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  • HuskNutrition

How to: burn fat

The internet doesn't need another fat loss article.

We look at the cool stuff surrounding fat adaptation that can benefit you.

Torching body fat Vs using fat for fuel is commonly mistaken yet interchanged freely in the physique and fitness industry.

Ask many people on the gym floor about why they started training and most will propose a benefit to body fat or weight reduction.

Increasing fat burning may help you achieve your desired body weight and have a beneficial impact on your endurance but let’s address the fundamental comparison.

Using fat for fuel refers to using the fat that is consumed in the diet for energy.

Burning body fat refers to using the fat that is stored in the body as a source of energy.

The fat that is consumed in the diet is readily available for use as fuel, whereas burning body fat requires the body to first break down the fat stores before they can be used for energy.


  • To lose weight, you must create a deficit in your body's energy balance by burning more calories than you consume.

  • By increasing your body's ability to burn fat, you can increase the percentage of calories burned that comes from stored body fat.

Our bodies burn all three macronutrients that make up calories (fat, carbohydrate, and protein) for energy, but most of our energy comes from carbohydrates and fats.

Increasing the percentage of energy expended from fat means a decreased percentage of carbohydrates, and vice versa, like a seesaw effect.

To maximise fat burning, it's important to focus on aerobic/endurance exercises such as jogging, cycling, swimming, rowing, skipping, and cross-country skiing.

During these exercises, energy is produced by combining carbohydrates, fats, and a minimal amount of protein calories with oxygen. Oxygen is a crucial factor.


At rest, the body uses fat as a fuel source, as we elevate heart rate and muscular activity this stimulates blood flow and enzymes which takes oxygen, glucose and other nutrients to the working muscles, allowing them to use carbohydrates as a fuel source in addition to fat.

As intensity and exercise duration gets higher, we use up ATP (think of this as your onboard battery pack that can be recharged) more blood glucose has to be synthesised (from muscle tissue, blood glucose, and liver) to feed further energy production.

The body may also start to break down muscle tissue to use as an energy source in addition to fat and carbohydrates.

This is why it is important to properly fuel the body with carbohydrates before and during high-intensity and long-duration exercise to prevent muscle breakdown and maintain energy levels.


Using fat from the diet for fuel is generally less efficient than burning body fat. This is because the body needs to first break down the dietary fat into smaller molecules before it can be used for energy, whereas body fat is already in a form that can be readily used.

Fatty acids


Carbohydrates fructose and glucose

Burning body fat can lead to weight loss as weight is not only fat, BUT it is not a predictor of reductions in body fat percentages.


1lb of fat is said to equate to 3500k/cals.

To lose 1 lb of body fat alone, you have to preserve muscle tissue fiercely (resistance training and protein intake) whilst you support the basic metabolic needs of your body, reduce energy intake or promote further output over some time.

Over 7 days you would need to create a -500k/cal per day deficit - this could be done by reducing your dietary calories by 250 and increasing expenditure by 250 (both from your current baseline) to create a 500 calorie deficit.

7 days -500 = - 3500 calories - -1lb of fat

Stay with us.


Fat adaptation is a metabolic process in which the body becomes more efficient at using fat as a fuel source during exercise.

This happens when the body is repeatedly exposed to low-carbohydrate, high-fat diets and prolonged exercise sessions.

When the body is in a low-carbohydrate state, it turns to fat stores to provide energy for exercise.

Over time, the muscles become better at using fat as a primary fuel source, which can enhance endurance performance and increase the availability of energy during long-duration exercises.

Fat adaptation also involves changes in the body's enzymes and metabolic pathways to better utilise fat as a fuel source.

These changes include an increase in the activity of enzymes involved in fat oxidation and a reduction in the activity of enzymes involved in carbohydrate metabolism.

As a result, the body becomes more efficient at using fat as a fuel source and conserves its limited carbohydrate stores for high-intensity exercise.

According to research, it typically takes 2-4 weeks of consistently following a low-carbohydrate, high-fat diet and consistent training. It may not be suitable for all athletes. low-carb diet to become fat-adapted.

However, the duration may vary depending on individual factors such as metabolism, exercise routine, and overall health.

There is no specific g/kg of bodyweight recommendation for macronutrients to become fat-adapted. However, most low-carb or ketogenic diets recommend consuming a high amount of fat, moderate protein, and very low carbohydrates.

Combine this with understanding your Total Daily Energy Expenditure (we do this for our clients) you can refine the numbers.

Typically, the macronutrient ratio for a low-carb diet is 60-75% fat, 15-30% protein, and 5-10% carbohydrates. 1,2,3

Most athletes do well aiming for 20% protein, 60% fat and 20% carbohydrates to begin, emphasised around the workout window.

For example, only, a male maintaining their weight at 2500k/cals per day would aim for 125g protein, 125g carbohydrates and around 167g of high-quality fats during this phase.

