Lifestyle modifications are necessary for a healthy and successful weight loss and its maintenance. For most people, these modifications involve a healthier diet and regular physical activity. Exercise and diet are dubbed crucial for people who want to drop pounds. And they are! But what’s more important? Is diet more significant than exercise or vice versa? The answer to these questions is in the post below. Read on to learn more.

Diet vs. Exercise 

The role of diet and exercise is a subject of many studies and it’s safe to expect a lot more of them in the future. In fact, a great deal of research was dedicated to comparing the importance of diet versus exercise for effective weight loss. Below, we’re going to discuss their findings. 

A year-long, 4-arm randomized study from the August 2012 issue of the journal Obesity aimed to compare the effectiveness of diet, exercise, a combined approach, and no lifestyle modifications for weight loss. Scientists enrolled 439 overweight-to-obese postmenopausal sedentary women into the study. 

Some women consumed a calorie-reduced low-fat diet, others practiced moderate-intensity facility-based aerobic programs, the third group combined both exercise and diet, while the fourth group didn’t have any lifestyle changes. Subjects followed their program for 12 months. At the end of the study period, the average weight loss for the diet group was 8.5%, for the exercise-only group 2.4%, the combination group 10.8%, and the last group 0.8%. Waist circumference, BMI, and body fat percentage in participants were similarly reduced. Based on these findings the scientists concluded that a combination of diet and exercise worked the best for weight loss (1). 

In the combination group, subjects had a caloric deficit of 500-1000 kcal/day and 45 minutes of moderate-intensity physical activity five days a week. Scientists also explained that the effectiveness of diet and exercise programs depends on adherence. The more subjects adhered to their programs, the more weight they lost. Moreover, they revealed exercise had an important effect on maintaining lean body mass that didn’t occur with diet alone.

Moving on, the October 2014 issue of the Journal of the Academy of Nutrition and Dietetics published a review which explored the clinical effectiveness of diet-only or physical activity-only programs with at least 12 months follow-up. The review included eight studies with a total of 1022 participants the majority of whom were women. Weight loss is similar in the short-term for diet and combined approach, but in longer-term weight loss is increased when diet and physical activity are combined, the study shows (2).

When comparing the effectiveness of diet and exercise for weight loss it’s also useful to mention some pieces of research that indicate the latter is more effective. A study from 2015 found that protocols utilizing exercise are more effective than those relying on a hypocaloric diet alone. The same research also confirmed that a combination of diet and exercise works best for weight loss and reduction of body mass and fat mass. The exercise was also found to be more beneficial for insulin sensitivity, lipid management, and hormonal balance (3).

Why is Diet Considered More Significant?

As you can see, studies tend to show that diet is more significant for weight loss than exercise at least in the short-term. We’re always told to work out regularly so it’s impossible not to wonder why diet is more important.

To explain the significance of diet it’s important to address the cornerstone of weight loss – energy expenditure. It all comes down to how many calories you burn during the day as opposed to the amount you consume. The main components of energy expenditure include (4):

  • Resting (basal) metabolic rate – the energy used for basic functioning when the body is at rest
  • Thermic effect of feeding – the energy used to break down food
  • Thermic effect of activity – the energy used in physical activity

Generally speaking, we have very little control over our basal metabolic rate. That being said, basal metabolic rate accounts for 60% to 75% of daily energy expenditure. About 10% of daily energy expenditure accounts for the thermic effect of feeding (TEF). The most variable component of your energy expenditure during the day is the thermic effect of activity (TEA). 

Physical activity can constitute 15% to 30% of daily energy expenditure and it doesn’t include exercise only. You see, this aspect of daily calorie burning also includes physical work, muscular activity, even fidgeting and shivering. It’s useful to bear in mind that physical exercise can influence both basal metabolic rate and TEF.

The thing here is that your diet accounts for 100% of your daily energy intake. You are in charge of the foods you eat i.e. how much energy you’ll consume. On the other hand, exercise plays a role in up to 30% of the number of calories you burn. Take a moment to compare them. The discrepancy is big, isn’t it?

The secondary role of exercise in weight loss, in terms of effectiveness, is down to its inability to generate enough energy expenditure to create negative energy balance to the extent possible with caloric restriction (5).

Exercise May Undermine Weight Loss

We exercise to stay in shape, contribute to energy expenditure, and tone our body. But it’s also useful to mention exercise may undermine weight loss if we’re not careful. How? You see, the quantity of food you consume is connected to your physical activity levels. Many people eat more when they’re more active. On the flip side, when you don’t move much you may eat less. 

One study showed subjects seemed to increase their food intake following the exercise. The increased food intake was due to hunger, but also because they believed they burned off a lot of calories (6). Evidence also shows people tend to overestimate the number of calories they burned during exercise (7). As a result, they ate more.

It’s important to clarify that exercise doesn’t hamper your weight loss, per se. Physical activity doesn’t undermine weight loss because it’s bad for some reason, it isn’t. The problem here is our false perception of energy expenditure after exercise combined with unhealthy habits to eat more.

