You’ve probably heard the saying, “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 delves into the intricate relationship between exercise and diet, highlighting the benefits of each and exploring their combined impact on various aspects of health, from weight management and heart health to muscle building and mental well-being.
Weight Loss: A Calorie Balancing Act
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.
The Role of Diet in Weight Loss
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).
The Role of Exercise in Weight Loss
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).
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The Power of Combination
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.
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: A Lifestyle Symphony
Both exercise and diet play significant roles in heart health.
The Role of Diet in Heart Health
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).
The Role of Exercise in Heart Health
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.
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The Power of Combination
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). 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.
Beyond Weight and Heart Health: Additional Benefits
Diet and exercise can play important roles in other areas of your health, too.
Building Muscle: A Combined Effort
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: Nurturing the Mind and Body
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.
Both diet and exercise have been shown to promote muscle building and improve mental health.
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Practical Tips for Integrating Diet and Exercise
Maybe you’ve recently made a fitness commitment to a friend, joined a local gym, or even registered for an upcoming run. Whether you’re looking to shed that winter weight in time for summer or simply trying to make some changes to your day-to-day health, you’ve likely noticed that what you eat throughout the day has a major impact on your body’s performance. Poor diet and physical inactivity are linked to increased risk of diseases, such as heart disease, cancer, and type 2 diabetes, that have become leading causes of death in the United States. Here are some practical tips for integrating diet and exercise into your daily routine:
- Embrace Variety in Fruits and Vegetables: Eat the fruits and vegetables that you like. If you don’t like broccoli, don’t eat broccoli. Instead, opt for zucchini, asparagus, or maybe even kale. There are hundreds of edible fruits and vegetables at your disposal, so don’t feel as if you’re limited to certain ones. "Every single cell in the body is made up of the nutrients that we take in, which impacts the body’s function. In order for our bodies to perform well, we need to provide our bodies with the right fuel and building blocks. While most of what you’re getting from your diet likely fuels your usual activity, incorporating healthy food options into your diet can help with your performance and recovery,”
- Practice Mindful Eating: Start listening to your body by eating only when you’re hungry. Mindful eating takes practice, especially in today’s fast-paced environment where it’s easy to get distracted. Your body will tell you what it wants, but it’s important to pay attention to the “why,” making sure you’re not partaking in eating because of something else that’s going on. It also isn’t necessary to give up all of the things you like, such as red meat or that freshly baked chocolate chip cookie. Just remember, moderation is key. “You can honor your hunger and honor your cravings without guilt,”
- Find Joy in Movement: Find a form of exercise that you enjoy. Maybe you’re not a runner, but you like to take walks in the evening after dinner. Maybe your partner is a CrossFit fanatic, while you prefer to engage in meditation practices in the form of yoga. Exercise does not have to be hard, and there are many benefits to participating in light to moderate activities. “There is this irrational notion that exercise has to be hard, it needs to be high intensity, and you have to get sweaty to benefit from it. However, the best form of exercise is engaging in an activity that you enjoy, because then you know you’re actually going to do it,”
- Celebrate Small Victories: Create and celebrate small milestones. There are plenty of other benefits associated with living a healthier lifestyle than weight loss or weight management. Healthier eating habits make exercising more enjoyable, and exercising gives you more energy, helps you sleep better, and reduces your stress levels. These small wins are worth celebrating. “People have a general idea of what a healthy diet looks like and know they should be exercising,” shares Dr. Zuniga. “Where people run into a lot of barriers is when they tell themselves they have to make a huge overhaul in their lifestyle overnight in order to benefit their health, which is simply not the case.
- Embrace Imperfection: At some point, you are going to fail, and it’s okay to fail. Not all goals will be obtainable all of the time. You may want to meal prep five days a week, but later find that to be too ambitious of a goal and need to cut it back to three days a week. Or, you may have to abandon your workout plan for an extended period of time to accommodate a life change. We get it, life happens. “Sometimes you fall off track because you went on vacation or you had a bad week. That’s okay. Reassess and reevaluate your situation to determine where to pick back up or make a change,”
- Steer Clear of Fad Diets: Stay away from crash, fad, and cleanse diets. These short-term diets encourage you to restrict your eating habits in exchange for rapid weight loss. While you may see some immediate changes to your body, the reality is that those changes are fleeting. Once you return to your former habits, you’re soon to be back at square one. Restrictive diets are more difficult and challenging than a healthy lifestyle needs to be. Rather than counting down the days until the diet is over, you can gradually incorporate changes that you will benefit from long-term. “Crash diets create a lot of restrictions, and whenever you restrict something, you tend to hyper focus your energy on that item. If you’re going 30 days without eating your favorite dessert, at the completion of those 30 days, you may find yourself overindulging,”
- Take Ownership of Your Goals: Take accountability for your diet and exercise goals. You may have an idea of where you can start making changes to your diet and daily activity, but you have to find a way to execute and monitor that change. “When it comes to diet and exercise,” says Dr. Zuniga, “there is no one-size-fits-all. As a dietitian, I work to empower patients by providing them with knowledge to help them make healthy choices.