Is diet or exercise more important for weight loss?

Joel H. Fuhrman, MD
Family Medicine
Exercise is an important part of health and longevity, but it's not the key to weight loss; changing our diet and how we eat is. Watch me explain why diet is the more important factor for weight loss.
Judy Caplan
Nutrition & Dietetics
This is a trick question! I find it difficult to separate the two. Although it is possible to lose weight, albeit harder to do without exercise, it is not recommended. You can lose weight without exercise but it is almost impossible to keep it off without exercise. For long term weight loss I believe exercise is more important. While eatingis necessary for life, it is also emotional, enjoyable and fun. There are times when we over indulge. Exercise can prevent weight gain at these times. It increases your metabolism, keeps you in touch with your body, and makes you more aware of what you are doing. It is one of the main keys to long term weight maintenance.
Ruth Frechman
Nutrition & Dietetics

Tough call. I will say exercise. Cardio and strength training builds muscle mass. The more muscle you have, the faster your metabolism, which will help you burn more calories. Technically, you could eat three candy bars and day and lose weight, because you aren't eating very many calories. However, that would not be healthy.

Tanya Zuckerbrot
Nutrition & Dietetics

Both! Diet in combination with exercise is the most powerful formula for losing body fat. Your body weight is determined by the amount of calories you take in and the amount of calories you burn: you take in more calories than you burn and you will gain weight. While dieting controls caloric intake, adding exercise burns excess calories that otherwise would be stored as fat! 

Dieting may help you lose weight temporarily, but dieting without exercise does not help you keep the weight off! By decreasing your caloric input AND increasing your daily physical activity, you will lose excess weight in the most efficient and healthful way with a better chance at keeping the weight off! 

You've got to look at diet and exercise as the dynamic duo.

They go hand in hand in creating a successful weight loss program, and are both necessary to support optimum health.

While you can lose weight by simply reducing the number of calories you consume, maintaining a calorie deficient diet is unsustainable for the long term. A calorie deficient diet forces your body into starvation mode causing it to burn muscle before fat, increasing your chances of gaining the weight back at the end of your diet, and making losing fat in the future even more challenging.

In order to lose weight and keep it off, you need to create a lifestyle change which incorporates a healthy diet rich in whole foods like fresh fruits and vegetables, whole grains, lean meats, and healthy vegetable fats from nuts and seeds. Eating a low calorie nutrient rich diet will aid in fat loss as well as improve your energy and mental focus. Adding to healthy diet, an exercise routine that incorporates cardio aerobic workouts with interval and resistance training ensures that your body will burn excess calories for weight loss and become strong and fit allowing for optimum functional mobility. 

Jessica Crandall
Nutrition & Dietetics

Diet vs. Exercise, what a thought…If we lived in a perfectw world, we would be able to choose an option. However, when it comes to weight loss, there is no selection between diet and exercise; both are needed and just as important. Having a proper functioning diet and exercise plan working together will only help you meet your goal. Why would you want to go to the gym for 1 hour just to go home later that day and eat whatever you find? All of that hard work would have been for nothing. You can start off small with adjusting your diet to become more balanced as well as adding in a small amount of exercise during the day. Every minute of exercise counts! In the morning, park at the far end of the parking lot and walk to the building, take the stairs, start a walking group during lunch and bike with the family after dinner. All of this counts towards the goal of at least 30 minutes per day.

AAcombination of both diet and exercise can best help you achieve a healthy weight. You should avoid fast fix diet fads that may produce a quick initial weight loss, but can’t sustain a healthy weight. General diet recommendations include awareness of portion sizes and replacing empty calorie foods (foods with lots of calories, but little nutritional value) with nutrient rich foods (such as fruits, vegetables, whole grains, and lean proteins).
Exercise helps to boost your metabolism and burn calories to help you reach a healthy weight. You should aim for at least 60 minutes of activity each day. This should include at least 20-30 minutes of activity that gets your heart pumping. However, this doesn’t have to be on a treadmill or a kickboxing video. It can be, but it could also be biking, playing basketball, fast walking, skating, etc. Choose something that is fun for you and also gets your body in shape. 
Neal Spruce
Neal Spruce on behalf of dotFIT

Diet is far more effective and easier in producing weight loss but exercise is just as important in maintaining the loss and in delivering substantial long-term health benefits that diet alone cannot.

