Diet vs. Exercise: What’s More Important?

diet vs exercise

Diet vs. Exercise: What’s More Important?

By: Julie Mancuso, founder of JM Nutrition, nutritional counselling service by a team of nutritional practitioners


In this post:

  • Exercise and weight loss

  • Nutrition vs. exercise: it’s not just about calories

  • Impact of nutrition on health vs. impact of exercise on health

  • Is diet more important than exercise?

  • Calories in food

  • Can you lose weight without exercise?

  • Diet vs. exercise: what the experts say


The diet vs. exercise (nutrition vs. exercise) debate

In recent years the gym fever has gripped millions, particularly here in North America. Much of this exercise craze has been perpetrated by traditional and social media who, for the better part of the last decade or two, have been bombarding us with obesity statistics and how exercise is the silver bullet that can put an end to it all.

Guess what? It can’t. It won’t. At least not by itself.

Before you scroll down the page looking for a place to leave a comment, allow me to explain why in the diet vs. exercise debate, nutrition reigns supreme.


The importance of exercise

In the diet vs. exercise debate, exercise is no doubt incredibly important for a number of reasons:

For these reasons our sports nutrition professionals and I feel that exercise should form an integral part of a healthy lifestyle, as it is in mine. There is no doubt about that.

Learn more about the importance of exercise.


Exercise and weight loss

Exercise alone, however, just doesn’t cut it.

One reason why this is the case is that people often overestimate the calories that exercise burns.

How many times have you heard someone proudly boasting that they spent an hour on the treadmill like they’ve conquered Mount Everest?


Exercise is more than calories burned

First, let’s make it clear that the nutrition vs. exercise debate is not exclusively about calories. There are many more facets to the matter. The focus here, however, will lean towards the burning of calories because that’s what we typically encounter in our practice. It’s a yardstick that a great number of people use to compare the two or use one to justify the other.

For this reason, we’ll take a closer look at this commonly used measuring system.

Related: How to Gain Muscle and Lose Fat

Exercise and calories burned

While running on the treadmill or anywhere else is a great thing, it only burns up about 300 calories in one hour, running at a moderate pace, which most of us do. Even if you do a reasonably intense interval run for the same amount of time, you may only burn 500 calories.

Other forms of exercise and calories burned in a 1-hour session, according to Fitness Magazine:

Elliptical machine: 575 calories

Weight lifting (machines or free weights) 385 calories

Walk-jog-intervals: 385 calories

Jazz dance: 305 calories

Golfing: 290 calories

Brisk walking: 245 calories

Yoga: 160 calories


Calories in food

Now that may sound like a great many calories until you compare it to its 500-calorie food equivalents:

2 of your average donuts or

1 Big Mac or

A 6-inch Meatball sub from Subway or

Low-carb slice of cheesecake from the Cheesecake Factory


Even healthier foods can be highly caloric, swiftly adding up to 500 calories:

one and a half avocados

2 cups of mashed sweet potatoes

250 grams or just over 8 ounces of salmon


That 500 calories you used up during that intensive treadmill workout loses its lustre quickly when you have one of these food items as a hard-earned treat later that day, doesn’t it?


Beware of your mindset

Indulging as a post-exercise reward

Being of the mindset that you can indulge in unhealthy (or healthy, for that matter) food or overeat because you had a great work out session will rear its ugly head very quickly, likely leading to the difficulty in maintaining a healthy weight and potentially leading to weight gain over time.

Related: Nutritionist and dietitian counselling for weight loss

And it’s not just about weight either. The consumption of unhealthy food can affect virtually every aspect of your life.

Indulging as a means for post-exercise refuelling

What’s more, there are also those who try to justify overeating or having a post-workout treat by seeing the consumption of extra-calories as refuelling. And at times that is the case. If you’ve played a competitive basketball game or took part in a high-intensity dance class for 60-minutes or so, then the need for some sort of refuelling is likely and even necessary.

Related: Learn about endurance nutrition misconceptions.

Often times, however, all those extra-calories are not needed, particularly when they come from foods that contain very few nutrients.

Refuel enough to help your body recover and repair, but no more. And make sure to refuel with proper, nutrient-rich food and drink.

In addition, exercise can trigger a larger appetite, leading to overeating and effectively the taking in of more calories than have been burned off by working out. 

Related: Workout Supplements: What Supplements Should I Take?


The impact of exercise on your health

Let’s take a look at a practical example of this diet vs. exercise (nutrition vs. exercise) battle for supremacy.

You’re disciplined and attend the gym 5 times per week for 1 hour (30-minute cardio session or class and 30-minute weight training).

In 4 weeks or 1 month, you would’ve made 20 visits to the gym. In other words, you’d have 20 opportunities to make a positive impact on your health and well-being.

Even if you go to the gym every day, and let’s face it, few of us do, that’s about 30 opportunities per month.


The impact of diet or nutrition on your health

Now let’s put this into perspective and look at food consumption:

Let’s suppose you eat 3 meals and 1 snack per day, potentially more. But let’s stick to 4, for argument’s sake.

That’s 4 separate opportunities to make a positive impact on your health and well-being in one day. And this doesn’t include other potential opportunities: treats, going out, take out food, late evening snacking, parties, movie theatre, etc.

After one month, you would have had at least 120 opportunities to affect your health. That’s 4 times more than exercise. It’s incredible when you stop and think about it.

And for those of you who are quick to point out that you don’t eat 4 times per day because you fast or skip meals, even if you eat twice per day, you will have 60 chances to make an impact with nutrition as opposed to only 30 with exercise. That’s still twice as much.


Diet vs. exercise, and sedentary lifestyles

There’s also another important point worth mentioning in the nutrition vs. exercise debate and that’s our sedentary lifestyles.

