Can you gain muscle in a calorie deficit? Yes, here's how

When it comes to weight loss, most of us understand the basics: to lose weight, you need to burn more calories than you consume. This creates a calorie deficit, which is key to losing weight over time. But here’s the big question for women: Can you actually build muscle while in a calorie deficit?

Every woman’s fitness goals are unique. For many, it’s not just about the number on the scale but about a health change that feels healthy and sustainable in the long run.

If your goals include losing body fat while building muscle, it can often feel like walking a fine line.

While some claim it’s impossible to gain muscle on fewer calories, new research and strategies show that with the right approach, it’s doable. The secret lies in honing in on the details and making resistance training a priority.

By focusing on your nutrition, particularly ensuring enough protein intake, improving recovery with quality sleep, and gradually increasing the intensity of your strength workouts, you can achieve a balance that allows you to burn fat and build muscle simultaneously.

If you’re working on losing weight through a calorie deficit but also want to see muscle definition and strength gains, don’t stress — we’ve got all the tips and guidance you need to make it happen. Let’s break it down so you can start working toward both goals confidently.

What is a calorie deficit?

A calorie deficit happens when you’re taking in fewer calories than your body burns. But, you're not only burning calories during workouts — your body is working around the clock, burning calories to power everyday functions like breathing, digestion and even keeping your heart beating.

The number of calories you naturally burn in a day varies from person to person. It’s influenced by factors like your age, activity level, height, body composition, and yes, your sex.

For example, women generally require fewer daily calories than men. While the average man needs about 2,500 calories per day, the number for women will typically be lower, at around 2,000 per day [1].

Creating a calorie deficit means either eating fewer calories, upping your activity level, or a combination of both. Over time, this gradual deficit leads to weight loss.

Here’s a simple example to put it into perspective. If your body naturally burns around 2,000 calories a day but you only consume 1,500, you’ve created a 500-calorie deficit.

To figure out how many calories you need, you can use an online calorie intake calculator that factors in your unique body and lifestyle. Once you know this, you can plan your caloric deficit in a way that works for you. Keep in mind, this number isn’t universal. What works for one woman won’t necessarily work for another.

You don’t have to starve yourself or take extreme measures to achieve weight loss. A moderate 500-calorie deficit per day is enough to make progress without feeling constantly hungry or drained of energy [1].

Can you gain muscle in a calorie deficit?

For many women, it’s not just about losing weight — you also want to build strength and muscle. But gaining muscle while in a calorie deficit can feel like a complex puzzle, as it involves body recomposition.

Body recomposition is the process of losing fat and gaining muscle simultaneously. The aim is to improve the balance between muscle and fat in your body. The challenge is that fat loss requires a calorie deficit, while muscle growth typically thrives in a calorie surplus. But it is possible to gain muscle while in a calorie deficit.

To make body recomposition work, you need to focus on a slight to moderate calorie deficit. But it’s not just about reducing calories — what’s on your plate matters, as the balance of macronutrients (protein, carbs, and fats) plays an important role in achieving both goals.

The importance of protein intake to stimulate muscle growth

Research suggests that muscle growth is possible in a calorie deficit if you pay close attention to post-workout nutrition, especially your carbohydrate and protein intake.

For example, a 2016 study found that eating more protein than the usual dietary guidelines recommend can help preserve lean muscle mass even when consuming fewer calories [2]. During a 4-week trial, participants who followed a high-protein diet, resistance training, and high-intensity interval workouts were able to lose fat while building lean muscle.

The key takeaway? While a moderate calorie deficit can help with fat loss and muscle gain, drastically cutting calories could backfire.

Too few calories will sap your energy, making it harder to complete your workouts and recover properly, which are both essential for building muscle. It's a tough balance, but it is doable with the right routine.

How does building muscle work?

Building muscle, like weight loss, requires patience. It takes a while to see results when working on increasing lean mass, so try not to get discouraged if you don't see changes within weeks. The key to success with muscle growth is consistency.

Building muscle involves a process called hypertrophy — this is where your muscles experience stress (through exercise), break down and then repair themselves to be stronger than before. This stress occurs through resistance training, like lifting weights or bodyweight exercise, which results in tiny tears in your muscle fibres, triggering a process known as muscle protein synthesis.

For this process to work, your body needs to be fuelled and cared for, including consuming enough protein and essential nutrients while also getting enough rest.

If you're on a very low-calorie diet, your body may not have enough energy to support muscle growth. Initially, it may rely on stored energy, like glycogen and body fat, for fuel, but over time, it can begin breaking down muscle tissue for energy.

This is why it's so important to get enough protein and maintain a balanced diet to both preserve muscle mass and encourage further growth.