Here are the latest facts:

The latest exercise and weight study published in the Journal of American Medical Association (JAMA) completed in March 2010 followed 34,000 chronic exercisers for 13-years and the average weight GAIN was 6lbs. 13.3% of those who gained slightly less but still GAINED, performed 60min/day of moderate to vigorous exercise and were normal weight at the start. Conclusion from study:

Exercise alone is not a weight loss program for anyoneIf overweight, it’s too late to reverse it with exercise alone, you must restrict calories

Earlier short term studies comparing diet alone and exercise alone were even more dramatic:

Diet alone groups lost an average of 19.8LBS in 6-months, while exercise alone groups lost less than 2LBS in the same period.

Final note:

One single fact determines the rate of weight/fat loss: your average daily calorie deficit. This is defined as the difference between how many calories you burn and how many calories you consume. Therefore it’s easier to remove 500 calories of food from your daily diet to produce a 1lb/wk loss of weight than it is to perform 1.5 hrs/day of vigorous exercise to accomplish the same result. That said, exercise is needed to improve your body structure, function/performance, longevity, visual appearance, etc. Exercise also increases daily calorie burn and helps you maintain your desired weight. So participating in both proper diet and exercise, you get faster, healthier and sustainable weight loss.

For optimum results and overall health, exercise and diet are equally important. In order to lose weight you need to consume less calories then you expend in a day. 1 pound of fat equals 3500 Calories. If you're energy expenditure is 2300 Calories a day, for example, reducing 500 calories from your daily diet will allow you to lose approximately 1 pound a week. With regular cardiovascular exercise, you expend more calories which will create a greater reduction in weight. Strength training along with cardio exercise is important to change body composition and help you to continue burning calories post exercise. Once weight loss is achieved, exercise is needed to maintain it.

Michaela Ballmann
Nutrition & Dietetics

I consider diet and exercise to be the "Dynamic Duo" when it comes to weight loss. Exercise can help you create a negative energy balance and build lean body mass, which burns more Calories at rest and all throughout the day than fat.

However, if thought of making diet changes as well as starting a more intensive exercise program seems overwhelming, I would start with diet. By changing the types of foods you eat and the amount of Calories you consume (by 500-1000 kcals/day), you can safely lose about 1-2 pounds per week. Slow, steady weight loss through diet is definitely the way to go.

As I mentioned, exercise can also be a powerful weight loss tool, but it can also be a hindrance. Let me explain. When people exercise, they often either feel hungrier or they feel that they deserve to eat more food or treat themselves to dessert. By doing so, the Calorie deficit that could have been created by exercising is now made into Calorie balance where no weight will be lost or even weight gain if excess Calories are consumed.

People can also be “thrown off” psychologically when, through exercise, they simultaneously gain muscle and lose fat but the number on the scale doesn’t budge (or goes up). Though their trainer or dietitian tells them to expect this and that their focus should be on their health and how they feel, people often get discouraged when focusing solely on the amount of pounds they weigh.

Both should be part of your routine to achieve lasting weight loss. The Law of Thermodynamics states that in order to lose weight you must burn more energy than you consume. Based on this principle both diet and exercise share equal importance in achieving weight loss. That said if you are completely new to a fitness and nutrition routine you might want to start with one routine and add the other in time. The reason I suggest this is making dramatic changes to your diet and implementing a new exercise routine simultaneously may be overwhelming and result in you getting discouraged. Remember lasting weight loss is the result of hard work and lifestyle change.

Both should be part of your routine to achieve lasting weight loss. The Law of Thermodynamics states that in order to lose weight you must burn more energy than you consume. Based on this principle both diet and exercise share equal importance in achieving weight loss. That said if you are completely new to a fitness and nutrition routine you might want to start with one routine and add the other in time. The reason I suggest this is making dramatic changes to your diet and implementing a new exercise routine simultaneously may be overwhelming and result in you getting discouraged. Remember lasting weight loss is the result of hard work and lifestyle change.