Let’s not forget that some people tend to slow down after a workout i.e. they lose less energy on random activities throughout the day (8). They may also opt to lie down to get some rest, use elevators or escalators instead of stairs, drive more and walk less, among other things. These are called compensatory behaviors. We behave this way because we believe exercising for 45 minutes is enough to burn a lot of calories and it’s not necessary to do anything else. In fact, many people believe their energy expenditure depends on exercise alone. As seen above, it doesn’t. These wrong perceptions don’t allow us to get the most out of exercise and explain why relying on physical activity alone may undermine weight loss. Of course, it doesn’t have to be like that if you’re careful and strive to be more active throughout the day despite exercise.

Do You Need to Exercise to Lose Weight?

Upon reading that diet is more significant for weight loss than exercise, it’s easy to conclude you shouldn’t work out to slim down. That’s not true, however. Cutting calories promotes weight loss more effectively than exercise, but the combination of both is more effective. It’s also healthier. You see, the idea of cutting calories for weight loss may prompt someone to try crash dieting. 

Crash diets are low-calorie eating programs that people follow for a few weeks or months. Some of these diets may provide rapid weight loss i.e. short-term results mentioned above. However, as soon as you stop dieting you risk regaining weight and even more. In most cases weight, regain happens within six months (9).

That’s exactly why exercise is so significant and you shouldn’t underestimate it. For successful weight loss more exercise equals greater energy expenditure. According to the CDC, while caloric restriction accounts for most weight loss the only way to maintain it is to exercise regularly (10). Regular workouts could prevent weight regain that would otherwise happen after ceasing a caloric restriction diet. 

The benefits of exercise are far too significant to neglect this lifestyle adjustment. After all, physical activity can lower blood pressure, reduce cholesterol, and even protect you against cardiovascular diseases.

In other words, a combination of diet and exercise is the most effective approach for successful weight loss and its maintenance.

How Many Calories to Eat to Lose Weight?

While it’s a well-known fact caloric deficit is necessary for weight loss, this subject is still largely misunderstood. You do not have to starve yourself to slim down. At the same time, you do not have to follow crash diets that would only lead to the yo-yo effect and weight regain. Instead, you may want to reduce calorie intake wisely. The number of calories to eat or burn is not the same for everyone due to our basal metabolic rate. It’s also not the same for men and women. 

Generally speaking, a moderately active woman, between the ages of 26 and 50, needs to consume about 2000 calories to maintain her weight. That woman needs to reduce her calorie intake to 1500 per day in order to lose 1lb (0.45kg) a week.

On the other hand, active women who walk more than 3 miles a day need to consume 2200 calories to maintain weight. Their daily calorie intake should be 1700 a day to drop 1lb on a weekly basis.

Women who are 50 or older need about 1800 calories a day to maintain their weight. To lose 1lb per week they need to eat 1300 calories a day.

Men usually need more calories than women. For instance, a moderately active man who is 26 to 50 years old needs to consume 2600 calories a day to maintain weight. His calorie intake needs to drop to 2100 calories to lose 1lb a week. On the flip side, active men who walk more than 3 miles a day require 2800-3000 calories for weight maintenance. That means they generally need to eat about 2300-2500 calories a day to lose 1lb every week. Men who are 46-65 years old usually need 2400 calories a day for weight maintenance (11).

How Much Exercise Do I Need to Lose Weight?

The exact amount of exercise for an effective weight loss may vary from one person to another. It depends on several factors including current physical activity levels, fitness level, overall health, diet, among other things. Generally speaking, you should aim to get at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity per week. Try not to do it all at once. Instead, you need to spread out the workouts during the course of a week. 

While cardio is crucial for weight loss and energy expenditure, you shouldn’t neglect strength training. Ideally, you should practice strength training at least twice a week. 

To achieve healthy weight loss, you should step up your workout and physical activity routine. The best scenario would be exercising 30 minutes a day (12). But, keep in mind that exercise is not a replacement for other forms of physical activity during the day. Even though you exercise regularly, you should still aim to be more active. Instead of elevators and escalators, try using stairs. Walk whenever you can. Try to avoid being sedentary. All these healthy practices can reduce compensatory behavior and support your weight loss.

Diet Tips for Weight Loss

Most people who want to slim down opt for restrictive fad diets that may do more harm than good. Since diet is crucial for successful weight loss, these tips will help you out (13, 14, 15, 16):

  • Consume fiber-rich foods 
  • Avoid added sugar
  • Don’t skip meals
  • Focus on healthy fats such as olive oil
  • Try the Mediterranean diet
  • Avoid watching TV while eating
  • Opt for homemade meals
  • Start your day with a protein-rich breakfast
  • Stay hydrated throughout the day
  • Cut back on refined carbs
  • Eat whole foods
  • Avoid starving yourself or limiting your diet on a few food options only
  • Eat healthy snacks such as carrot or celery sticks

The goal is to think of diet and exercise as integral components of a healthy lifestyle. Sometimes our attitude is the problem as we tend to consider diet and exercise as punishments. When we make them a part of our lifestyle, it’s easier to adopt a healthier perspective and stick to them for a long time.


Diet and exercise are described as crucial for weight loss, but one approach has to be more important than the other. Studies show that for short-term weight loss caloric restriction is more effective. However, that doesn’t mean exercise is useless. In fact, most studies confirm the combination of diet and exercise is most effective for both weight loss and maintenance. 

Exercise can help prevent weight regain, but also tones your body as you’re slimming down. So if you’re looking for the most effective way to slim down and maintain weight loss, make sure to combine a well-balanced diet with regular workouts.


















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