As for the duration of time, it takes to become fat-adapted, it may take anywhere from 2-4 weeks of consistently following a low-carb diet to enter a state of nutritional ketosis and become fat-adapted.

The exact duration may vary from person to person depending on various factors such as age, gender, activity level, and overall health status. 4,5,6

We don’t advise that this is a long-term lifestyle strategy, we are objectively looking at the outcomes and information and these have to be considered within the context of your lifestyle.

More later.


Fat max is a term used to describe the exercise intensity at which the highest amount of fat is burned for energy during endurance exercise.

It is typically measured by analysing the respiratory gases of an athlete during exercise using a technique called indirect calorimetry.

This involves measuring the oxygen consumption and carbon dioxide production of the athlete while they exercise at different intensities.

By analysing the ratio of these gases, it is possible to determine the amount of energy being derived from carbohydrates versus fats.

Bodybuilders tout the use of LISS cardio (walking) as a method of fat burning but understanding fat max shows that knowing your fitness level changes the typical range that your body burns the highest proportion of fatty acids for you.

Depending on the health of your cardiovascular system and your training principles these levels will increase and decrease.

People will be more commonly familiar with ‘zone’ training or using Watts as a measure of consistent output, each zone utilising different energy pathways and training different energy systems.

According to Professor Jeukendrup and his research team at the University of Birmingham, moderate-intensity exercise (62-63% of VO2max or 70-75% of maximum heart rate [HRmax]) was found to be the most effective intensity for fat oxidation in trained subjects. 7

However, in individuals who are less trained, fat max was found to occur at only 50% of VO2 max.

The exercise intensity at which the highest amount of fat is being burned is known as the ‘fat max’ intensity.


Knowing an athlete's fat max intensity can be useful in designing training programs for endurance events such as marathons or triathlons or long days of competition.

By training at or near the fat max intensity, improving VO2 max and using nutrition, the athlete can improve their ability to use fat as a fuel source, which can help them conserve their limited carbohydrate stores for later in the race when they may need them the most.


This is a targeted approach for fat adaptation and fat burning.

An exercise programme that contains work effort around 60-80% of your heart rate, for around 60 minutes at a frequency of 3 sessions per week, or 6 sessions of 30 minutes.

Build up your sessions gradually as you become adapted to the diet to avoid the risk of injury or burnout.

For the first 14 days, follow a 20/20/60 macro split at your maintenance calories whilst adding endurance sessions to your programme, and assess your outcomes.

Using fats that provide MCT’s also shown during this time to increase switching to a fat-burning metabolism, these include coconut oil, palm kernel oil, and MCT oil. Include omega-rich fat sources such as grass-fed butter, flaxseed, chia, olives, olive oil, avocados, nuts and nut butter as well as some dairy fats such as cream, full-fat yoghurts and cheeses but make sure to include them into your carbohydrate intake.

It would be advisable to assure carbohydrates limit fructose and use low glycemic carb sources such as dark thin-skinned berries, green vegetables, root vegetables and moderate cereals/grains during this time.

Use high-quality protein sources such as eggs, chicken, turkey, beef, lamb, peas, hydrolysed whey protein, and vegan protein powders and omit low-quality protein sources such as protein mousses, yoghurts, protein bars heavy in soy and powdered peanut butter. 8


Fat adaptation and body composition are only ever one phase of an athlete's annual programming.

It is not a sustainable diet for many people and we make this very clear.

Carbohydrates are always going to bine around us and we need them for our health to supply vitamins and minerals for energy metabolism. If you read this and ultimately think this is the holy grail, think again, users of our 14-day fat loss programme will attest to experiencing a range of physical, mental, and emotional changes, including:

Physical changes in body composition with a temporary decrease in performance whilst adjusting to using fat as a fuel source.

Mental changes feeling naturally focused as fat provides a more sustained source of energy for the brain compared to carbohydrates.

Emotional changes in a low-carbohydrate diet can be challenging and may lead to frustration, fatigue, and irritability during adaptation.

Cold-like or flu-like symptoms.

Lack of endurance capacity initially.

However, many athletes report feeling more satisfied and less hungry on this type of diet, which can lead to a more positive mood overall.

It's worth noting that the effects of fat adaptation can vary widely from person to person.

Athletes who are considering a high-fat, low-carbohydrate diet should closely consider the cost/reward benefits of this.

We employ strategies to sensitise and assist fat loss and muscle building with clever nutrition.

Going back to energy pathways, glycolysis and gluconeogenesis are both metabolic pathways involved in the production of glucose, but they have opposite functions.

The glycolytic pathway is a catabolic pathway that breaks down glucose to produce energy, while gluconeogenesis is an anabolic pathway that synthesises glucose from non-carbohydrate sources.

Shown below we can see the pro- and preceding functions of these two pathways.

Simply put, our bodies use sugar, if we don't eat it, we make it by breaking down (catabolise) our body or dietary fat and protein (body fat, circulating fat or muscle protein) to rebuild us (anabolic).