Dr. Mike Clark, DPT
They are both important. I like to advise people to create a long term view for effective weight loss. There are 3 P's that are important to understand for weight loss.  P1 (Psychology): You must have a specific, measureable, attainable, and time bound weight loss goal and you MUST have a clear and powerful "WHY" that will drive you. This starts in your mind. P2 (Physiology): Begin by eating 500 less calories/day, walking 10,000 steps/day, sleeping 8 eight hours/night, and taking a multi-vitamin. P3 (Physical): Once you have your mind right and your calories under control, now begin an exercise plan to "get fit". Be patient. Be persistent. Be clear and be realistic. It is going to take time to lose weight and get healthy. You didnt gain the weight overnight and you will not lose it overnight. Living healthy and fit is a mindset and ultimately your choice. You get to choose what you eat and how much you move. Make the healthy choice. Good luck!
Losing weight is a matter of creating an imbalance between the number of calories taken in and the number of calories burned.

Historically, weight-loss programs focused solely of food intake. The more current approach integrates regular activity into the weight-loss phase, so that planning and participating in physical activity becomes as much a part of one’s life as healthful eating habits as physical activity is a critical factor for weight maintenance.

That being said, activity is not an effective stand alone weight-loss method. It is much easier to reduce calories through food intake than to be able to achieve the amount of physical activity alone that is needed for weight loss. A successful weight-loss program must include an approach focused on healthy eating, regular physical activity, behavior modification and a supportive environment.

Weight Watchers offers a comprehensive approach to weight loss that can help you reach your goals.
Great question! The old saying is "you are what you eat". Eating a balanced-healthy diet can promote healthy body-weight. However, adding exercise can help maintain a healthy body-weight and build necessary muscle. Basically, do both and become a healthier you. I hope this helps and have fun.

Proper nutrition and exercise are both needed for weight loss. Proper nutrition is 80% responsible for weight loss, while 20% is exercise. I want to make it clear that you need both to have effect weight loss. Build muscle in the gym. Eat right outside of the gym.

Both proper diet and exercise are needed for weight loss. There should be an equal balance between the two for you to receive optimal results. Many people often think that if you concentrate on one more than the other you will receive the best results. However, proper diet and exercise are a "team" and should be focused on together. For example, if you eat poorly and workout about 3 times a week, you may see some results. But if you are eating a well-balanced diet and working out 3 times a week you will see results faster.

Both diet and exercise are critical to your weight loss efforts. A great fitness plan will fall short if you do not support it with proper nutrition and calorie intake. A great diet will help you lose weight but a good strength routine will shape you and help you burn more calories. To get the best results both are important!
Laura Motosko, MSEd, RD
Nutrition & Dietetics

Diet and exercise are both important to produce an energy deficit which will lead to weight loss. In my opinion, a calorie controlled and nutrient dense diet is essential to produce weight loss. Exercise is essential to maintain the weight lost. A combination of both is most effective for weight loss and weight maintenance.

Diet is going to be the bigger change to make because it usually means you're giving up something you like, namely food and drink. Weight loss is as simple as taking in less calories per day than you use, when you take in more calories than your body uses it gets stored as fat. Exercise will burn calories; however, until you get your food intake to the point where you have a caloric deficiency then the exercise will strengthen you but you won't lose weight. Because I can be a body builder that can lift 500 lbs but still have a tire around my midsection because I take in more calories than my body uses and it gets stored as fat. The real answer is to do both in conjunction.

The answer to this question truly depends on the individual. Diet and exercise are both critical components to weight loss success but the current lifestyle choices of the individual would have the greatest effect on the initial assessment. If an individual is already active but their diet consists of mainly fast food then the most important aspect of that individual’s weight loss routine would be diet. If the individual has an average diet but little activity then that individual may want to focus on developing a proper exercise routine while making modifications to their diet. Both diet and exercise are critical, that is why it is important to consult a fitness professional before engaging in any fitness program---making sure YOU are doing what is right for YOU.  

Diet and exercise are both important for weight loss, but diet trumps all.  You can't exercise your way out of a diet of fast food and junk food.  For those you are injured, a proper diet will stll lead to weight loss, though the best results are for those who eat right and exercise. 

My preference is a low-fat, whole foods, plant-based diet, with no added oils.  It's hard to overeat, the fiber in the food will fill you up.

Both. Although, exercise burns calories, a "bad" diet can sabotage your efforts for weight loss and body composition.