There are several health benefits associated with preserving and growing muscle mass, including positive impacts on your mental health as well as improving blood pressure and glycemic control. On the flip side, muscle loss can lead to health issues, including bone loss and fat gain [3].

How to lose fat and build muscle in a calorie deficit

While calorie surplus is generally recommended to gain muscle, it is possible to see muscle gains and weight loss at the same time.

By focusing on a few key factors, you can achieve both — here's how to do it.

Prioritise your protein intake

Protein is incredibly important to help both build and repair muscle tissue. While you're aiming to achieve a calorie deficit, you can still prioritise your protein intake, especially following strength workouts.

Research by the US Army Research Institute of Environmental Medicine, participants who consumed a reduced-calorie diet where they reduced their calories by 40%, while exercising daily and eating twice the recommended daily amount of protein lost just as much weight as those who ate the same amount of calories but less protein [4].

However, the high-protein participants lose more fat and maintained more muscle than those ate less than the recommended daily amount of protein. So, protein is integral to weight loss and muscle gain!

While your recommended daily protein intake will differ based on factors like age, weight and activity level, you should aim for around 1 gram of protein per kilogram of body weight to help maximise your muscle growth.

Eat your carbs before exercise

To get the most out of your workouts, it's recommended you eat carbohydrates before exercising. Carbs often get a bad reputation in the world of weight loss but they play an essential role in muscle building, helping to increase energy levels for working out.

Carbohydrates are also important for recovery, helping you build as much lean muscle as possible. Timing is important when it comes to eating carbs and that's why eating them before exercise is ideal. This helps ensure your glycogen levels stay high, helping to avoid fatigue.

Gradually increase weights

To build muscle, you need to needs to go through the process we mentioned earlier, called muscle hypertrophy. This occurs when you continually challenge your body by gradually increasing the weights you use, which helps your body become stronger as you adapt to the resistance.

By increasing the intensity with heavier weights, you also apply progressive overload on your muscles, which also encourages them to grow.

A 2011 study analysed 83 people over 12 weeks as they engaged in arm strengthening exercises. Both women and men who gradually increased the weights they used and the numbers of reps they performed saw significant improvements in both bicep strength and muscle growth [5].

The takeaway? Consistently pushing your limits with heavier weights not only builds strength but also helps you see the muscle gains you’re working toward.

Get lots of sleep

Alongside nutrition and exercise, sleep is essential for muscle protein synthesis, as this is where your muscle tissue repairs and rebuilds after an intense workout.

The average adult needs around 7-9 hours of sleep every night, and this plays a significant role in muscle growth and fat loss [6]. A 2010 study split participants into 2 groups: the first sleeping 8.5 hours a night and the second sleeping only 5.5 hours.

Both groups followed a calorie deficit for the 2 weeks, and researchers found that although the participants lost the same amount of weight, those in the group getting less sleep lost 60% more muscle while the other group preserved it.

This highlights just how important sleep and rest if for your fitness routine.

What foods should you eat to gain muscle and lose weight?

As we mentioned earlier, protein is your best friend for helping build muscle mass. Plus, it also a relatively high thermic effect when compared to carbs and fats, making it good for weight loss too.

The thermic effect of food (TEF) refers to the increase in energy expenditure that occurs when digesting, absorbing and metabolising the nutrients. Around 20-30% of the calories in protein are expended during digestion and metabolic reactions.

This means that protein helps to increase the fat-burning process by increasing your metabolism, positively impacting your weight loss efforts.

These are the foods you want to reach for to encourage this process:

• Lean meats like chicken, turkey, and lean beef
• Fish and seafood like salmon and tuna
• Eggs 
• Dairy products like Greek yoghurt and cottage cheese
• Plant-based protein sources like tofu, tempeh and legumes 
• Whole grains like brown rice, quinoa and oats
• Sweet potatoes 
• Fruits and veggies 
• Nuts and seeds

Gaining muscle in a calorie deficit: Next steps

Sticking to a moderate caloric deficit means that you'll still have the energy to work out and engage in strength training, which will encourage both weight loss and muscle growth.

Focusing on high-protein foods, timing when you eat carbs, getting lots of rest and gradually increasing the weights you use will help you achieve body recomposition. However, if you'd like personalised guidance on your weight loss journey, you might like to consider Juniper.

Our Weight Reset Program helps you understand your unique nutritional and physical needs, so you can build healthy habits that last.

Get treatment that targets weight gain on a biological level, plus a dietitian-led program that supports long-term weight maintenance.

We help you make the lifestyle changes that help you not only lose weight but keep it off through health coaching around nutrition, movement, stress, sleep and 1-on-1 health tracking to measure your biometric health and check in on your goals.