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What is More Important in Weight Loss: Exercise or Diet?

Medically reviewed by John Paul Abrina, MD · Oncology · Davao Doctors Hospital

Written by Lorraine Bunag, R.N. · Updated Jun 21, 2021

    What is More Important in Weight Loss: Exercise or Diet?

    Weight loss is a common goal for many of us, and it has proven to be a challenge. How should we go about shedding off the extra pounds? Should we focus more on fat-burning exercises or diet and nutrition? In this article, we will explore the “80 diet 20 exercise” theory.

    What is the 80 Diet 20 Exercise Theory?

    When we usually think about diet and exercise in connection to weight loss, we tend to say that they are both important. However, we don’t quantify their importance.

    Come to think of it, if we say both are essential, does it mean that for weight loss to happen, our efforts must be centered 100% on diet and 100%, too, for exercise? According to experts, that is a vague approach.

    Between nutrition and work out, we should pay more attention to our diet and less on our physical routines. That is the core principle of the 80 diet 20 exercise theory.

    But why should we pay more attention to our diet and less on our physical activities? To explain we need to understand more about calories.

    Basic Concepts About Calories

    • Calories are energy. We need to take in calories through nutrition, so we can burn them to produce energy.
    • The body uses the energy to perform basic functions to keep our body performing at an optimal level. This is called the Basic Metabolic Rate or the number of calories we need to keep our bodies functioning. Use our tool to know your BMR.
    • We also burn calories for normal day-to-day activities and other strenuous physical exercises, such as running, swimming, and basically working out.
    • Unused calories are stored as fat tissue.

    Here’s an important point for the 80 diet 20 exercise theory: to lose weight, you need to have fewer calories than you use (calorie deficit).

    Now, “having less” calories can be achieved in two ways: either we burn the excess calories through working out, or we cut our calories through diet.

    The Big Idea Behind the 80 Diet 20 Exercise Theory

    Now that we covered the basic concepts of calories, let uss discuss the big ideas as to why diet is more important than working out.

    You Have More Chances to Lose Weight Through a Diet

    What is your chance of losing weight through diet? And what’s your chance of losing weight through exercise?

    To answer this, think about the number of times you eat versus the number of times you work out.

    • If you exercise for about 30 minutes to an hour daily, then you will have 7 “chances” to lose some weight in a week. Should you be more active than this, you can have more; if you lead a sedentary lifestyle, you will have fewer chances.
    • Now, think about how many times you eat in a day and multiply that to a week. A diet with the normal 3 meals a day would already give you 21 chances to lose weight.

    If you will think carefully about your food choices, you can maximize the weight-loss potential of each meal. Thinking carefully means choosing your food based on their nutritional value to ensure that you are cutting back on calories or at least not adding unnecessary calories in your body.

    It is Not Practical to Lose More Weight through Exercise

    Another idea behind the 80 diet 20 exercise theory is the calorie deficit that we had talked about earlier. It is basically the idea that for you to lose weight, you need to consumer fewer calories than you use. We mentioned that for you to have less, you can either cut back on calories through diet or burn more calories through exercise.

    Well, burning calories through exercise to lose weight could prove to be daunting.

    To show you why it is not practical to lose weight through exercise alone, let us use this example:

    • Let’s say that your total daily energy expenditure (TDEE) is 2,100 calories.
    • TDEE is simply the number of calories you need in a day, considering your BMR and the calories that you need for other activities.
    • 2,100 calories daily are equivalent to 14,700 calories in a week.
    • Most experts suggest cutting back your TDEE by 15% to 20 %.
    • In our example, 15% of 14,700 gives you a calorie deficit of 2,205 calories in a week.

    Now, it is not practical to lose 2,205 calories through exercise simply because you need to exercise a lot to lose a few calories. For instance, a person weighing around 80 kilograms can only burn 170 calories in a 10-minute run. Whereas, you can easily cut back 100 calories depending on your choice of food.

    How to Apply the 80 Diet 20 Exercise Theory

    The question now is, how are we going to apply the 80:20 rule? You need to cut about 80% of your calorie deficit through diet and burn about 20% of your deficit through exercise. Of course, if you are really determined about quantifying everything, you can use your BMR, TDEE, and calorie deficit to better compute what you consume. But the main point of the 80:20 rule is to focus more of your attention on diet and nutrition, and less on physical workouts.

    Remember that the examples above are simply meant for explanation – each person is different and therefore has different needs.

    So, Is Exercise Dispensable?

    Absolutely not. Exercise remains to be a vital aspect of losing weight. According to Michele Olson, Ph.D. of the Auburn University at Montgomery, Alabama, without exercise, only a portion of your weight loss will come from fat. Not exercising will drive your body to lose muscle and bone density, she adds.

    Furthermore, experts say that eating less will drive the body to resist weight loss. As you lose weight, your metabolism may slow down. You can speed it up again through working out, so exercise is still necessary.

    Key Takeaways

    With regards to losing weight, the numbers may change. Experts like nutritional biochemist Shawn M. Talbott, Ph.D., says that “weight loss is generally 75% diet and 25% exercise.”

    However, the bottom line is that many experts believe that losing weight should be more about nutrition than it is about exercise. But they also emphasize that sweating is important. After all, a workout is not just about losing weight – it is also about maintaining good cardio health and circulation, promoting bone and muscle health, and other health concerns.

    The 80 diet 20 exercise theory may be a good starting point for some people who want to lose weight. Be attuned to what your body needs, nourish it with good, clean fuel, and incorporate more physical activity.

    Learn more about Healthy Eating here.


    Hello Health Group does not provide medical advice, diagnosis or treatment.

    Medically reviewed by

    John Paul Abrina, MD

    Oncology · Davao Doctors Hospital

    Written by Lorraine Bunag, R.N. · Updated Jun 21, 2021

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