bomb calorimeter, a clever bit of equipment that takes a sample and completely burns it measuring the amount of heat that it produces. A few calculations later and you have that magic number that is printed on every food label and menu as dictated by current legislation. Sounds very scientific and standardised, which is probably why it has become an “accepted fact”. The issue is that the human body has a perfectly adapted and elegant system to digest, absorb and metabolise nutrients from a whole range of different foods….. it is not an internal combustion engine.

Nutrients Not Calories

Secondly, human beings are probably the most heterogenous species on the planet, but we are supposed to accept that every adult requires around 2000 calories each day? No accounting for metabolic rates? Body composition? Physical activity levels? Ethnicity? And worst of all, the idea that eating 2000 calories from any kind of food is ok??  As a nutritionist I am interested in soluble and insoluble fibre, vitamins, minerals, trace elements, antioxidants, essential fatty acids and omega 3 fatty acids and what effect they have on health. NEVER calories.

Surviving Famine

Thirdly, the concept of energy balance is also flawed. The idea that the only reason why bodyweight remains stable is because the number of calories going in (eating and drinking) equals the number of calories being expended (staying alive and moving about) is once again simplifying a much more complicated series of factors. The human body is built for survival and in doing so it will adjust metabolic rates, increase absorption and reduce excretion of nutrients to stay functioning. It doesn’t matter what your starting bodyweight is, if you mimic a famine by drastically reducing your food intake it will trigger it to go into survival mode.  I saw many examples of this when I was working as a NHS Dietitian; restricted tube-fed patients, morbidly obese serial dieters and babies with severe reflux (vomiting) all manging to maintain their bodyweight on a very limited dietary intake.

Calorie Counting is BAD

Calorie counting is also pointless because it doesn’t consider the gut microbiome and how much this influences energy metabolism within the body.  The gut microbiome is the term used to describe the collection of microorganisms (bacteria, yeasts and viruses) that colonise the entire length of our gastrointestinal tract. That’s roughly 100 trillion microorganisms in total and more than 160 species. The gut microbiome is hugely dynamic and the types of species that proliferate are affected by key factors, such as antibiotic use (prescribed and foods derived from intensively reared animals), dietary fibre, micronutrient deficiencies and artificial sweeteners. 

Fat Mice

To help illustrate my point let me tell you about an interesting experiment using standard weight, germ-free laboratory mice that are specially bred to have no gut microbiome. They were split into two groups and inoculated with faecal samples containing gut microorganisms from obese and non-obese people and then fed exactly the same amount and type of food. After a period of time the mice that were given the obese group sample became overweight whilst the weight of the mice given the non-obese group sample remained stable.  The findings would suggest that the type of microorganisms that live in your gut can significantly affect energy metabolism and fat deposition.

Calorie counting and listing calorie contents on food labels and restaurant menus is outdated and has had absolutely no impact on the obesity and environmental crisis.