Diet vs. Exercise: Which Is More Important for Weight Loss?

Sport & Activity

Is regular exercise more important than a healthy diet? That depends on your goal. Here are the pros and cons of focusing on exercise vs. diet.

Last updated: 27 April 2022
6 min read
Diet vs. Exercise: Which is More Important for Weight Loss?

You may have heard the phrase "You can't out-exercise a bad diet", and it's true (mostly). If you're overeating junk food and not fuelling your body with nutrient-dense foods, you won't be seeing results. No matter how much you're training.

But the age-old diet vs. exercise debate is an over-simplification. In truth, combining good nutrition and regular physical activity is the best way to bring about change in your life. And it's not just about weight loss. There are so many more physical and mental health benefits to eating well and moving your body more.

What's More Important for Weight Loss: Diet or Exercise?

All too often, the effectiveness of exercise is only considered within the boundaries of weight loss. What are the best workouts for weight loss? How many times a week do you need to work out to lose weight? How many calories can you burn? These types of questions only consider one outcome: change in body weight.

Physical activity does have notable benefits if you have weight-loss goals. It contributes to your total daily energy expenditure (TDEE), which is the amount of calories (energy) you burn in a day. Your TDEE is based on a number of factors, including:

  • Age
  • Height
  • Weight
  • Sex
  • Activity level
  • Body composition

Your TDEE is important because if you create a calorie surplus (you eat more than you need), you'll gain weight. If you create a calorie deficit (you eat less or burn more), you'll lose weight.

This has led many people to assume that if you want to lose weight, you just have to exercise more. But that's not exactly true.

Is Exercise Better Than Diet for Weight Loss?

Exercise only contributes 5 percent to your TDEE, known as exercise activity thermogenesis. If you're eating more than your TDEE, you'll gain weight, even if you're working hard in the gym. You might burn 500 calories during your workout, but you're overeating by 1,000. You're chasing your tail.

A 2012 randomised controlled trial (the gold standard of research) that lasted a year looked at whether diet, physical activity or both combined was most effective for weight loss. The researchers found that the average weight loss was highest in the diet and exercise group (10.8% of body weight), compared with diet (8.5%) and exercise (2.4%).

But that doesn't mean you should deprioritise exercise. Exercise has benefits that go beyond weight loss, and studies show that when a good diet is combined with regular exercise, the body is healthier and weight loss is maximised over the long term. Here are some other benefits of exercise that make it such a winner.

The Unique and Unparalleled Benefits of Exercise

  1. 1.Boosted Metabolic Rate

    We know we said that exercise only contributes to 5 percent of your TDEE, but there's a bit more to it. When you build muscle through exercise, you can actually boost your TDEE. Muscle is more metabolically active and contains fat-burning enzymes. This means it uses more calories while at rest, which increases your metabolism.

  2. 2.Improves Mental Health

    Numerous studies have found that engaging in a regular physical activity routine helps to alleviate depression, anxiety, stress and other cognitive or mood-related conditions. One study observed the effects of exercise on rates of depression by asking a group of participants to attend exercise classes for ten weeks. The researchers found that the intervention group experienced a 30 percent decline in depression.

  3. 3.Slows Down Ageing

    According to research, from the age of 30, we lose up to eight percent of our muscle mass every ten years. A loss of muscle mass results in reduced mobility and strength, poor balance, a decreased metabolic rate and accelerated ageing. Exercise builds muscle mass and bone density to keep us physically younger.

  4. 4.Lower Disease Risk

    Regular exercise reduces your risk of developing cardiovascular disease like stroke and heart disease, as well as obesity and type II diabetes. This is because exercise improves insulin sensitivity, lowers blood pressure, improves leptin sensitivity, strengthens heart and lung capacity, reduces blood clots and helps maintain a healthy weight.

  5. 5.Stress Relief

    Exercise is a powerful stress reliever. When we exercise, endorphins and brain-derived neurotrophic factor (BDNF) are released. These feel-good, brain-boosting molecules work to alleviate stress at a biochemical level.

    Plus, humans are designed to move. It's in our DNA. There's something about getting energy flowing through exercise that can help you become more present. A study published in the journal Acta Psychologica found that going on a one to two mile run improves your mood, decreases stress and boosts cognitive performance more than a meditation session is able to.

  6. 6.Cognitive Enhancer

    When you get your blood pumping during a workout, you also increase blood and oxygen flow to the brain. This helps it perform better. The hippocampus, the region of the brain associated with learning and memory, actually increases as a result of regular exercise. If you're fighting through brain fog, get moving!

  7. 7.Improved Cardiovascular Health

    The more you push yourself physically, the stronger your cardio system gets. Your heart and lungs will become more efficient at transporting oxygen and blood around your body. Your vital organs and muscles will get healthier and work optimally.

  8. 8.Social Benefits

    If you've ever tried a group workout class or joined a sports team, you'll notice that the exercise part is just one of many benefits. You'll also enjoy connecting socially with like-minded people. Exercise can combat loneliness and introduce you to people with similar interests.

  9. 9.Confidence Builder

    You build confidence in yourself when you make a commitment to bettering yourself and you actually stick to it. Exercise is one of the easiest and most effective ways to do that. Set an exercise goal and decide every day that you can do it. This helps to build confidence and assurance in your abilities, which transfers into other aspects of your life.

  10. 10.Fights Inflammation

    During a tough workout, you put your body under brief periods of stress and inflammation. To recover, your body triggers a powerful anti-inflammatory response like increased antioxidant production.

Eat Well and Exercise Often

The bottom line when it comes to exercise vs. diet is that it's not all about how many calories you burn or what is best for weight loss. There are so many other factors that affect your health and well-being. Your diet provides fuel for your body to function and perform. Exercise helps you feel good mentally, physically, emotionally and socially.

Whether you want to lose weight or just feel good, combining exercise and a good diet will have the most radical effect on your life.

Originally published: 18 November 2021

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