One of the best benefits of being fat adapted is the new found joy to move!

Having been a personal trainer for over 10 years, I’ve innocently kept many an individual a sugar burner. The old advice to carb load just simply doesn’t cut it any more, now we understand so much more about metabolic flexibility and the amazing energy source that is fat. I’ve been metabolically flexible and fat adapted now for about 5 years. I’ve had the pleasure of getting many clients fat adapted too since learning the latest science. And what do I mean when I say being fat adapted brings a new found joy to move? Because when your body starts to predominantly burn fat instead of glucose for fuel, your body runs on premium fuel and you find a source of energy you never realised was possible.

And when we have more energy to move, we will naturally keep our bodies healthier and more robust! But let’s look more into what it all means.


Fat adaption is the metabolic reorchestration from a predominant fuel source of glucose to a predominant fuel source of fat.

This is the normal, preferred metabolic state of humans. Before the food pyramid created the obesity epidemic, humans were in a constant yearly cycle of fat adaption, based on factors such as location, climate, season and food supply.

Consider these points:

  1. Fat adaption means you can effectively burn stored fat for energy throughout the day. Even the leanest person who weighs 60kg with 10% body fat, has 6kg of fat or 6000g, which at 9 calories/gram is 54,000 calories to potentially access. Most people will have way more than that though (as opposed to a sugar burner who has a maximum of 2,400 calories)
  2. Fat adaption also means you can rely more on fat for energy during exercise. This offers a glycogen sparing effect, so this fuel (carbs stored in the muscle) is available to support high intensity exercise where it is most required.
  3. For endurance athletes, this is most significant. A simple equation to consider (using round numbers): even a well trained ‘sugar burning’ athlete with 2000 calories of muscle glycogen store, who burns 1000 calories/hour, will obviously run out of fuel at beyond 2 hours. Even if the athlete was able to consume 300 calories/hour, there is still a 700 calorie deficit. The inability to tap into fat reserves is what cause a ‘nutritional bonk’ or ‘hitting the wall’. If you’re an endurance athlete whose splits just get slower and slower during a marathon off the bike or ultra marathon, you need to work on your fat adaption so you essentially never run out of fuel.


  1. Metabolic flexibility is the capacity to adapt fuel oxidation to fuel availability. The advantage of being a fat burner is that you can still burn glucose when necessary and/or available, but you have an almost unlimited reserve of fuel available from fat. Sugar burners only have one fuel option – they can’t effectively access dietary fat for energy, and as a result, more fat is stored than burned.
  2. Glycogen sparing – fat burners can preserve glycogen until its required
  3. Improved performance – the burning of carbs results in the production of lactic acid and reactive oxygen species, which creates oxidative damage that your body must mop up using antioxidants. Fats burn ‘clean’ however, producing only carbon dioxide and water allowing oxidative damage to be avoided, and energy and resources to be prioritised to the recovery process. Faster recovery means you can get back out there and train better
  4. Improved recovery
  5. Injury prevention due to an anti-inflammatory environment
  6. Enhanced immunity
  7. Goal weight becomes easy to maintain
  8. A more efficient metabolism day to day – a decreased desire to snack every two hours
  9. More efficient metabolism in training and racing
  10. Avoidance of GI distress
  11. Increased athletic longevity – as sugar is highly inflammatory, a real food approach is vital if you want to prevent injuries, improve health markers and lower your risk of chronic disease. Eating well and optimising your metabolism means you perform better, remain lean, and stay metabolically healthy as you go up the age group


There are 2 basic strategies:

  1. Eating LCHF – make fat & protein your priorities, and carbs from wholefood sources.
  2. Fasted training. This enhances fat utilisation and decreases reliance on exogenous fuel sources (such as gels etc). Start off slowly though. Keep sessions lower in duration – around 60 mins max. While in this adaption phase, if you need to consume something prior to training, make it coffee, fat black, bullet proof or just a teaspoon of coconut oil (ie fat), and maybe some electrolytes. After training, there is debate on the optimal nutrient timing about when to eat. So my guide is to listen to your body. If you’re hungry after training, then eat a good high protein high fat low carb meal. But if you’re not, your body will rebuild your glycogen stores from ketones, so getting in nutrients post training is about working out what works for you. In fact some research shows that not eating for a couple of hours post training allows your body to become even more fat adapted. Play around with it. Throwing in some carbs (sweet potato, half a banana) post training can work for some people, but not for others.


This happens during transition when there is not enough carbs coming in, and your body hasn’t yet adapted to burning fat efficiently. Initially this can meal fatigue, hunger, and poor performance. How long this takes to adapt is very individual, but if you’re fit and have already made the switch the LCHF, it should only take 3-4 days – but can take up to 6 weeks to see an improvement in performance.


  1. The number one barrier to fat adaption is stress. And the body doesn’t distinguish between internal or external stress – the physiological impact is the same. Extended training can also be a stress on your body. Managing your stress is super important.
  2. Inefficient nutrient timing – continuing to consume carbs prior to a training session instead of after.
  3. Fat phobia and not consuming enough. You cannot cut carbs and not increase your fat. If you’re hungry within 4 hours after eating, you’re not eating enough fat.
  4. Low salt intake. Fat adapted athletes have a much higher salt requirement due to the lower insulin not retaining water in the body, thus flushing out salt too. Salt is needed by our cells for the uptake of essential vitamins and minerals. If you experience poor performance of fatigue beyond the initial adaption phase, look at increasing your salt throughout the day.


  • You can handle missed meals and are able to go for hours without getting ravenous and cranky (or have carb cravings) ie NO MORE HANGRIES
  • You can handle exercising without having the carb load (there will be adaption phase first) and be in a fasted state
  • You don’t get a dip in your energy levels throughout the day
  • Your brain feels clear and unfuzzy

But last of all, give your mind and body time to adjust. It can take some time for things to switch over. Listen to your body, and be guided by that feeling. You will know when it’s all running from the finest fuel.

Want help to become a fat adapted athlete? Anyone can become one. And yes, you are an athlete. If you move out of bed, you’re an athlete. We may not all be elite athletes, but don’t let that stop you! Get in touch with me if you want some help in this area.