Bust The Myth – You can’t Gain Muscle & Lose Body Fat at the same time.

The fitness industry can be a funny place at times, especially when it comes to claims that sound too good to be true. These tend to create a divide of belief or opinion. So EQ Nutrition wants to create a series of evidence based perspectives that can help Bust the Myth.

I got into chatting to some members at the gym about their goals and drive for being there, “I want to get stronger” “I want to fit into my holiday clothes” “I just want to look at myself and be happy” were a few – but most tended to come down to “I want to build some muscle and burn some fat.”

Don’t we all!

However, thats poses a dilemma as we are all fed the same line that:

  • In order to build muscle you need to consume surplus excess calories
  • In order to lose fat there must be a calorie deficit


What is a calorie surplus?
We consume calories in our day-to-day diet from macronutrients (proteins, carbs and fats). They are the units of energy we use or store in the body for different purposes. A calorie surplus occurs when more calories per day are consumed than burned, with energy leftover as a result.

What is a calorie deficit?

A calorie deficit comes when we burn more calories per day than we consume through diet. These calories will be burnt through your metabolism and activity levels.

So isn’t this myth a contradiction from the off? How can I consume surplus calories but also be in a deficit?

The Body of Evidence – Is High Protein Intake the key?

A study at McMaster University indicated that a dietary protein intake higher than the Recommended Dietary Allowance during an energy deficit helps to preserve lean body mass (LBM), particularly when combined with exercise.

The purpose of this study was to conduct a proof-of-principle trial to test whether manipulation of dietary protein intake during a marked energy deficit in addition to intense exercise training would affect changes in body composition.


For the study, 40 young men underwent a month of hard exercise while cutting dietary energy they would normally require by 40 per cent.
These young men were in rough shape, but that was part of the plan. The study wanted to see how quickly they could get them into shape: lose some fat, but still retain their muscle and improve their strength and fitness.
The researchers divided their subjects into two groups. Both groups went on a low calorie diet, one with higher levels of protein than the other. The higher-protein group experienced muscle gains – about 2.5 pounds – despite consuming insufficient energy, while the lower protein group did not add muscle.

The lower-protein group at least had the consolation of not losing muscle, which is a predictable outcome of cutting calories and working out.

Exercise, particularly lifting weights, seemed to provide a signal for muscle to be retained even when you’re in a big calorie deficit. Researchers were intrigued because the high-protein group also lost more body fat.
The results showed that the high-protein group lost about 10.5 pounds and the low protein group eight pounds. All of the participants, by virtue of the demanding six-days-a-week exercise routines, got stronger, fitter, and generally were in much better shape.
However, researchers caution this regimen is not for everyone.

The study was designed for overweight young men, though I’m sure it would work for young women too, to get fitter, stronger, and to lose weight fast. They controlled the diets, supervised the exercise, and kept these study group under strict adherence for the four weeks the participants were in the study.
The same team hope to conduct a follow-up study on women and also explore a different approach that may be “a little easier and much more sustainable.”

So the Body of Evidence seems to indicate you could use the fat as the energy source to build muscle? So more a question of thermodynamics or the way the body both uses and stores energy? In essence Energy Balance.

Energy Balance

Energy balance is the relationship between:

  • “energy in” (food calories taken into the body through food and drink) and
  • “energy out” (calories being used in the body for our daily energy requirements).

This relationship, which is defined by the laws of thermodynamics, dictates whether weight is lost, gained, or remains the same. According to these laws, energy is never really created and it’s never really destroyed. Rather, energy is transferred between entities.
We convert potential energy that’s stored within our food (measured in Calories or kcals) into three major “destinations”:

  • Work
    • Physical Work (Exercise or Activity)
  • Heat
    • Heat produced with physical work
    • Heat produced via the thermic effect of food (TEF)
    • Heat produced by resting metabolism
    • Heat produced: adipose creation
    • Heat produced: adipose thermoregulation
  • Storage
    • Efficiency of work
    • Efficiency of food metabolism
    • Energy stored in adipose tissue

When it comes to “energy out,” the body’s energy needs include the amount of energy required for maintenance at rest, physical activity and movement, and for food digestion, absorption, and transport.

Thermodynamics can be referred to as ‘the conversion of energy’ so it’s possible for 


your body to take energy from one source and use it for any another purpose if it sees fit. So gaining muscle whilst losing fat involves converting that potential energy from your bodies fat cells.

If you wish to change your body composition, it’s imperative you provide it with the correct stimulus (training) and intake the correct energy. If this is done correctly you can utilise fat stores as energy and build lean mass at the same time, changing your body composition over time, even when in a calorie deficit.

Please note that it is impossible for fat tissue to directly turn into muscle tissue but you can trade that fat for muscle by using it for fuel.

Body Fat the Solution

You need sufficient calories to build muscle and you need a deficit to burn fat. However, body fat is actually a solution!
Body fat is stored energy or stored calories. If you don’t meet your caloric needs through food, you tap into your ‘stored calories’ to do the job. Since those stored calories are in the form of body fat, you therefore have to lose fat in order to build that muscle.

If for example you eat 500 calories less than your body needs to get through the day (your maintenance calories including exercise). How will your body get those extra 500 calories needed to energise you and build muscle?

By burning your body fat. There are about 3500 calories in a pound of fat.

  • 500 calories X 7 days = 3500 calories,

In Theory you fuel protein synthesis (building new muscle) and lose 1 pound of fat per week in the process – that’s nice, very nice.

Exercise does improve fat metabolism in muscle, thought there is no clear understanding how exercise helps to regulate fat mass.


Your body is able to utilise energy from fat to both build muscle and burn unwanted fat. The energy is still being used whether the body is in a calorie deficit or surplus. You are just adjusting the amounts of calories to support the intended outcome. Meaning body composition can be changed throughout.

Supporting Studies:

Energy Balance – https://www.nhlbi.nih.gov/health/educational/wecan/healthy-weight-basics/balance.htm

Laws of Thermodynamics – Bailey, Regina. “Laws of Thermodynamics as Related to Biology.” ThoughtCo, Jul. 15, 2017, thoughtco.com/laws-of-thermodynamics-373307

Thomas M Longland, Sara Y Oikawa, Cameron J Mitchell, Michaela C Devries, and Stuart M Phillips. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. American Journal of Clinical Nutrition, January 2016 DOI: 10.3945/ajcn.115.119339

Exercise improves fat metabolism in muscle but does not increase 24-h fat oxidation – Melanson, MacLean, Hill June 2010 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2885974/