Instant overview
To lose fat and gain muscle at the same time, you need a moderate calorie deficit — not an extreme one. Start by cutting just 200-300 calories from your maintenance level and adjust gradually. - A high-protein diet is essential. It helps maintain muscle mass during a deficit, keeps you feeling fuller for longer and reduces cravings for higher-calorie snacks.
- Healthy fats — especially omega-3 fatty acids from oily fish, flaxseeds and chia seeds — support hormone production and have been linked to both muscle gain and fat reduction.
- Strength training with compound exercises like squats, deadlifts and bench presses at least two to three times a week is the most effective way to burn calories while building muscle.
To lose fat and gain muscle at the same time, you need to create a moderate calorie deficit while eating enough protein and healthy fats to support muscle repair and growth. Combine this with a regular strength training programme focused on compound exercises, make sure you're getting enough vitamin D, and give your body proper rest days to recover.
Lose fat, gain muscle: at a glance
| Strategy | What to do | Why it matters |
|---|---|---|
| Calorie deficit | Cut 200-300 calories from maintenance, adjust gradually | Too extreme a deficit burns muscle as well as fat |
| Protein intake | Fill your plate with fish, lean meat, eggs, tofu, beans and dairy | Maintains lean body mass and keeps you feeling full |
| Healthy fats | Focus on omega-3 sources like salmon, chia seeds and flaxseeds | Supports hormone production including testosterone for muscle growth |
| Vitamin D | Get from oily fish, egg yolks, fortified foods or supplements | A lack of vitamin D is linked to reduced muscle repair and lean mass loss |
| Strength training | Compound exercises 2-3 times per week with rest days | Burns more calories while challenging multiple muscle groups at once |
Jump to:
- How to build muscle and lose fat
- 1. Eat healthy fats
- 2. Follow a high-protein diet
- 3. Don't make your calorie deficit too extreme
- 4. Get a dose of vitamin D
- 5. Do strength training
- Lose fat, gain muscle: at a glance
- Take home message
- Frequently asked questions
How to build muscle and lose fat
1. Eat healthy fats
Hold off on that huge scoop of full-fat ice cream — it's the healthy fats we're after here. Dietary fat is really useful for gaining muscle as it can help you boost your energy intake and provide extra fuel for those tougher workouts. They also help promote the production of hormones in our bodies, including testosterone which can help increase muscle mass.
Before you grab the chocolate spread or add more butter to your toast in the morning, opt for some omega-3s instead. This way, you'll be able to lose fat and gain muscle at the same time.
Omega-3 fatty acids are fats found in oily fish, olive oil, and nuts. They have many purposes including improved heart health and muscle gain. In fact, it's been found that supplementing omega-3 fatty acid for six weeks resulted in a 0.5kg gain in muscle and 0.5kg reduction in fat mass.
- Salmon
- Tuna
- Mackerel
- Sardines
- Chia seeds
- Flaxseeds
- Canola oil
Learn more about all the benefits of fish oil like improved vision and cognition here...
2. Follow a high-protein diet
It's all too obvious — if you want to build muscle, you need to eat more protein, of course. Muscles require protein for their growth and repair. So, fill your plate with fish, lean meat, eggs, tofu, beans and pulses, and low-fat dairy. A lot of low-calorie diets result in a low intake of protein which can result in poor growth and loss of muscle mass, even if you're shifting the fat.
Increasing your protein intake can be helpful to minimise the loss of lean body mass. Out of a group of young, healthy, elite athletes, those given a high-protein diet lost more weight while still maintaining muscle in comparison to those with a normal amount of protein in their diets.
Protein also takes longer than carbs to digest, so it can keep you feeling fuller for longer. When you're satisfied thanks to higher protein intake, you're less likely to crave higher-calorie snacks and extra fats and carbs. Reducing overall calorie intake by limiting fat and excess carbs can help you lose fat and gain muscle.
- Greek yoghurt and other dairy products
- Chicken breast
- Turkey breast
- Cottage cheese
- Quinoa
- Chickpeas
- Milk
- Almonds
Start hitting your protein target early with these high-protein breakfasts...
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3. Don't make your calorie deficit too extreme
Want a sure-fire way to misery and likely a bit of a binge? Try eating practically nothing. Extremely restricting your calorie intake for weight loss is not beneficial to your weight loss, despite what you might have once thought. The drastic weight loss you experience is more likely to be due to losing water and muscle rather than fat.
