Diet vs exercise: which is more important for health?

Deciding what’s more important between diet and exercise is an age-old debate. You may have a friend who is convinced that doing sport is way more important to their health than what they eat. Maybe another friend says a nutritious meal brings them far more joy than a gym session ever could. Who are we to question these feelings?

The problem is that the ‘diet vs exercise’ question can mean many different things. Better for what? For managing weight? For sleeping well? For having new experiences and meeting people? You see, the question is not as clear-cut as it first seems and depends on your goals. 

It also depends on your starting point. If you already eat well, adding regular movement could bring the biggest boost to your wellbeing. On the other hand, if you’re always at the gym, then tweaking your diet could be the key to getting more from your workouts. 

That being said, the diet vs exercise question is still worth exploring because they do provide different benefits. Let’s dive in.

Why diet often matters more for weight loss

“You can’t outrun a poor diet”. There is wisdom in this phrase. If we strip it back to basics, food is just energy. In fact, the number of calories in your meal is referring literally to the amount of energy it contains. We digest this food and use this energy as our power source. This process, known as our metabolism, happens throughout our bodies and involves many organs. 

Simply being alive burns a surprising number of calories. Even on a day when you do nothing at all you will burn 1,300 to more than 2,000 calories, depending on your age, body size and gender.² We need energy to breathe, keep blood flowing, grow and repair cells, and many other functions in our bodies. 

If you eat more than the recommended amount, you can burn some of the extra calories through exercise. But if you regularly eat extra calories, it starts to add up. It can take a lot of work to balance things out. For example, a typical double cheeseburger on European high streets could easily have 500 calories.³ To burn this off, you would need to do:  

• around 40 minutes of moderate running
• 75 minutes of moderate swimming
• more than 2 hours of pilates⁴

Now imagine adding a portion of French fries (around 300 calories) and a doughnut (at least 200 calories). Now you have to do 80 minutes of running, swim for 2.5 hours, or do yoga for 4 hours. You can see how it quickly adds up.

However, this is where exercise can provide long-term benefits. Gaining muscle can improve your metabolism – helping you to burn off the calories more efficiently. But the effect is relatively modest.⁵ You can only run, lift, or cycle off so many chocolate cakes before you start to lose the contest. Therefore, a balanced diet combined with regular movement is best.

Physical activity is great for you in many other ways

Often we think about exercise in terms of weight loss, or getting in shape before a beach holiday. But exercise is fantastic for you in so many other ways. Studies show that exercise can improve brain health, reduce fat levels in blood, and even support the health of individual cells in our bodies.⁶ All of these things can help prevent and manage chronic diseases such as cardiovascular conditions, cancer and diabetes.⁷ 

Movement doesn’t just work on the body – it supports the mind, too. Even a short burst of activity can lift your mood, helping your brain release feel-good chemicals like dopamine and serotonin. Those natural boosts can ease stress in the moment and can reduce symptoms of depression and anxiety. Regular exercise also enhances brain health and can improve overall wellbeing whatever your situation.⁷

What is exercise, anyway?

Think of exercise as a planned and structured form of physical activity – something you choose to do because it helps your body stay strong, capable and energised.⁸ Find exercises you enjoy. It doesn’t have to mean gyms or gadgets; anything that gets your heart rate up or challenges your muscles can count. 

There are two main types of exercise we need, and many sports combine elements of both.

1. Cardio (aerobic exercise)

These are activities that make you breathe a little faster and warm up your muscles. 

Benefits: Cardio supports your heart, lungs and circulation, helping reduce the risk of cardiovascular disease and building endurance.

Examples: running, brisk walking, cycling, swimming and dance classes.

2. Strength training

Strength-focused activities work your muscles against resistance – this could be your own bodyweight, resistance bands, or weights. 

Benefits: Keeping muscles strong helps you stay steady on your feet, protect your bones, and manage everyday tasks. Maintaining strength is especially important as we get older. Even simple movements like lifting shopping bags or standing up from a chair rely on muscle strength.

Examples: Lifting weights, pilates, resistance bands, body weight exercises (push-ups, pull-ups, planks, etc), or give breakdancing a try! 

How food and movement work together

Eating well and exercising are not just two separate things you need to make time for in your calendar. They can work in partnership. Here’s what you should eat before, during and after exercise.

Before = carbohydrates, your top fuel

Carbohydrates – like pasta, rice and bread – are your body’s preferred energy source. You break them down into glucose, which fuels your muscles and brain. Whatever you don’t need right away is stored as glycogen, your “ready-to-use” fuel tank.

A carb-rich meal or snack a few hours before movement helps top up those stores: pasta, rice, potatoes, whole-grain bread, oatmeal, fruit. Starting exercise with full glycogen means more energy and less early fatigue.

