To lose fat, you need to eat in a calorie deficit. The best way to build muscle, however, is by eating in a calorie surplus while training.

Trying to achieve both at once - known as body recomposition - is challenging, but not impossible.

Unless you're new to strength training, the likelihood is that you'll lose some muscle while also losing fat, personal trainer and transformation coach Jono Castano told Insider.

However, it's possible to maintain muscle while losing fat, lowering your body fat percentage, if you avoid some common pitfalls.

Dropping your calories too low

If you eat too little, not only will it be harder to stick to your diet while your workouts suffer due to lack of energy, but your body will burn muscle as well as fat.

"You're likely to lose muscle tissue, feel run down, and potentially fall off the bandwagon," personal trainer Emily Servante previously told Insider.

Castano advises paying particular attention to how you eat before and after training.

"Eat more calories around your workouts to fuel and refuel," Castano said. "This way your muscles aren't deprived and can grow."

Not eating enough protein

Studies show that following a high-protein diet can help maintain muscle and boost metabolism, keep you feeling full when trying to lose weight, and reduce hunger.

Experts recommend aiming for 1.6-2.2 grams of protein per kilogram of body weight, and if you don't eat enough you may find it harder to reach your goals.

Carbs and fat are less crucial, but ensure you're eating enough of each to fuel your workouts and make you feel good.

"Diet is everything," Castano said. "Including the right macronutrients is what is going to really change your gains."

Not strength training

Lift weights regularly, with progressive overload, to send a signal to your body that your muscle is being used and should be held on to.

"Retaining lean tissue [muscle] whilst in the calorie deficit needed to reduce body fat will require regular strength (resistance) training," Luke Worthington previously told Insider. "Lean tissue is very much a 'use it or lose it' commodity."

Castano advises paying attention to technique and tempo as well as weight.

"You want to make sure the weight is challenging enough to stimulate muscle growth," he said.

Doing too much cardio

Cardio doesn't necessarily hinder muscle growth and maintenance, but it can slow your progress if it comes at the expense of resistance training or makes you hungrier and thus go out of your calorie deficit.

Castano advises limiting high intensity cardio.

"When doing cardio you want to keep your heart rate under 120 bpm, otherwise it can burn into muscle," he said. "Going for power walks rather than more intense cardio is what I suggest."

Not resting enough

Muscles don't grow in the gym, they grow when we sleep.

Resting adequately is crucial for both fat loss and muscle gain, and if you don't give your body enough time to recover, you'll find it harder to reach your goals.

"We usually think smashing it out is going to get the best results but with growing muscle, that's not the case," Castano said. "Your weekly training program should separate out different muscle groups so you can rest them in between."

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