Fat-adapted training

Fat-adapted training is essentially where your body primarily burns fat for energy – stored body fat or dietary fats. It is based on the premise that our bodies should (and for thousands of years, did) rely primarily not on carbs for fuel, but on fat. Runners need to fuel correctly to stock up their energy stores and now there’s a growing body of evidence to suggest the dominant approach to sports nutrition, based primarily on using carbohydrates as workout fuel, may not be the most effective.

The body can only store a small amount of glycogen (stored carbohydrate), enough for about 90 minutes of exercise, so we are advised to keep topping up during an endurance event. Not doing so, as we have learned, runs the risk of hypoglycemia or the dreaded ‘nutritional bonk’ where the body has exhausted the supply of energy from blood sugar. The dependency on sugar to fuel energy can lead to withdrawal when it’s not available. Can you go more than three hours without eating? Do you get moody if you miss a meal? Do you feel like your energy goes up and down throughout the day? Do you crave sugar? All of these signs point to glycogen dependency. We’ve just become so used to it, we see it as normal.

The solution, as many sports nutritionists now believe, is to wean ourselves off our reliance on carbohydrates as a primary source of energy and retrain our bodies to use their fat reserves for the bulk of their energy needs. It is particularly useful for runners covering long distances and who would ordinarily have to keep topping up their energy stores.

Fat adaptation is related to but distinct from a separate process known as ketosis. Followers of a ketogenic diet consume very low levels of carbohydrate. It’s possible however to follow a lower carbohydrate diet that encourages the body to use more of it’s fat resources as fuel but stopping short of the more extreme, ketosis.

While our carbohydrate stores are limited, our stored fat, even in a lean body, has enough to power us for 24 hours and well beyond. Stored fat delivers a stable energy base which doesn’t stress the body and mind anywhere near as much as the roller-coaster energy of carbohydrate fueling and without the potential gut issues from consuming so much sugar. So for endurance runners with sensitive digestion, I would particularly recommend it.

The drawbacks during transition to a fat-adapted state are commonly: sugar cravings, obsessive thoughts of carb-based foods, mood swings and an initial decrease in running performance. For this reason, many runners dread the transition phase and many people just aren’t motivated enough to endure the potential side effects. So it really comes down to how much you want it and if you are a long distance runner.

So if you’ve decided you want to become fat-adapted you need to begin to limit your carbohydrate intake to less than 150g a day and then keeping it around 100g a day but it’s not just a question of reducing carbohydrate intake, you need to replace these calories with essential fats such as; oily fish, eggs, dairy, meat, nuts, seeds, avocados and oils. When cutting carbohydrate, aim to eliminate poor quality, processed sugars and draw your carbohydrate needs from whole foods such as vegetables, berries and potatoes which also contain lots of other nutrients.

A typical meal plan might look like this:

Breakfast: scrambled eggs, smoked salmon, spinach and avocado

Lunch: chicken or turkey with a mixed salad, feta cheese and olive oil

Snack: nuts, seeds, berries and natural yoghurt

Dinner: salmon or mackerel with sweet potato and vegetables.

Ways to enhance fat-adapted training

We’ve all got stored body fat already, even in the leanest of athletes. The trick is accessing it for performance. This requires three simple training and dietary changes which are:

  • Reduce sugar and processed foods in your diet – the more of these in your daily diet, the more your body will depend on them.
  • Increase essential fats in your diet as detailed above – more essential fat helps your body recognise these fats as a primary fuel source.
  • Fasted-state training – try going out for a run first thing in the morning on an empty stomach but be sure to drink plenty of water beforehand. Black coffee can also be helpful, consumed 30 minutes before running as it allows your body to release stored fat more rapidly.

Did you know?

You’ll know you’re fat-adapted when you can miss a meal and still be able to function, find your energy levels even and steady throughout the day and you don’t get strong cravings for food or sugar. As your training progresses and your endurance increases, you’ll find yourself reaching less and less for the snacks and gels and you’ll be surprised how far you can go.

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