Why is exercising the most popular type of weight-loss activity after dieting? Does it really matter that much? What does it do to your body? When people advise us to work out, do they mean cardio, stretching, weight lifting, or participating in sports? Do weight loss results depend on exercise intensity?
If you have ever asked yourself those questions, this article is for you! It doesn’t matter if you love your workout time or persistently intend to avoid exercise as a weight management activity. Knowing what happens to your body when you do sport is very important.
Let’s get started!
Table of Contents
Does working out make you lose weight?
Working out = energy expenditure = calorie burn
Working out has become a popular method for weight loss due to the fact that when exercising, your body burns more calories than in a passive or relaxing position.
And according to the nutrition law, if you burn more calories than you consume in a day (in other words, entering a calorie deficit), you start burning fat. In that sense, increasing your physical activity, in combination with reducing your calorie intake, allows you to burn more calories and achieve better weight loss results. But that is only in theory. 
Discovering movement, play and eating good food is far more fun than counting calories in and out!
It’s true that the most intensive exercises (running, aerobics, tabata, cardio in general), help you to burn more calories from physical activities, as they require larger energy expenditure. In that sense, doing high-intensity workouts seems like a promising way to improve your weight. 
Furthermore, a 2017 study published in the Journal of Health and Quality of Life Outcomes suggests that while high- and moderate-intensity workouts can significantly reduce the bodyweight of obese individuals, low-intensity exercises can also stimulate additional energy expenditure, but are less likely to support significant fat loss. 
However, the study does not specify whether the individuals who participated in the trials restricted their calorie intake.
Can you lose weight only with exercise?
A 2019 paper published in The American Journal of Clinical Nutrition suggests that effective weight loss can be achieved through a combination of reduced calorie intake (diet) and increased energy expenditure (exercise).
Furthermore, the study implied that exercising by itself is not enough to stimulate weight loss, but can be effective in weight loss support and preventing yo-yo effect, as well as weight regain. These outcomes support the results of 23 other diverse exercise training studies. 
In other words, you can try to lose weight only with exercises, but the results are unlikely to be satisfying.
Why exercise doesn’t help weight loss?
That question is wrongly but commonly asked. Exercising indeed helps you to lose weight faster when you combine it with an appropriate diet, as it increases the number of calories you burn on a daily basis. However, there is one main problem with using physical exercises as the only weight loss tool: It’s unlikely you’ll burn enough calories.
Even though we get 100% of our daily calories from food, we burn them in different ways.
Depending on our metabolism, we burn between 60 and 75% of the food we consume by simply “existing.” This is called “the resting metabolic rate” and tells us how many calories we burn in resting position. 
The body naturally uses this energy to maintain body temperature, proper organ function, blood circulation, cell reproduction, breathing, etc. And surprising or not, this accounts for the largest portion of daily energy expenditure. 
That being said, we use 10% of our daily calorie intake to digest the food we eat, and burn about 10-30% of the calories through physical activity (this is not applicable to professional athletes, as they use more energy.) Approximately 10% is needed for walking, cooking, cleaning, fidgeting, or for other regular activities, such as chores. 
And to increase the portion of energy expenditure from physical activity above 30%, you need to spend a lot of time working out every day. However, in order to prevent “over-exercising” and accumulating excess stress in your body, you should plan your weight loss journey very carefully, with the help of a fitness professional.
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What are the benefits of exercise?
As mentioned, working out can effectively support weight loss when combined with diet. But it has other health benefits that should not be neglected. According to Harvard Health Publishing, doing moderate-intensity exercises for 30 minutes a day, or high-intensity exercises for 15 minutes, can improve your health and wellbeing. 
The US Centres for Disease Control and Prevention emphasizes the following benefits of moderate-intensity exercises for at least 150 minutes per week  :
- Support weight loss and maintain weight after dieting
- Improved mental health and better mood (lower rates of depression and anxiety)
- Improved concentration and cognitive function
- Reduced risk of heart disease and heart attack
- Reduced risk of type 2 diabetes and metabolic syndrome
- Reduced risk of some types of cancer (e.g., bladder, breast, colon, kidney, lungs)
- Stronger and healthier bones and joints
- Better developed muscles
- Increased chance of living longer
Besides, a 2020 study evidenced that the benefits of increased physical activity can be related to healthier food choices and decreased appetite. Furthermore, the research results showed that the benefits of working out are unlikely to be offset by food rewards. 
Considering all those benefits, we can conclude that regular moderate-intensity exercises can significantly improve your wellbeing! And even if they are not very effective for weight loss on their own, they can help you achieve faster results when combined with a suitable diet.