Kelly Currier
Nutrition & Dietetics
Although focusing on at least one of these lifestyles is better than completely throwing caution to the wind, you will never reach optimal condition without devoting yourself to a healthy lifestyle that includes diet and exercise. Diet and exercise offer equally important, but usually different health benefits. For instance, you could eat very little animal fats and stick to plant oils and have a great LDL (bad) cholesterol level but a very poor HDL (good) cholesterol level because exercise is the most effective way to increase HDL. On the flip side, you could train for marathons and have great HDL levels but have very high LDL levels if you eat poorly. You need to give good effort to both.
Alberta Scruggs
Nutrition & Dietetics

Both are equally important and essential for weight loss. However, what you put in your mouth has a huge influence on the caloric deficit you want to make, initially. For instance, if you exercise two hours a day but eat more kcalories than your body requires, eventually you are going to be a fit overweight person (It may sound strange, but there are many). If you choose to eat empty kcalorie foods such as potato chips, candy bars or drink sodas, when you exercise (and it has to be a lot of exercise), you’ll be working only to get rid of the kcalories from these foods not to make the caloric deficit you want.

You want to be knowledgeable with food selections, making sure you’re providing your body with the essential nutrients necessary, even though you are striving for weight loss. You can’t complete the exercise component of a weight loss program if you become ill.

Once you begin making a caloric-deficit with food selections, exercise takes the lead (and is vital), in assuring weight loss continues until weight management is your goal. Exercise boosts the metabolism, which helps burn kcalories, and promotes heart/muscle strength, improved body image and confidence.

Both are important so be sure to include both in your weight loss program.  The key to weight loss is consuming fewer calories than you burn.  The best way to accomplish this is by making simple changes to the way you eat, and increasing your daily activity.  Make sure you are doing aerobic exercise at least 2 to 3 times per week as well as resistance training at least twice per week.  By including resistance training, you can swap body fat for lean muscle mass (LMM).  For every additional pound of LMM you create, you burn 100 calories more per day. You could lose 15 pounds of body fat, put on 5 pounds of LMM so it will only show as a 10 pound weight loss on the scale.  However, you will be thinner, your clothes will feel looser, your metabolism will be fired up longer, and you will feel better.

Simple diet changes include portion control.  Be sure to measure everything you eat at first until you get comfortable with visualizing a portion size.  The new My Plate program at has great information to help you make the right choices and to know what a portion size should be.

This question will always draw many answers. It is safe to say that they are both important.

Recent recearch would suggest that about 90% of weight loss is diet. However, about 90% of weight maintenance is exercise!
The key is balance and being realistic.   Bottom line - there are 3500 calories in a pound - burn that or more and lose weight.  A key mistake people make is overestimating the amount of caloric loss that exercise causes, and underestimating the amount of calories they are eating.  Exercise, while it initially tamps down our appetite, later on, often results in increased appetite - and folks give themselves more "permission" to eat more when they exercise - often well exceeding the amount they burned.  If you were FORCED to choose one - then controlling diet/calories is more likely to get you there, but the myriad benefits of exercise including vitality, immune benefits, stress relief, and yes - calorie burning - make it an essential part of a weight loss plan.
Heidi Skolnik, MS
Sports Medicine

I love this question! Do you know that you would need to walk 64 minutes to burn off eating one doughnut, you would need to cycle 82 minutes to burn off the calories consumed by eating one Big Mac or jog 32 minutes for one order of Cheese fries. 1 pint of Hagen Daaz will cost you an hour and 22 minutes of jogging…so you can see that depending on exercise alone to lose weight is literally an uphill battle.

It is essential to become mindful of food selection and portion size for successful weight loss.   Exercise is extremely helpful for several reasons. Exercising while one loses weight, especially if participating in some resistance training, will help you lose fat while limiting the amount of lean mass that is lost.  This is important because muscle is what is metabolically active-meaning muscle burns more calories even at rest (and helps with glucose tolerance amongst many other health benefits).  When weight is lost through diet alone, we tend to lose more muscle mass.  Exercise also helps burn calories to help tehcalorie deficit needed to achive weight loss goals and can help reduce stress that often contributes to overeating.

However, depending on exercise to lose weight without paying attention to diet is not a great strategy.  So—eat, but not too much, and exercise, at least enough and together you are on your way to improved health and well-being!