Therefore, it is an expensive pathway in the body to use fat and protein, it costs you to fuel you.

Carbohydrates are broken down into glucose, which our body uses for energy. Insulin is released to help transport glucose into our cells and store any excess glucose for later use.

Insulin is like a key that unlocks the doors to our cells, allowing glucose to enter and be used for energy. It also helps to store excess glucose in the liver and muscles for later use.

N.b leucine is an important amino acid (from protein) that works together with insulin. We have identified protein sources.

If we eat too many carbohydrates, our body may not be able to use all of the glucose for energy, and insulin will continue to be released, causing the glucose to be stored as fat.

This can lead to weight gain and other health problems.

It is important to eat carbohydrates relative to your demands to maintain a healthy balance of energy and prevent excess fat storage.

Therefore, at the start of tidying up nutrition, it might be prudent to re-sensitise this process and stimulate the effect of insulin and blood sugar regulation.

If you’re sitting at a desk all day and training with traditional bodybuilding 3 sets of 12 plus whatever rest you fancy for 50 minutes, it may be prudent to time your carbs around that effort and not at breakfast before a day of spreadsheets.


We can look at these principles over a day AS AN EXAMPLE ONLY, for transparency we have intentionally left out some information about daily totals and these are hypothesised initial examples.

Based on an 80kg general population male aiming for 4g cho per kg (average for much lower intensity training, once per day), a total of 320g

This athlete's requirements based on the physical demands and activity are calculated.

320g (1280k/cals), which will come from carbohydrates.

Example A:

If you train fasted in the morning.

Wake | hydrate with electrolyte/caffeine blend such as HMN24 RISE.

Sip on a 2:1 fructose: glucose carbohydrate blend during training, typically 60g carbs p/h of training.


After training, a meal containing 1g/kg of higher glycemic carbohydrates.


At lunch, a serving of HMN24 FLOW 30-45mins before food and another meal containing 1g/kg of carbohydrate using low glycemic sources.


A snack bar containing 20g carbohydrates.


Evening meal consisting of 60g low glycemic carbohydrate with a dose of HMN24 PRE-SLEEP 1-2 hours before bed.


20g carbohydrate before bed.


We taper carbohydrates away from training.

Example B

The same athlete trains at 6 pm, therefore we taper the carbs slightly lower in the morning.

Wake | hydrate with electrolyte/caffeine blend such as HMN24 RISE.

Breakfast contains 60g of low-glycemic carbohydrates.


Mid-morning a snack bar containing 20g carbohydrates.


At lunch, a serving of HMN24 FLOW 30-45 mins before food and a meal containing 50g low-glycemic carbohydrate.


Pre-workout a serving of 30g carbohydrates. If this is very close to the workout (<60mins) consider this to be high glycemic carbohydrates.


Sip on a 2:1 fructose: glucose carbohydrate blend during training, typically 60g carbs p/h.


In the evening, a meal containing 1g/kg of high-glycemic carbohydrates with a dose of HMN24 PRE-SLEEP 1-2 hours before bed.


<20g carbohydrate before bed.



  1. Volek, J. S., Noakes, T., & Phinney, S. D. (2015). Rethinking fat as a fuel for endurance exercise. European Journal of Sport Science, 15(1), 13-20.

  2. Hall, K. D., Chen, K. Y., Guo, J., Lam, Y. Y., Leibel, R. L., Mayer, L. E., ... & Ravussin, E. (2016). Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. The American Journal of Clinical Nutrition, 104(2), 324-333.

  3. Paoli, A., Rubini, A., Volek, J. S., & Grimaldi, K. A. (2013). Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition, 67(8), 789-796.

  4. Phinney, S. D., Bistrian, B. R., Evans, W. J., Gervino, E., & Blackburn, G. L. (1983). The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism, 32(8), 769-776.

  5. Burke, L. M., Ross, M. L., Garvican-Lewis, L. A., Welvaert, M., Heikura, I. A., Forbes, S. G., ... & Hawley, J. A. (2017). Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. The Journal of Physiology, 595(9), 2785-2807.

  6. Phinney, S. D., Horton, E. S., Sims, E. A., Hanson, J. S., Danforth, E., & LaGrange, B. M. (1980). Capacity for moderate exercise in obese subjects after adaptation to a hypocaloric, ketogenic diet. Journal of Clinical Investigation, 66(5), 1152-1161.

  7. Jeukendrup, A. E., Saris, W. H., Wagenmakers, A. J., & Senden, J. M. (1998). Fat metabolism during exercise: a review—part I: fatty acid mobilization and muscle metabolism. International Journal of Sports Medicine, 19(S 02), S1-S14.

  8. Mousavi, S. N., & Mousavi, S. M. (2021). Fat Adaptation: Current Concepts and Review of the Literature. Journal of Nutrition and Metabolism, 2021.


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