You’ve been working out consistently and your weight hasn’t moved much – is your hard work paying off? 

It can be tough to assess objectively whether you’re gaining muscle. It’s common to keep track of your weight while working out, but weight isn’t the most accurate metric for measuring muscle gain or fat loss. 

Understanding how muscle gain works and noting some signs of muscle gain can give you a better sense of how you’re progressing. Want more accuracy? A DEXA scan is the best way to accurately assess your changing body composition. 

Let’s dive into the science of muscle gain!

The science of muscle gain


An athletic woman completes a heavy deadlift with a barbell in a gym with low lighting.

How does muscle gain work?

Muscle gain (muscle hypertrophy) has two key conditions: 

  1. Weight-bearing exercise
  2. A caloric surplus 

Consistent, challenging strength training damages muscle fibres. The caloric surplus provides your body with the fuel it needs to repair these fibres – creating larger, stronger muscles in the process. Adequate protein intake as a part of the caloric surplus is also key; without this, muscle loss can occur. 

While optimising muscle gain is a little more complex than this, the popular generalisation stands true: lift heavy, eat more. To get an idea of the types of strength exercises you should incorporate into your routine to start building muscle, check out our guide to body composition exercises

How does fat loss work? 

While fat loss is often thought of as complicated, it only has one main condition: 

  1. A caloric deficit

This means that for fat loss (or any weight loss) to occur, you need to consume fewer calories than you expend. This can be achieved through a combination of diet and exercise, or from diet alone. Understanding the number of calories your body requires to function daily (your TDEE) is essential to maintaining a calorie deficit. 

Calorie deficit not working? These common calorie deficit culprits could be behind your stalled weight loss. 

How do I know if I’m gaining muscle or fat?

Fat and muscle are fundamentally different tissues, but it can be difficult to assess which is behind your weight gain with only the number on the scale to go by. 

The signs of muscle gain below can be a good starting place for assessing the source of your weight gain. In general, weight gain from fat will result in a softer appearance, while weight gain from muscle will leave you looking leaner and feeling stronger. 

The most accurate way to assess any change in your body composition is through body composition testing. A DEXA scan for body composition can accurately measure your lean mass, fat mass, visceral fat, and more, eliminating any guesswork. Monitoring your body composition can be a great way to ensure you’re maintaining a healthy body fat percentage as you prioritise muscle gain.

How long does it take to build muscle?

How long it takes to build muscle will depend on where you’re starting from. 

If you’re a beginner or relatively new to working out, you can expect to see signs of muscle growth within the first 8 weeks of hitting the gym – assuming you’re doing so consistently. For more experienced gym-goers, you may notice you gain muscle at a quicker rate. However, if you’ve kept the same routine for a long time, it’s possible to experience a plateau in your gains. 

While it takes time to see noticeable muscle growth, strength training is cumulative, and every workout contributes to your progress. Even before you notice any change in muscle size, a host of other benefits – from boosted protein synthesis in the hours following your workout to improved muscle awareness – happen far more quickly. 

How quickly you gain muscle depends on a variety of factors, from your genetic and hormonal makeup to your age, gender, and ratio of fast to slow muscle twitch fibres. Be consistent, and don’t be discouraged if you don’t see visible changes right away –  make sure to check the signs below for other indicators of muscle gain. 

How do I gain muscle and lose fat? 

This is a larger topic than we’ll be getting into in this blog!

For more information on gaining muscle, you can check out our guide to building lean muscle mass. Looking to lose fat? Check out our guide to fat loss.

For other common body composition FAQs such as whether you can gain muscle and lose fat at the same time, check out our body comp guide

Top signs of gaining muscle (and losing fat)

A mature woman in green workout clothing holds a yoga mat and water bottle under her left arm while flexing her right bicep, smiling.

Let’s take a look at the top signs of muscle gain. Many of these can also be signs of fat loss — provided you prioritise maintaining muscle mass as you cut. 

