Fat adaptation is the metabolic reorchestration from a predominant fuel source of glucose to a predominant fuel source of fat. In other words, when you are fat adapted, your body can recognise fat as its primary fuel source rather than carbohydrate. This is the preferred metabolic state of the human.

The process of fat adaptation starts with JERF (Just Eat Real Food) and LCHF (Lower Carbohydrate, Higher Fat) and can take 8–12 weeks, but please keep in mind that this is highly dependent on the level of carbohydrate restriction and the individual at hand. To find out more about becoming fat adapted, read this.

One common question we get asked here at TNN is ‘How will I know when I am fat adapted?’ This is a very valid question so we thought we would share a few signs to give you some clarification on the matter and tell you if your body has reached a state of fat adaptation.

Our top 5 signs that you’re a fat adapted athlete are:

  1. You have stable blood sugar levels 

Burning fat for energy will break the vicious cycle of the blood sugar rollercoaster, or the severe highs and lows that accompany a sugar-burning metabolism. This is often one of the first benefits observed with fat adaptation, and a sign you are keeping your insulin (our fat storage hormone) levels in check. The metabolic benefits of low insulin are many, including a body that is primed to burn, rather than store, fat.

  1. You have excellent satiety between meals

Can you go 5 hours without needing your next meal or snack? Appetite control is one of the many amazing benefits of fat adaptation. On the other hand, if you are always carrying a muesli bar or piece of fruit “just in case you get hungry”, then it is likely that you have poor blood sugar control, a sugar-burning metabolism and a body that is geared to store fat. We only need to look to our ancestors to see that periods without food are extremely healthy, but unfortunately our current constant supply of food, and incorrect education and media messaging around meal times and frequency, have us bound by our appetites and resorting to calorie restriction in a futile attempt to shift body fat.

  1. Elimination of the ‘hangries’ (hungry + angry)

The stable blood sugar created by fat adaptation can be quite life changing as you are no longer dependent on your appetite, or counting down the minutes until your next meal (or sugar fix). Too many of us experience the hangries on a daily basis and accept that it’s normal, when it’s a complete by-product of our previous meal choice/s. Shifting towards burning fat for fuel not only keeps blood sugar levels in check, but it prolongs energy and doesn’t leave room for mood swings and the hungry/angry feeling that comes with a sugar-burning state and the urgent need for your next fix.

  1. You can extend your overnight fast 

The word breakfast can be defined as “the first meal of the day especially when taken in the morning”, however it really means “breaking the fast” and does not need to be at 7am (or any defined time of the day). Extending your overnight fast, and comfortably eating your first meal mid-morning (for example), is an excellent example of the capacity of a fat-burning metabolism. Please note: if you have always eaten breakfast at 7am you can expect to feel hungry at this time, but often it is ghost hunger as your body has been programmed this way over many years. Over time you can reverse this habit and the more you JERF/LCHF, the easier it will become.

  1. You have the ability to train in a fasted state for 2+ hours

If you can train effectively in a fasted state for over 2 hours, you are definitely fat adapted. A sugar-burner will use up their glycogen stores very quickly and therefore require an exogenous source to continue exercising beyond the 2-hour mark. When your body relies on fat as its main source of energy during exercise, there is more than double the amount of calories available (carbohydrates contain 4 calories per gram, while fat provides 9 calories per gram). This fat-burning ability also has a glycogen sparing effect, so that the carbohydrate stored in muscle is available to support high intensity activity (where it is most required). Please note: unless you are an extremely well fat adapted athlete we don’t recommend fasted training beyond 3 hours. There are also effective strategies that should be implemented so as to not become catabolic during this time.


Credit to Steph @www.thenaturalnutritionist.com.au for the story