The Holy Grail of building muscle mass and losing fat simultaneously is all too often an elusive target for those looking to sculpt their physique. In the quest for gains in muscle mass and strength, ab definition often fades and everything begins to look a little bit, well, ‘softer’.

After all, you’ve got to eat more calories to gain more muscle, but less calories to lose fat… right?

In fact, past research has found that having a diet that’s in a calorie-deficit usually results in around 20-30% of mass lost as muscle mass, and the rest as fat.

The ‘build muscle, lose fat’ debate has been under scrutiny for decades, but here’s the good news: there has just been a new scientific development in the world of diet and exercise physiology.

Scientists have discovered that it’s possible to achieve both muscle gain and fat loss at the same time, and quickly, too.

The research, which was published in the American Journal of Clinical Nutrition1, assigned 40 young men to two different diets.

Both groups of men ate around 40% less calories compared with their usual requirements, but one group consumed more protein than the other.

The first group consumed a higher-protein, medium-carbohydrate, low-fat diet (35% protein, 50% carbohydrates, 15% fat), which translates to 2.4g of protein per kg of bodyweight per day.

The second group consumed a lower-protein, medium-carbohydrate, medium-fat diet (15% protein, 50% carbohydrates, 35% fat), which translates to 1.2g of protein per kg of bodyweight per day.

Thomas Longland, lead author of the research, and his colleagues chose to lower the fat in the higher-protein group to cut calories from the men’s diets, as they acknowledged that lowering carbohydrates would have had an impact on exercise performance.

Both groups performed a combination of resistance exercise training and high-intensity interval training (HIIT) six times per week.

During the four weeks, the higher-protein group gained muscle mass (around 2.5lb on average), while the lower protein group didn’t gain any muscle – despite still eating above the government’s recommendations for protein, which is 0.75g of protein per kg of bodyweight per day.

Something unexpected also happened in the higher-protein group, which the researchers said they were intrigued by.

As well as gaining muscle mass, the higher-protein group also lost significantly more body fat than the lower-protein group. In fact, fat was the sole contributor to the participants’ weight loss.

The researchers proposed that, as well as being in a calorie-deficit, HIIT contributed to the increased fat loss seen in both groups, as studies have shown that 20 minutes of HIIT increases lipolysis (fat burning). However, they’re unsure why the higher-protein group lost more fat, as the groups’ calorie-intake was identical.

The lower-protein group at least didn’t lose any muscle mass, which is normally a consequence of just cutting calories and not working out at all.

Thomas and his team say they’d expect to see similar results to this study in women, and they hope to conduct a similar study soon with a female group, too.

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1. Longland, T. M., Oikawa, S. Y., Mitchell, C. J., Devries, M. C., & Phillips, S. M. (2016). 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. The American Journal of Clinical Nutrition, 103(3), 738-746.

Jennifer Blow

Editor & Qualified Nutritionist