You’ve probably heard that “you can’t out-exercise a bad diet.”

While this saying has some merit, you may wonder whether diet or exercise is more important for health goals like weight loss or improved heart health.

With endless health interventions out there, such as the 80/20 rule and exercise-free diets, it can be hard to gauge whether you should prioritize diet or exercise — or if the answer lies somewhere in between.

This article tells you the benefits of exercise and diet, and if one is more important for your health than the other.

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Weight loss

To lose weight you must be in a calorie deficit, meaning your body expends more calories than you consume. This can be achieved by eating and drinking fewer calories, burning more calories from physical activity, or a combination of the two (1).

Benefits of diet

While both diet and exercise are important for weight loss, it’s generally easier to manage your calorie intake by modifying your diet than it is to burn significantly more calories through exercise.

This may be why the 80/20 rule has become popular, as it states that weight loss is the result of 80% diet and 20% exercise.

For example, if you’re aiming for a daily calorie deficit of 500 calories, you could consume 400 fewer calories (80%) by eating lower calorie dishes, smaller portion sizes, and fewer snacks. Then, you only need to burn 100 calories (20%) from exercise.

For many people, this is easier than trying to burn 500 calories each day from exercise. Burning this many calories every day requires a significant amount of movement — plus, it’s time-consuming, taxing on the body, and rarely sustainable.

To illustrate, a person who weighs 154 pounds (70 kg) would need to cycle on an exercise bike for 1 hour at moderate intensity to burn 525 calories. Meanwhile, they could cut out 520 calories by skipping out on a venti Green Tea Frappuccino from Starbucks (2, 3).

An easy way to manage calorie intake and promote weight loss without counting calories is to focus on eating whole, minimally processed foods that are high in fiber, protein, and healthy fats (4, 5, 6).

Benefits of exercise

There are many ways that exercise supports weight loss.

Strength training helps preserve and build muscle mass, which can increase your metabolic rate over time so your body burns more calories, even at rest. Furthermore, a single strength training session can increase your metabolic rate for up to 72 hours (7, 8).

Aerobic exercise such as walking, jogging, or cycling — especially at a low to moderate intensity for 30 minutes or longer — can burn a significant number of calories in a single session and help promote a calorie deficit (2, 9, 10).

Regular exercise may also help manage hunger by regulating your hunger hormones. This may help prevent overeating and excess snacking. That being said, excessive exercise may increase appetite as well as injury risk, so moderation is best (11, 12, 13, 14).

Finally, by burning extra calories and increasing your metabolic rate, regular physical activity allows you to have more flexibility with your diet, making weight loss more enjoyable and less restrictive (15).

Exercising regularly also supports weight maintenance after weight loss, which is critical (15).

Exercise improves health whether or not you lose weight

Popular diet culture might make it seem like you need to lose weight to be healthy, but experts have found that’s not the case.

Increasing your cardiovascular fitness and physical activity promotes better health regardless of weight loss (16).

Studies have found physical activity improves many different factors independent of weight loss, including markers of health at the cellular level, levels of HDL (“good”) cholesterol levels, artery stiffness, levels of fats in the blood, brain health, and more (17).

Recommendation: Combination of diet and exercise

Although the 80/20 rule is a helpful guideline, you don’t have to follow it precisely. Instead, focus on making positive changes to your diet and exercise routine that work for you.

For instance, you may prefer achieving your daily calorie deficit 50% from diet and 50% from exercise. This means you’ll spend more time and energy exercising — but in return, you won’t need to limit your food intake as much.

The key for healthy, long-term weight loss and management is to use both diet and exercise (1).

In fact, one older review showed that combining modest calorie restriction and exercise was the best way to achieve significant weight loss. In some cases, combining the two led to over five times more lost weight compared with using exercise alone (18).

A 2023 systematic review found that adults with obesity lost the most weight using a combination of strength training and endurance exercise for at least 175 minutes each week, plus a customized diet in which they ate fewer calories than they burned each day (19).

Ultimately, combining dietary changes and regular exercise can help you achieve more meaningful and sustainable weight loss in the long term.

Summary

While it may be easier to manage how many calories you consume, regular exercise helps preserve lean muscle and burn additional calories. Therefore, both diet and exercise are important for weight loss, and combining the two will optimize results.

Heart health

Both exercise and diet play significant roles in heart health.

Benefits of diet

The foods we eat can support or hinder heart health.

The dietary patterns associated with reduced heart disease risk are centered around minimally processed vegetables, fruit, whole grains, healthy fats, and lean animal and plant-based proteins while being low in sodium (20, 21, 22).

For example, the well-established Mediterranean diet promotes heart health. It’s high in healthy unsaturated fats from olive oil, fish, and nuts, dietary fiber from whole grains and vegetables, and antioxidants that help fight harmful molecules called free radicals (23, 24, 25, 26, 27).

Plus, it contains limited amounts of saturated fats and added sugars due to its focus on fresh, minimally processed foods (23, 24, 25).

The Dietary Approaches to Stop Hypertension (DASH) is another evidence-based eating style similar to the Mediterranean diet.