Learn more in our guide to carbs.

During = easily digestible carbs, but usually nothing is needed

Most movement under an hour doesn’t usually need extra fuel, your glycogen stores usually have you covered.

For longer or tougher sessions (think long runs, long rides, or high-intensity work over 60 minutes), a small top-up of easy-to-digest carbs can help. Examples: a banana, a few sips of sports drink, or an energy gel when chewing isn’t practical.

After = protein (plus some carbs)

After exercise, your body switches to repair mode. Protein provides the amino acids needed to rebuild and strengthen muscle. Aim for lean sources: chicken, fish, tofu, beans or yoghurt.

Including some carbs alongside protein helps you refill glycogen – useful if you train again soon.

Learn more in our guide to protein.

Remember to stay hydrated

Staying hydrated will keep you safe, give you energy, and help recovery. For most sessions, water is enough. If you’re sweating heavily, training for a long time or exercising in heat, you may also need to replace the salty minerals in your body called electrolytes. We lose some of these when we sweat, explaining why it tastes a bit salty. 

Electrolytes help your cells and tissues hold on to water, keeping everything running smoothly. Foods rich in electrolytes include bananas, nuts and seeds. But if you’re mid-activity it might be more convenient to get them from sports drinks.

Learn more in our guide to hydration.

Diet vs exercise: which matters more as we age?

We just looked at how food can support exercise. But what about the longer view? Is it diet or physical activity that protects our health more as we age?

If you were hoping for a clear winner… again we’re sorry to disappoint. When it comes to long-term, healthy ageing, again it’s the combination of both that really holds the key. Here are five areas where food and exercise work best as a team.

1. Heart health: whole foods + cardio

A diet rich in whole foods can help support healthy cholesterol and reduce inflammation, while cardio-based activities keep your heart and blood vessels strong. Great options include fruit and vegetables, nuts, seeds, fish and lean meats. Together, they help maintain healthy blood pressure, support circulation and reduce strain on your cardiovascular system as you age.

2. Cognitive abilities: brain nutrition + movement

Certain nutrients – including omega-3 fats, antioxidants and B vitamins – help your brain communicate and repair itself. Great options include salmon, walnuts and leafy greens like spinach and kale. Exercise complements this by boosting blood flow to the brain and supporting neuroplasticity, the process that helps you learn, adapt and stay mentally sharp.

3. Slowing ageing: antioxidants + strength training

Antioxidant-rich foods help counter oxidative stress, a natural process that contributes to cellular ageing. Common examples include tomatoes, sweet potatoes, green and black tea, as well as spices like turmeric and cinnamon. Strength training adds another layer of protection by preserving muscle, mobility and metabolic function – key ingredients for staying independent and active later in life.6

4. Mental health: mood chemistry + movement

Again, aim for a diet rich in whole foods if possible, which can support brain health. Try to limit ultra-processed foods – such as packaged products high in sugar, salt and preservatives.¹⁰ Movement adds its own lift, releasing feel-good chemicals and helping regulate stress, anxiety and sleep. Over time, this combination supports more resilient mental health.

5. Fighting inflammation: anti-inflammatory eating + consistent activity

Chronic, low-grade inflammation is linked with many age-related conditions. Anti-inflammatory dietary patterns – rich in vegetables, fruit, whole grains, legumes and healthy fats – help keep this in check. Regular movement amplifies the effect by supporting immune regulation and reducing inflammatory markers over time.¹¹

Don’t forget the other aspects of a healthy life

As we hope you can see, nutrition and exercise are interconnected. This is true for our overall wellbeing. Our food choices affect energy, motivation and how we recover. Movement can keep us in shape to support the other activities in our lives, while improving our mood and stress responses.

Rest is equally essential. Think of sleep as a third pillar of wellbeing, sitting alongside nutrition and activity. The way we eat and exercise directly affects sleep quality, which in turn shapes metabolism, emotional regulation, cognitive focus, and overall energy. A balanced routine supports a stable sleep rhythm, and better sleep reinforces healthier behaviours the next day.

Scientists are also starting to see the profound role of social connection in long-term health.¹² Community, shared meals, and movement with friends strengthen emotional resilience and can support our health in ways we are only now starting to understand.

A balanced, real-world approach

 There is no single winner in the “food versus exercise” debate – both are vital for supporting our physical and mental health. Finding the right balance can be difficult, especially on busy weeks, so aim for progress rather than perfection. Planning meals ahead of time and fitting in some movement a few times a week can make a meaningful difference. Even a brisk walk around your neighbourhood counts.

And don’t forget the importance of sleep and social connection. Next time a friend invites you out for a meal or a drink, say yes – and suggest meeting for a jog or Zumba class first. Bonus points if you’re home in time for a good night’s sleep!