Wendy Batts
Just like you might think, both are vital to healthy weight loss. With that being said, you can lose weight with diet alone if needed. Exercise alone, while possible, would be much more of a challenge. To lose weight, we need to create a gap between the calories we burn and the calories we eat so that we are burning more than we consume.

It is much harder to create that gap with exercise alone without changing the amount of calories that we eat. We can however reduce the number of calories we eat to create the gap a little more easily. So your question may be “Why then would I want to do both?” Exercise has numerous physical and psychological health benefits, many of which directly contribute to a weight loss goal. For example we burn more calories not only during the workouts, but in the recovery period after the workouts (aka the after-burn). This aids even further in creating the calorie gap between what we eat and burn. Exercise helps reduce the risk of diseases such as hypertension and diabetes. Aesthetically as well, the sculpted or toned look that many of us desire also comes about from regular resistance and cardiorespiratory exercise. And many regular exercisers just feel better and have more energy, enabling them to maintain a steady level of activity, and therefore calorie burning, throughout the day.

The more calories you burn, the more you actually get to eat and still lose weight! That’s the best reason yet to include exercise in your weight loss program. And once you achieve your goal weight, exercise is vital to weight maintenance.

So bottom line is that both are equally vital to lasting weight loss.
They go hand in hand-you can't healthily do one without the other. Finding the right percentage of each is your individual key to weigh loss success.  It varies for everyone. For me it is 60% diet and 40% exercise.
Dr. Michael Roizen, MD
Internal Medicine
If you have to choose one, choose both. Smaller portions will make you feel good enough to exercise. Physical activity will boost metabolism, increase feel-good brain chemicals, and improve your outlook on life.

You really can’t have one without the other to have healthy, long term weight loss.  We all know that excessive calorie cutting or excessive exercise can make you lose weight.  But I want to see the people that tried these methods and didn’t have to pull out their fat pants once again.  It just can’t be done and it’s not good for you! A great plan to get started for women would be to lower your calories to 1200-1500 a day, increase your daily steps to 10,000 and do simple body weight exercises around your house like lunging, squatting, push-ups and ab work.  A weight loss goal of 2 pounds per week is a realistic, yet attainable, goal.  Adding in this healthy eating and exercise plan will jump start you to losing weight today and help keep it off for many tomorrows.  And be sure to keep a pair of those fat pants as a reminder of just how far you have come!

Most research shows that weight loss is more effective when cutting back on calories as opposed to only increasing physical activity. However, weight loss is much more effective when both a decrease in daily caloric intake, and an increase in daily physical activity are combined. Therefore, both diet and exercise are equally important when it comes to weight loss.

For weight loss to occur we must burn more calories than when consume. For successful long-term weight loss you must commit to making lifestyle changes that you can maintain for life. There is no magic pill, fad diet or temporary exercise program that will give you long term weight loss success. To maintain weight loss for life, you need to commit to a healthier lifestyle for life by becoming more physically active, along with consuming a more nutritious diet on a daily basis. The goal is to move more, and eat less!

Both are essential to weight loss. It's a simple math equation. For proper weight loss, you cut your caloric intake and increase your daily burn.

One without the other can lead to short term weight loss but does not provide best long term solution. 

Dominique Adair

Not only are both exercise and healthy nutrition critical for weight loss I would not even try to prioritize them.  We see articles and statements positioning one as more important than the other but that seems to be just a convenient way to devalue one or overvalue another for weight loss success.  Bottom line, these are lifestyle changes, as exercise and healthy eating go hand in hand.  In fact, some studies show that weight loss program participants have an easier time losing weight with a combination of both.  So, instead of thinking of one OR the other, think of making your life EASIER in the long run.  One important tip, choose exercise(s) that you enjoy and a nutrition plan that you can stick with for the long haul, because lifelong is a long time, we hope!

There are many factors to consider when it comes to weight loss. Some people have a genetic risk of being overweight and may have a harder time than others when it comes to shedding pounds. Other people are stuck in a sedentary lifestyle that’s difficult to change. The problem is, when you take in more calories than you burn off, you will gain weight. While you can cut back on your calories and stay within a certain daily quota, you can also eat a healthy diet and use more calories by being more active.

So, both diet and exercise are important components for healthy weight loss. If your doctor recommends that you lose weight, you can do this by moving around a lot more (aim for 300 minutes a week of moderate intensity aerobics) or you can reduce the calories you ingest -- or do both.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.