What if double Olympic gold medallist, James Cracknell, Entrepreneur & Primal Living founder, Steve Bennett, along with two doctors, one nurse & PhD Nutritionist, could run four marathons over 5 days all without consuming any food? What would it mean to metabolic science?

Team Press Release and all data to follow shortly - please subscribe to Primal Living on YouTube.

In his own account, Steve Bennett shares his experience on the Zero Calories - 5 Days - 100 Miles Challenge with us all....


As a health experiment with medical testing before, during and after, we want to see how metabolic flexibility can truly work.

The hypothesis is that when you are already fat adapted and stop any incoming food, then your body will still continue to run by burning its own body fat as fuel. It would indicate whether fasting is safe and even beneficial while putting the body under stress (like running and walking 100 miles)! 

The Concept

Doctor Ian Lake (who is a person with Type 1 Diabetes) believes that the current advise and lack of hope given to patients is not all it could be. After searching for evidence on what is doable while fasting, he found that no such experiment had taken place before and decided to assemble a diverse team of individuals to join him on a experiment to cover 100 miles over five days while consuming zero calories.  

Ian Lake assembled a mixed sex team between the ages of 29 to 62. Two people had type 1 diabetes, one was obese, one was a professional athlete, one a nutritionist, one an Eating Disorder specialist, one a nurse and finally, one a health author who was previously obese - that's me!

Building Out The Concept

My involvement came about when Dr Ian Lake approached me to both sponsor the event and to take part in it. 0-5-100 was due to initially take part early in May, with all participants finishing the event by walking on stage at the Public Health Collaboration Conference. Sadly, neither event could physically take place due to Covid-19 and as a result, the event was restaged for September this year.

I happily sponsored the hotels along route and hired a filming crew to document the experiment from start to finish. Ian secured support from medical manufacturers to monitor bloods, cortisol levels and breath analysis.

The Team

James Cracknell - Olympic Gold Medallist

Myself, Steve Bennett - Health Author & Previously Obese

Dr Ian Lake - GP & Type 1 Diabetic

Jake Thompson - Obese

Jon Furniss = Type 1 Diabetic

Dr Ali Ibrahim - Consultant Psychiatrist  Specialising in Paediatric Eating Disorders

Gayle Garry - Nurse & Diabetes Specialist

Dr Trudi Deakin - Dietitian

The Details

The team set off from Henley-on-Thames on the 19th of September, with Bristol as the final destination on the 23rd. Due to social distancing rules, the team travelled in pairs, but still social distanced. James Cracknell and Jon Furniss ran the event, Ian Lake and Ali Ibrahim equally ran and walked the event, and myself, Jake Thompson, Gayle Gerry and Trudi Deakin predominantly walked it.

We all ate our last meal on the Friday afternoon (8th September) and from that  point onwards, nobody consumed a single calorie. Just water, electrolytes, multivitamins and the odd coffee for some - black, of course. That was it! Zero calories!

For analysis (and to ensure nobody cheated), all participants were fitted with a Medtrum Continuous Glucose Monitor (to continually monitor blood glucose levels) and daily, both before and after the run/hike, measured with a finger prick test using a KetoMojo machine, both ketones and a further test of blood glucose levels were taken. Periodically, we also measured lactic acid.

Each morning before we departed we measured our cortisol levels via a saliva test and sent them off to a lab for analysis (which we are still awaiting the data for). Also, before setting out each day, Metabolic Solutions expert, Peter, connected us to their ECAL machine. This is an Indirect Calorimeter (more to follow on this once the data has been analysed and professionally reviewed). 

The Results

Moving forward, I am going to publish my results in 3 stages:

Stage 1  - The data I already have is in this report.

Stage 2 – The data from the Indirect Calorimeter and the Cortisol test - which I am still waiting on.

Stage 3 – Once we collate everything from all 8 participants, we will publish that too.

We also filmed and documented the entire experiment with three cameramen and a drone. Expect to see a full length feature on YouTube within a month or two. To subscribe so you don't miss it, please click here.

Steve Bennett's Zero Calories, 5 Days, 100 Miles Challenge Results

Here are my results, day by day (still some more to follow so please do subscribe). 

To stay up to date on my journey and the results, please follow me on Twitter.