You feel stronger 

It might sound obvious, but one of the clearest signs of muscle gain is that you feel stronger and more capable – inside of the gym and out. Keeping a note of your workout routine – including weights, reps, and times – can be an easy way to track your progress. If you’re noticing consistent improvements here, there’s a good chance you’re succeeding at gaining muscle. This can be one of the most satisfying parts of strength training, so make sure to soak it up!

You look leaner 

It’s common for your weight to increase as you build muscle. This can feel discouraging – particularly if you’re simultaneously targeting fat loss – but is a normal part of building muscle.

If you’re concerned about whether your weight gain is muscle or fat, you’re not alone. One of the easiest ways to assess this as home is visually. If you’ve taken before and after pictures, comparing these can prove more objective than relying on memory. Similarly, you may notice increased muscle definition, less softness, and an overall leaner physique. 

Checking in on how your clothes fit can be another useful rule of thumb. Since muscle is denser than fat, if you’ve gained weight but your clothes fit a little looser, that’s a good sign you may have gained muscle. 

Your measurements have changed

While perceptions of our bodies can be flawed, measurements provide a more objective method of checking in on body composition changes. 

Different measurements can shed insight into different types of body composition changes. For example, while an increased weight measurement might be indicative of fat gain, increased measurements in your biceps, upper thighs, or chest might be a sign of increased muscle in these areas. Similarly, decreased measurements at your waist or hips could be a sign of fat loss.

While measurements aren’t an infallible method of assessing your body composition, they’re accessible and easily done at home, allowing you to check in more frequently than you could with advanced testing such as a DEXA scan.  

Your workouts are getting easier 

Whether you can lift heavier, complete more reps, or complete your workout in less time, your workouts feeling easier is a sign of increased strength and power. Progressive overload – a steady increase in your weight, reps, or both – is a tried and tested way of continuously challenging yourself in your strength workouts. This helps to avoid a plateau and maximise your gains. 

Increased muscle mass can also benefit your endurance, helping cardio workouts and daily activities feel easier and less tiring. If you’re noticing any of these, you’re on the right track – keep it up. 

You have more energy 

A less-emphasised benefit of gaining muscle is the accompanying increase in energy.

Increased muscle mass is linked to improved energy levels, lower stress, and even a stronger immune system. The benefits of building muscle and improving your body composition are extensive – we’ve listed some of the top muscle-building benefits here.  

This boost in energy can make it easier to find the energy to work out, leading to further gains – and also be beneficial across other areas of your life.

Your metabolism has increased

Increased muscle mass is also linked to an increased energy expenditure – a faster metabolic rate. This means the number of calories you burn from simply existing (your basal metabolic rate, or BMR) can increase as you build muscle. 

If your metabolic rate has increased, you might find yourself feeling more hungry, needing more food throughout the day, or finding it easier to maintain or even lose weight. To work out or recalculate your BMR and assess your caloric needs, you can use our custom BMR & TDEE calculator. 

Your recovery time has decreased 

Another sign (and benefit) of muscle gain is that your recovery time may decrease. 

For many beginners, post-workout fatigue, aches, and even injuries can prove discouraging and affect adherence to a new program. Luckily, with consistent training, recovery time starts to decrease. 

As you work towards gaining muscle, your body needs time to rest and repair. Scheduling rest days for recovery time is crucial to providing your body with the time (and fuel) it needs to build and repair muscle fibres and facilitate muscle growth. How long it takes your body to recover depends on a variety of factors, including: 

  • How long you’ve been training
  • How well (and long) you sleep
  • Your stress levels
  • The volume, intensity, and duration of your training

Alternating muscle groups in your workouts, scheduling regular rest days, and getting enough water and protein can all help speed up your workout recovery. 

Accurately measure your muscle gain and fat loss

A multiracial team of 4 personal trainers in blue gym clothes smile with their arms crossed.

Hopefully, these signs of muscle gain and fat loss have given you a sense of where you’re at on your fitness journey. 

If you’re looking for a more accurate overview of your body composition, then a DEXA scan for body composition is the best place to start. My Vital Metrics offers data-rich insights based on the gold standard in body composition technology, equipping you to take your muscle gain to the next level.  

To find out more or to book your free fitness & nutrition consultation, reach out to My Vital Metrics today!