Why you’re gaining muscle but not losing fat – 6 common mistakes and how to correct them
More energy, improved strength and increased muscle mass are all positive signs your gym routine is paying off. But if fat loss is your goal, not seeing changes there can feel frustrating – especially when you’re putting in the work.
It’s something strength coach and dietitian Denvyr Tyler sees often. But she’s quick to point out that fat loss and weight loss aren’t the same thing. ‘Weight loss can include reductions in muscle, water and even bone mass,’ she explains. In other words, the number on the scale doesn’t tell you what’s actually changing in your body.
Focusing solely on weight loss can also backfire. ‘It can make you feel stressed, slow your metabolism and even affect your hunger and fullness hormones,’ she says.
Instead, Tyler encourages focusing on sustainable habits that support both muscle and fat loss over time.
6 reasons you might be building muscle without losing fat
1. More cardio is making you hungrier
Adding cardio on top of strength training can increase your appetite, says Tyler – which may lead you to eat more than you realise.
For fat loss to occur, you typically need to be in a small energy deficit – using slightly more energy than you consume over time. If increased hunger cancels that out, progress can stall.
‘I usually recommend one – max three – days of cardio alongside strength training,’ she says. ‘If you’re doing lots of running or high-intensity sessions, your body may simply be trying to keep up and ensure you’re eating enough to recover.’
That said, cardio still plays an important role in overall health. The key is balance – not relying on it as your only tool for fat loss.
Muscle plays a central role in body recomposition. ‘It helps you feel stronger, fitter and more capable,’ says Tyler.
To keep building it, your training needs to gradually become more challenging – whether that’s increasing weight, reps or frequency. This is known as progressive overload.
When you train, you place stress on your muscles. Your body adapts by repairing and strengthening them so they can handle that stress more easily next time. Without increasing the challenge, your body has no reason to keep adapting.
Building muscle can support fat loss indirectly. It increases the amount of energy your body uses during recovery and helps improve how your body stores and uses fuel.
‘If you’re doing the same workouts with the same weights week after week, your progress will eventually stall,’ Tyler says. A structured programme that evolves over time is key.
3. You’re too sedentary outside the gym
If you spend most of your day sitting – at a desk, for example – your overall movement levels may be lower than you think.
This is where NEAT (non-exercise activity thermogenesis) comes in. It includes all the movement you do outside of formal workouts – walking, doing chores, climbing stairs or even fidgeting.
NEAT can make up a large portion of your total daily energy expenditure (TDEE), often more than structured exercise. Increasing it can help support fat loss by gently raising how much energy you use across the day.
‘You don’t have to do it all at once,’ says Tyler. ‘Even short walks – 10 minutes in the morning, after lunch or in the evening – can add up.’
4. You’re expecting results too quickly
Body recomposition takes time. ‘Try to think in three-month blocks,’ says Tyler. ‘That gives you enough time to build habits, see progress and stay motivated.’
Research supports this. Studies have shown that meaningful changes in body composition – such as reduced fat mass and increased lean mass – typically occur over 8-12 weeks or longer.
The key is consistency. Progress isn’t always linear, but small, repeated actions over time are what drive results.
5. You’re unintentionally eating in a surplus
If you’re consuming more energy than your body needs, fat loss is unlikely – even if you’re training regularly.
This can happen for a few reasons. Increased training can boost hunger, and poor sleep can make things worse.
‘Sleep is huge,’ says Tyler. ‘Aim for at least seven hours where possible. If you’re getting less than six and training hard, your cravings can increase and recovery will suffer.’
If consistent sleep isn’t realistic – for example, for new parents or shift workers – focus on what you can control. Short naps, a cool and dark sleep environment, and consistent wind-down routines can all help support recovery and energy levels.
6. You’re not paying attention to your macros
Even if your overall calorie intake is in check, your macronutrient balance matters – especially when it comes to protein.
Protein supports muscle repair and growth, and can help keep you fuller for longer.
‘A higher-protein diet is consistently linked with better body composition outcomes,’ says Tyler.
She recommends aiming for at least 100g per day as a starting point, adjusting based on body size and activity levels. A common guideline is around 1.6-2.2g per kg of body weight.
A simple way to approach it: build your meals around a protein source, then add carbohydrates and fats to round things out.
The bottom line
Building muscle without losing fat doesn’t mean you’re doing something wrong. It often comes down to consistency, balance and time.
Rather than chasing rapid changes, focus on habits that support long-term progress – strength training, enough protein, daily movement and adequate rest.
That’s what ultimately drives sustainable body recomposition.
Having a strong core is about far more than sporting a six-pack. Build functional mid-section strength – while also improving your power, posture, coordination and balance – with WH COLLECTIVE coach Izy George’s 4-week core challenge. Download the Women’s Health UK app to access the full training plan today.
Get the app