It's clear that very low-calorie diets lead to a large initial drop in total weight loss, especially lean body mass (muscle) as your body will be using everything it can to make energy, including your juicy biceps. Very low-calorie diets aren't sustainable in the long run. Have a bit of patience and gradually reduce your calories so you can keep the muscle, and your happiness.
In order to maintain as much muscle as possible while losing fat, start off by taking off anywhere between 200-300 calories from what you're estimated for maintenance daily and gradually adjust according to how fast you're losing weight.
Calculate a healthy calorie deficit for yourself with these three steps...
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4. Get a dose of vitamin D
Spending all your time between the office and the gym means you probably aren't soaking up too many rays of sunshine.
Vitamin D is responsible for the absorption of various minerals including calcium, magnesium, phosphate and other biological effects important in our body. This makes vitamin D one of the most important vitamins for building muscle and losing fat. If your diet is low in vitamin D, it could be preventing you from reducing fat and building muscle.
A lack of vitamin D has been associated with lowered muscle repair and increased loss of lean body mass. There's still more research needed into the efficacy of vitamin D supplementation as a powerful stimulator for muscle growth, but the results look promising. So, unless you're exercising somewhere sunny every day (lucky you!), get some more vitamin D in your system.
- Tuna
- Mackerel
- Salmon
- Egg yolks
- Cheese
- Fortified foods, eg soya milk and cereals
If you're living in the UK, chances are you're not getting nearly enough sunlight (it rains far too much here for that). As the sun is our main source of vitamin D, you may want to take a supplement to boost your intake. Some of us need more than others, so check with your doctor for the best advice. And if you are heading out into the sunshine, remember to always wear sunscreen!
5. Do strength training
Obviously to build those guns, you're going to have to lift some weights. The best way to burn calories, as well as build muscle, is to add a good strength training programme into your routine.
You want to focus on working your whole body at least two times a week — easy enough, right? Aim for exercises that work more than one muscle group at a time. For example, squats, bench presses, deadlifts, overhead presses and barbell rows are great.
Compound movements (which target more than one muscle group) boost calorie burn while challenging your muscles. They require more energy (calorie burn) to accomplish and are the best way to target fat loss and muscle building at the same time. This will make it easier for you to lift heavier, get stronger, or maintain muscle as you lose weight.
Try to aim for two to three gym sessions with a variety of compound exercises like squats and deadlifts. And don't forget to have at least one rest day a week to give enough time for your body to recover and prevent any possible injuries. Check out our 6 top recovery supplements to help you on your way.
Take home message
To lose weight and build muscle, you need to focus on having a calorie deficit while still providing enough nutrition to help promote muscle gains. Think about the levels of protein, fats, and vitamin D in your diet and combine this with a good strength training programme with enough rest days. This will ensure you maintain as much muscle as possible as you continue on your fat loss journey.
Frequently asked questions
Can you lose fat and gain muscle at the same time?
Yes, but it takes patience. You need a moderate calorie deficit combined with high protein intake and regular strength training. Unless you're brand new to training or coming back from a long break, it's a slow process — but it is possible if you get the balance right.
How big should my calorie deficit be if I want to keep muscle?
Start by cutting 200-300 calories from your daily maintenance level. Going too extreme will cause your body to burn muscle as well as fat, and very low-calorie diets tend to result in a large drop in lean body mass. Adjust gradually every couple of weeks based on how your body is responding.
Why is protein important for losing fat and building muscle?
Protein is essential for muscle growth and repair. A high-protein diet helps minimise the loss of lean body mass during a calorie deficit, and it also keeps you feeling fuller for longer — meaning you're less likely to reach for higher-calorie snacks. Fill your plate with fish, lean meat, eggs, beans and low-fat dairy.
Do I need to take vitamin D supplements to build muscle?
Not necessarily, but if you're not getting enough sunlight — which is common in the UK — it's worth considering. A lack of vitamin D has been linked to reduced muscle repair and loss of lean body mass. You can get vitamin D from oily fish, egg yolks and fortified foods, or take a supplement after checking with your doctor.
Does this advice apply to people on GLP-1 medications?
Yes. The core principles here — eating enough protein, including healthy fats, keeping your calorie deficit moderate rather than extreme, and doing regular strength training — apply whether you're on GLP-1 medications or not.
The goal is the same: lose fat while holding on to as much muscle as possible. If you're taking any medication, it's always worth checking in with your doctor to make sure your nutrition and training plan works alongside your treatment.
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