Ultimately we should always train for our specific goals – and generally those often fall into the two categories of losing fat or gaining muscle. However, we all want the best of both worlds, but is it possible?

Generally, losing fat and gaining muscle are seen as opposing goals, since at a basic level losing fat means being in a deficit, while gaining muscle relies on being in a calorie surplus.

So if we want to achieve fat loss WHILE gaining muscle, what we are really aiming for is body recomposition.

This recomposition is possible, but only for certain individuals, since our ability to gain muscle decreases with body fat percentage and training experience, when in a calorie deficit.

Those with high body fat and little training experience will see the most return; this is often referred to as “newbie gains.”

body composition


Gaining Muscle:

Our bodies are constantly in a  state of maintenance and repair, always  breaking down and building up – basically, whereby damaged cells are destroyed and new cells are created, in a  process of protein degradation and protein synthesis.

Since our bodies are always after homeostasis, this process of cell regulation remains fairly stable, so that our lean mass remains level on a day-to-day basis.

When we train, effectively we are damaging the cells in muscle fibres, creating signals calling for a new adaptation, where the body needs to increase protein synthesis in order to repair the damage. In order to become more effective, over time the body further adapts to this by also adding more cells to the muscle fibres, in anticipation of the now heavier workloads. This is what results in muscle growth, and why progressive overload is such an important factor when training to increase muscle.

Simply put, when protein synthesis rates exceed protein breakdown, we build muscle. Likewise, we lose muscle when the body creates less muscle proteins than we lose, and muscle remains fairly the same when protein synthesis and breakdown are equal.


Losing Fat:

The most important factor for losing fat is creating an energy deficit, whereby more energy  is used by the body than it takes in. However, over time the body adapts to a calorie deficit by reducing anabolic hormone levels and protein synthesis – which directly effects the body’ ability to then create new muscle. Since, in a deficit, protein degradation rates will be higher than protein synthesis, resulting in no muscle growth, and potentially the eventual loss of muscle.

How then, can recomposition occur?

When we first start training, the stimulus is new to the body which means we are hyper-responsive and so can gain muscle at a faster rate – a rate that is only slightly infringed by a calorie deficit.

Obviously, we would be able to gain more muscle if in a calorie surplus, but even slowed down muscle growth can mean a change or recomposition of fat and muscle. That’s why those new to training will see the most dramatic results. Unfortunately that also means those who have already achieved a major portion of their genetic potential for muscle growth will see fewer results, since they have already become adapted to the stimulus of training. In terms of numbers, that could mean men new to weight training could gain upto 25 pounds of muscle in their first year, with women able to gain potentially half that amount, while someone who has already trained for several years might now only be able to only gain 3-5 pounds of muscle a year. This means, those with training experience benefit more from a split approach of first gaining muscle in a bulking phase and then losing fat in a cutting phase.

fat vs muscle

The differences between fat loss and muscle gain mean that:

– Fat is far quicker to lose so we will see quicker visual results, while muscle building is a slower process since it requires the building of new tissues.

– Large surpluses or bulking will increase muscle growth but will also result in some fat gain

>so we should use a larger deficit to create fat loss, and a smaller surplus to build muscle.


In order to effect both processes and achieve Body Recomposition we need a moderate deficit

– enough that we lose fat, but too much that our energy and hormone levels drop and we can no longer create new muscle.

Research has shown that the ideal range of deficit needed is between 20-25%.



How to set up a Recomposition Diet:

When it comes to setting up a diet, we always need to start with calculating our maintenance calories, before determining the level of deficit to create.

Step 1 – Calculate your BMR: 

These are the calories we need to maintain our bodies while at rest. There are numerous calculators and formulas, and here are two popular ones:


Harris-Benedict Formula

(Less accurate, but no need to know your body-fat percentage)



Women: BMR = 655 + (9.6 x weight in kilos) + (1.8 x height in cm) – (4.7 x age in years)

Men: BMR = 66 + (13.7 x weight in kilos) + (5 x height in cm) – (6.8 x age in years)




Women: BMR = 655 + (4.4 x weight in lbs) + (4.6 x height in inches) – (4.7 x age in years) 

Men: BMR = 66 + (6.2 x weight in lbs) + (12.7 x height in inches) – (6.8 x age in years)


Katch-McArdle Formula

(More accurate, if you have a good idea of your body-fat percentage) 


BMR (men and women) = 370 + (21.6 x lean mass in kg)


BMR (men and women) = 370 + (9.8 x lean mass in lbs)


To gauge body fat percentage there are a variety of methods, but none of them are perfect. Try using body fat calliper measurements if you are already fairly lean, or Bioimpedance devices or scales (however they fluctuate widely and cannot detect small changes), or online calculators that rely on height, weight and body measurements.

Other options include DXA, Bodpod/underwater weighing and X-ray and MRI – which although more accurate are vastly more expensive.

We always need to remember that these are ESTIMATES so can only give us a general figure.


Step 2. Adjust for Activity:

You need to add a multiplier for activity to your BMR depending on your lifestyle/training.

  • Sedentary(little or no exercise): BMR x 1.2
  • Lightly active(training/sports 2-3 days/week): BMR x 1.375
  • Moderately active(training/sports 4-5 days/week): BMR x 1.55
  • Very active(training/sports 6-7 days a week): BMR x 1.725
  • Extremely active(training/sports and physical job): BMR x 1.9

Again, we need to remember these calculations will get us a likely range – since even general activity levels including NEAT will differ between individuals. Also these estimates certainly don’t take into consideration the individualized metabolic adaptations we have created over time – meaning the amount of calories we have “taught” our bodies to run on.

BMR x activity multipler = TDEE

Total Daily Energy Expenditure gives us a starting point to test from. But it’s always best to track these calories against weight for a few weeks and adjust.


Step 4 – Calculate the deficit required:

TDEE – 20-25% deficit = recomposition calories


Step 5 – Track and Adjust upwards or downwards based on how your weight reacts.

 Using formulas will always provide us with an estimate, so it’s always important to track and adjust our calories as we go.



Other factors to consider:

  • Training should be centered on heavy, compound movements which recruit more muscle fibres, and increase muscle breakdown. Whereas we should limited cardio to short, intense sessions such as Hiit rather than long bouts of steady-state – which will effectively teach our bodies to drop muscle in order to become more effective.
  • Sleep is vital to muscle growth and fat loss, as that is when the body actually repairs itself. Sleep deprivation can cause disruption to hormone levels, and so disrupt our ability to build new cells. While it can also cause cortisol levels to increase, and can mean increased appetite and lower energy levels, which can in turn effect our ability to adhere to our diets and achieve fat loss.




  • Losing Fat and Gaining Muscle is possible through body recomposition, but at a reduced rate when in a calorie deficit. And it’s only possible for some individuals – those either already overweight, or new to training, since our ability to gain muscle decreases with body fat percentage and training experience.

  • Body Composition change requires a Moderate deficit of between 20-25%

  • We need to use heavy, compound resistance training and use Hiit style cardio sessions, whilst getting enough sleep



better bodies

Contact us for further advice on:

  • Personal Training in Barnstaple and North Devon
  • Weight training and Individual Weights Programs
  • Personalised Nutrition