Losing fat whilst gaining muscle or “toning up” is a common goal. However, there are a few questions worth considering. Is it possible to do BOTH at the same time? And if so, is it a worthwhile pursuit? Could it be significantly quicker to focus on one or the other at a time?
The reason why this is a topic worth addressing is because muscle building and fat loss are actually two contradictory physical mechanisms.
You may have heard of the two metabolism states: anabolism and catabolism. These basically refer to either your body using energy to grow (anabolism) or breaking down energy for fuel (catabolism).
Muscle building is deemed an opposite metabolic state of fat loss. Muscle building is anabolic; your body uses energy to build muscle. Fat loss is catabolic; your body needs energy, therefore breaks down fat to provide energy for your bodily needs.
This is why the question exists:
Is it possible to gain muscle and lose fat simultaneously?
What Does the Evidence Say?
One 4-week study investigated the effects of a 40% calorie deficit and high protein diet (2.4g/kg) vs a lower protein diet (1.2g/kg) with overweight participants new to resistance training.
The two groups underwent resistance training six times a week and all meals were provided throughout the study. The high protein diet gained an average of 1kg of muscle mass, whereas the lower protein group only maintained muscle mass, indicating the need for increasing protein intake to achieve muscle building and fat loss simultaneously.
But what about lean individuals? A study investigated the effects of weight training exercise regimes on lean college volleyball female athletes. After 7 weeks of training 3 times a week, the athletes lost an average of 2.1kg of fat mass and increased 2.7kg of muscle. Participants met with a dietitian weekly and their protein intake was an average of 1.7g/kg of protein per day.
Another similar study compared the effects of 9 months of resistance training on the body composition of female tennis athletes. Athletes were young, lean, new to weight training, and lost on average 2% body fat, whilst gaining 1.8kg of lean muscle mass.
One factor contributing to these results could be the differences in training stimulus.
The exercise regimes both studies used involved squats, deadlifts, and bench-pressing; different types of training compared to volleyball and tennis.
The athletes were likely training more appropriately for muscle growth than the methods utilised prior to the study, therefore muscle gains were more easily achieved than what would be expected of an experienced weightlifter undergoing a similar study.
A Broader Look at the Research
A large review on this topic analysed 57 studies comparing calorie deficits vs maintenance calorie diets in resistance training individuals.
The study found energy deficits lead to smaller muscle building and strength gains (however some still gained) and a calorie deficit of 500 calories/day or more typically prevented muscle growth. The below images from Stronger By Science covers this well.
Is Bulking Necessary or Can You Build Muscle Well Enough in a Deficit?
There are several factors influencing muscle growth during an energy deficit. Certain muscle-building hormones such as insulin-like growth factor-1 (IGF-1) are anabolic and when in a calorie deficit, anabolic hormones may not function as efficiently; resulting in muscle protein synthesis not as increased as desired for optimal muscle building.
These hormones have a “dose-dependent response” to calorie reduction. Basically, the greater the calorie deficit the greater the loss of function of the hormones and the harder it is to build muscle.
There are several advantages a caloric surplus provides that a calorie deficit does not, such as:
- Increase of anabolic muscle building hormones (faster muscle growth)
- More energy to train heavier and increase progressive overload for optimal muscle gains
- Increased glycogen stores to fuel high-intensity workouts
- Increased mood and cognition
- Improved sleep
So, although it is possible, it is far less efficient to build muscle in a deficit. To maximise muscle growth, it makes sense to spend some time in a surplus.
How Many Calories Should You Eat to Gain Muscle and Lose Weight?
If you want to pursue both muscle gain and fat loss at the same time, a small deficit makes sense.
As calorie deficits up to 500cal/day are more likely to result in both muscle gain and fat loss than larger deficits, you’re looking at a deficit window of ~100-500cal per day. (It is important to note that as you lose or gain weight, calorie changes will need to be adjusted accordingly due to metabolic adaptation.)
Exact calorie requirements all come down to individual circumstances. Weight, activity level, how long you have been training for and what your goals are, all impact finding that sweet spot of consuming enough calories to maximise muscle growth but also lose body fat.
The leaner you are the harder it is to gain muscle and lose weight. Leaner individuals also tend to lose more lean mass in calorie deficits so could benefit from sticking to a lower calorie deficit range (100-300cal/day) to optimise muscle growth, whereas those with greater body fat could take advantage of the upper range of recommendations (300-500cal/day).
As muscle-building hormones respond to how large calorie deficits are, the smaller the calorie deficit the more optimal these hormones will respond, allowing greater muscle growth.
Basically, a smaller calorie deficit is going to make it easier for your body to build muscle, however, it will take longer to lose body fat. So, if your goals aren’t restricted by time, it makes sense to utilise a smaller calorie deficit (around 100-300) to maximise growth.
How Much Protein Should You Eat to Gain Muscle and Lose Weight?
The most important nutritional factor determining muscle gain is a high protein diet.
In a calorie deficit, a range of 2.3g/kg – 3.1g/kg of fat-free mass is optimal for muscle protein synthesis. The upper end should be utilised with larger calorie deficits to maximise muscle retention and increase fat loss.
Again, protein requirements for muscle building vary for individuals according to their body weight and how long they have been training. Novice and leaner athletes may benefit from the upper end.
Diet aside there are other factors influencing rates of muscle gain whilst in a calorie deficit.
- Body fat
- Resistance training experience
Older individuals have greater difficulty gaining muscle mass due to decreased muscle signaling pathways and women due to hormonal factors.
Individuals averaging less than the recommended 8 hours of sleep a night find it more difficult to lose body fat due to changes in hunger and stress hormones as well as decreases in exercise performance.
Experienced lifters also have slower rates of muscle growth and fat loss in comparison to their counterparts with less experience.
In a nutshell, achieving weight loss and muscle gain simultaneously will be easier to achieve if you are young, new to weight training, have a higher body fat percentage, have adequate sleep, and are a male.
The closer you are to your best potential physique, the harder it becomes to do both at the same time.
It is possible to achieve muscle gain and fat loss at the same time. But there is a reason this is not common practice among bodybuilders and within the competitive sports world.
It is certainly not the most efficient way of building muscle, however, if you’re not looking to maximise muscle growth and would like to achieve these two goals simultaneously it can be done in a lot of cases.