It encourages less sodium and more potassium and fiber by prioritizing whole, minimally processed foods like vegetables, fruit, and whole grains (25, 28, 29, 30).

Diets high in saturated fats, sodium, added sugars, and refined carbohydrates from processed and red meat, sugar-sweetened beverages, baked goods, and highly processed snack foods like chips are linked with a higher risk of heart disease (25, 31, 32, 33, 34).

Benefits of exercise

Numerous studies have shown that exercise can help lower your risk of heart disease, decrease blood pressure and LDL (bad) cholesterol levels, increase your heart’s size and strength, and improve cardiorespiratory fitness (35, 36, 37).

Even if you don’t lose weight, you may experience these benefits when exercising regularly (16, 17).

Moderate to high intensity cardio exercise strengthens the heart, allowing it to push more blood into your body with each heartbeat. This decreases the amount of stress on the heart and arteries, which lowers the risk of heart disease (35, 36, 37).

What’s more, regular exercise can reduce your risk of developing type 2 diabetes — which is strongly linked to heart disease — by improving insulin sensitivity and blood sugar control (35, 36, 37).

General recommendations include getting either 150 minutes of moderate intensity exercise, 75 minutes of high intensity exercise, or a combination of the two each week for optimal heart health (35, 38).

Even a low intensity aerobic activity such as walking may reduce your heart disease risk (35).

Keep in mind that if you have heart disease or another chronic condition, you should speak with your healthcare professional before starting a new exercise program.

Recommendation: Combination of diet and exercise

Combining a nutritious diet with regular physical activity is one of the most effective ways to reduce your risk of heart disease (39, 40, 41, 42, 43).

Other lifestyle changes that improve your heart health include quitting smoking, limiting or eliminating alcohol, maintaining a weight that is healthy for your body, and managing stress (42, 44, 45, 46).

Summary

Consuming a minimally processed, whole-food diet rich in healthy fats, fiber, and lean protein is linked to better heart health. Along with this, regular exercise keeps your heart stronger and reduces certain risk factors for heart disease.

Other facets of health

Diet and exercise can play important roles in other areas of your health, too.

Building muscle

To build muscle, you need to do resistance training with progressive overload and eat enough protein throughout the day.

Progressive overload involves gradually increasing exercise volume and load — through higher weight, more sets, or more reps — to stress the muscles (47, 48).

If you don’t challenge your muscles through resistance training, you won’t build muscles simply by eating a high protein diet. Likewise, if you do engage in strength training exercise but don’t consume enough protein, it will be difficult to gain muscle (47, 48, 49).

Therefore, both diet and exercise are important for building muscle.

Mental health

A nutritious diet rich in healthy fats, fiber, probiotics, vegetables, and fruit is associated with improved mental well-being and a lower risk of anxiety and depression (50, 51, 52, 53).

Further, low levels of certain nutrients including zinc, vitamins D and B12, and omega-3 fats are linked with worsened mental health (50, 51, 53).

Exercise can also provide both immediate and long-term benefits to mental health. It promotes the release of mood-boosting endorphins — such as dopamine, serotonin, and norepinephrine — that temporarily improve your mood and stress levels (54, 55).

Additionally, regular exercise is associated with lower rates of moderate depression, anxiety, and other mental health conditions (56, 57, 58, 59).

In addition to any treatment recommended to you by your healthcare professional, regular exercise and a nutritious diet may improve your mental well-being.

Summary

Both diet and exercise have been shown to promote muscle building and improve mental health.

The bottom line

Diet and exercise are both important for optimal health.

Achieving a calorie deficit through diet modifications is key for weight loss, while exercise provides many benefits that help sustain your results.

Further, both exercise and diet can help reduce heart disease risk, build muscle, and improve your mental health.

To promote good overall health, it’s best to consume a minimally processed, whole-food diet full of healthy fats, fiber, and lean protein. Also, aim to get at least 150 minutes of moderate to vigorous exercise each week.

While you may be tempted to pick one over the other, diet and exercise work hand in hand, and combining both will optimize health and quality of life.

Just one thing

Try this today: Not sure where to start? Try to pick just one small diet change and one small exercise change. Stick to them for a few weeks to a month, then build on top of that.

Whichever changes you choose, write them down to keep yourself accountable. Over time, your small changes will add up to make a big difference.

Here are some ideas for small diet changes:

• Include a vegetable with each meal.
• Eat at least three different colors of fruits and vegetables each day.
• Incorporate plant-based protein like beans or lentils at least twice per week.
• Replace one refined snack with a piece of fresh fruit per day.
• Limit alcohol to one drink per day or 1–2 days per week.
• Choose a whole grain version of your favorite carb-rich food, such as brown rice over white rice.

Here are some ideas for small exercise changes:

• Walk for 15 minutes at least 3 times per week.
• Spend 10 minutes of your lunch break stretching or walking.
• Visit the gym or go for a jog two times per week.
• Follow an online yoga video for 20 minutes 2–3 times per week.
• Join a sports club that you think sounds interesting.
• Go for a long walk with a friend once per week.