Our metabolic system is remarkably flexible in its ability to use a variety of dietary macronutrients as fuels. Traditionally, carbohydrate-focussed diets have been recommended for participation in sports and carbohydrate loading prior to competitive events has been the main nutritional strategy for improved performance on the day.

However, in recent years, this strategy has been questioned and there are many research projects that have been undertaken to find whether high fat/low carb diets or high carb/low fat diets are best for endurance athletes. You may ask, why do we want to know? The human body has a very limited capacity to store carbohydrate – approximately 5g of glucose in circulation and between 100g-500g of glycogen in muscle. That’s enough fuel to keep us running/cycling/swimming for one and a half hours. That’s why we have to focus on getting carbs in on a regular basis via food, gels, drinks etc. during long course events such as marathons and iron man competitions. On the other hand, a person of average weight has around 10kgs of fat on their body – enough fuel to allow them to complete 30 plus marathons. It would make sense that we would want to access this big pool of unlimited energy in endurance sports.

There is always much debate amongst sports dieticians, nutritionists, physiologists etc. about what diet is best for each sport, but I work quite differently to that. I don’t agree with a sport approach, but more on an individual approach. For every research experiment where an athlete has done better on a high carb approach, there is another who did better on a high fat approach. Setting one dietary regime for an entire sport is discounting us all and our individual needs. Genetics, body type, training routine, metabolic health, blood sugar response, gut health etc all have a major part in the way we metabolise food so how could one size fits all?

When working with endurance athletes, fat adaptation is a factor that is always at the forefront of performance management. Symptoms such as constantly being hangry, getting hungry an hour after eating, feeling dizzy and completely exhausted after training etc. can suggest blood sugar imbalances and insufficient fuelling during training. Often, when these symptoms occur, an athlete will up the carbs and gels to offset, which can often make things worse. When we eat a lot of carbohydrates, our body responds with insulin, which clears glucose from the blood. If carb intake is too high, insulin can be magnified a few times and you actually end up hypoglycemic as it clears too much glucose from the blood. If this happens a few times a day and you are constantly carb loading, you may end up with a condition called insulin resistance, whereby the cells become numb to the action of insulin, and glucose can’t get into the cells. In the meantime, you have a big pool of energy in your fat stores that is largely being ignored.


As well as noting symptoms, I also use ECAL metabolic testing to assess how fat adapted the athletes I work with are. When we burn fat, we don’t sweat it out, we breathe it out. By analysing our breath after a 4 hour fast, the ECAL machine can inform us if we are burning fat or glucose. Ideally, we should be burning 80% fat for energy at this point. If the test shows that we are constantly looking for glucose then we know that dietary changes are required such as periodisation of low carb diets, then high carb diets, reducing the carbohydrate load in the diet on an ongoing basis, doing some training sessions fasted etc. Some athletes perform better on high fat, low carb diets but I like to use the phrase carbohydrate appropriate diet whereby carbs are in the diet but they are amazing, high fibre carbs and will help to keep blood sugar balanced, and our fat stores are still on the radar.

The fuelling we put in our mouth is important for sports performance but so is the fuel we have stored on our body. Being able to access that fuel at the appropriate time may provide the winning edge.


Fiona is one of my all time favourite people. After high school, I weighed in at 99kg. At 174cm, I have been overweight by 15-20 kgs for all my adult life. Until, at age 53, I met Fiona. She immediately diagnosed my primary problem and by following her dietary coaching, I lost 16 kgs in 5 months. More importantly, I have maintained this for more than a year now. Now, well into the second half of my life, life is good, very good. As I said, Fiona will always be one of my all time favourite people. Thank you Fiona.

Fiona ran a course at work and it was fantastic – I learned so much and she tailored the programs to each individual which worked really well. I reached my weight loss and health goals and it really wasn’t too hard and I still have treats!  More importantly, I feel much better in myself for making food changes and continued to see her independently when the course at work finished.
Charlotte Carlish
Indigestion, stomach pain and abdominal cramps, were an every day occurrence for me. I was quite desperate by the time I found Fiona. With the help of some supplements and allergy testing, Fiona Took me on a journey of discovery. Thanks to her professional and kind guidance, I now  know which foods to avoid and which ones will help my gut to stay healthy.  For the very first time in a long time, my tummy now feels quite normal and I no longer suffer any of the above conditions. To say Fiona has change my life may sound rather dramatic but it is completely true and I will be forever grateful to her.

Feeling Great, Losing Weight!

I have been working with Fiona at Physical Nutrition for about 10 weeks through a corporate program run my employer.  Losing weight and making some real changes to my dietary lifestyle has been a game changer for me.  Through her weekly tutorials, Fiona has taught me about the food I eat, what is best for my body and to gauge how I feel after each meal.  Combined with a sensible exercise routine of walking and cycling, I have managed to drop my weight by 7kgs during this period.  My energy levels are up, I’m feeling fitter and I’m eating much more balanced meals and now know which foods to avoid and which to eat more of!  It’s been a great experience and I would highly recommend Fiona’s program.

I have recently completed the Physical Nutrition 10kg in 20 weeks program and I couldn’t be more thrilled with the support and guidance Fiona has provided.
The 10 in 20 program not only helped me change my habits by giving me a coach that kept me accountable but also helped to educate me to make better nutrition choices in the future.
Thank you again Fiona & this is just the beginning, I’m not going anywhere ☺️
Paris Doran
Fiona has been working with the City of South Perth over the last year.  She has developed a customised 10 week health coaching and nutrition program with us which the City now offers as part of its suite of health and wellbeing benefits.  All of the participants were overwhelmingly positive about the program.  They rated the program highly on the aspects of Fiona’s professionalism, approachability and knowledge, as well as the results they had achieved.
I would recommend Physical Nutrition to any organisation looking to develop staff benefits.
Gillean Sharp
Physical Nutrition/Fiona Murray has really helped my husband and I to achieve our weight loss and lifestyle goals. Her advice, support and knowledge during the 20 week challenge has set us up to lead a healthier and balanced life style. We thought we had enough food and exercise knowledge before meeting Fiona but she has kept us on track, motivated us and through her group classes has kept us entertained and true to our goals! Thanks Fiona!
Alison Thair
My son is 21 and has been ill for years and part of it was Diet, and we have been to many nutritionalist’s but FIONA MAKES SENSE and TELLS YOU WHY you should be careful what you eat. She changed my sons life so I sent my Daughter who had auto immune issues and she has helped her. It is now my turn so I will keep you updated. Highly recommend her she is also very understanding.
Lisa Mann
I have been with Fiona at Physical Nutrition for several months in relation to skin and gut problems and for weight loss. Fiona is knowledgeable and supportive. I am slowly losing weight and my skin and gut issues are improving. Fiona works in conjunction with my integrative medical practitioner which is a very helpful. First time I have had any positive results, a slow but worthwhile approach.
Lynne Besant


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