Sure, there are people who exercise regularly and strenuously, as well as those who burn inordinate number of calories by doing work that requires a great deal of physical labour. But for many of us, our jobs consist of too much sitting around.

And things aren’t much better outside of work. First we sit too much at work in front of computer screens, we then stand around watching our kids take part in sports and then we wind down at the end of the night in front of the tv. That’s certainly no recipe for a healthy lifestyle.

Some of us do manage to muster enough energy to pop into the gym for an hour a couple of times per week. And that’s great.

But can a one-hour session of exercise, no matter how strenuous, make up for the 8 hours we sit at a desk and a further 1 or 2 hours we spend in front of the TV? Impossible.


Diet vs. exercise: why exercise alone is not enough

Studies show that the push for increased physical activity levels in recent years has not reduced the obesity rate at all. From this the conclusion is clear: it’s the food we eat that caused this epidemic in the first place. 

Sure, you can say I’m biased because I am in the nutrition service business, but the numbers and facts don’t lie.

And that’s why I’m still left baffled as to why the first thing many people do when they reach a breaking point and want to make sudden, healthy changes in their lives is to join a gym. Regular gym attendance and exercise should accompany healthy, balanced eating habits, not be a replacement for them.


Nutrition vs. exercise: prioritize nutrition

That, in my opinion, should be the second thing you do. The priority should be improving nutrition, whether on one’s own or with the assistance of a nutritionist or dietitian.

And if you still aren’t convinced, then take it from, who claim that if you don’t already have sound nutritional knowledge and want to engage in bodybuilding, then improving your nutrition should become your priority, before training. 


Diet vs. exercise: Why is nutrition important?

I’m not going to launch into this long list of reasons why nutrition is important. But I will summarize in brief.

  • Reduced risk of many chronic diseases: type 2 diabetes, heart disease, liver disease, kidney disease, hypertension, osteoporosis, some cancers et al.
  • Maintenance of a healthy weight
  • Reduced risk of obesity
  • Negative impact on our children who learn their eating habits from their parents
  • Improved sense of well-being
  • Increased energy
  • Better sleep
  • A boosted immune system
  • Fewer visits to the doctors
  • Improved mood
  • Sharper brain function
  • Better athletic performance
  • And so on


What you don’t eat is more important

So what should you eat then?

This a question that’s probably on most people’s minds, at least those who are ready to make positive, lasting changes to their eating habits.

But here’s an important idea to keep in mind: what you eat is less important than what you don’t eat.

Be careful of self-sabotage

I cannot begin to tell you how many people regularly and inadvertently sabotage their own nutrition, health and wellness goals by not adhering to this principle.

You can eat all the healthy food you want and attending the gym may be a well-embedded habit, but you can seriously undermine your fine effort by habitually giving in to unhealthy temptations.

A donut or two on your coffee break, a handful of cookies in the evening while watching your favourite Netflix show and a couple of Margaritas on a sunny summer day are insidious, and lead to the consumption of many extra-calories, let alone mounds of sugar, preservatives, trans fats et al.

All these small indulgences add up fast and, as mentioned earlier, are difficult to burn up through exercise. Over time, extra, unburned calories can contribute to weight gain or at least the difficulty in maintaining a healthy, desirable weight.

This often leaves those who feel they eat generally healthily and exercise regularly frustrated and baffled. Some even resort to strict diets that revolve around deprivation in one way or another, in an attempt to rectify the situation. But that’s getting away from the root of the problem.

This is not to say that you cannot indulge a little here and there. But make sure your treat is, as the definition says, a treat, or something out of the ordinary.

Of course, matters pertaining to weight management are complicated, multi-layered and fraught with weight loss obstacles. There’s a great deal more to the issue than just calories in and calories out. And this is typically what we delve into in our weight loss program.

Related: Weight Loss Coaching


Low- vs. high-quality food

According to Harvard Health, it’s also important to know the difference between low-quality vs. high-quality food, and plan your meals accordingly.

The former being highly refined, processed, often low in nutrients as well as high in sugar, sodium and trans fats. The latter, one other hand, is minimally or not all processed and nutrient-rich. Interestingly enough and barring a few exceptions, low-quality foods are often highly caloric when compared to high-quality ones.

Related: To Lose Weight, Eating Less Is Far More Important Than Exercising More, The New York Times


Food and calories

As I said earlier, many people tend to overestimate the number of calories burned by exercise while grossly underestimating how many are consumed through eating food.

Here are some examples of typical foods and their approximate (rounded) calorie count:

  • Bagel: 290
  • Salted butter: 100
  • 1 chocolate chip cookie: 60
  • Ice-cream (vanilla, 4 ounces): 145
  • 1 slice of pepperoni pizza: 300
  • 1 medium baked potato: 160
  • 2 tablespoons of ranch salad dressing: 145
  • 1 glass (5-ounce) of cabernet sauvignon: 125 (Read about wine and weight loss.)
  • Spaghetti (cooked, 1 cup): 220
  • Sauce (marinara, 4 ounces): 90

Source: USDA


Very low-calorie foods:

  • Apple (medium): 70
  • Beets (1 cup): 60
  • Black beans (½ cup): 115
  • Boneless skinless chicken breast (3 ounces): 90
  • Broccoli (1 cup): 30
  • Carrots (1 cup): 50
  • Cauliflower: (1 cup): 25 calories
  • Cod (3 ounces): 70 calories
  • Egg (large): 70
  • Red Bell Pepper (1 cup): 45
  • Tomatoes (1 cup): 25 calories
  • Zucchini (1 cup): 20 calories

Source: Healthline


The goal is to reduce lower-quality, refined, processed, high-carb and highly caloric foods, while introducing better quality, nutrient-rich, low-carb and lower-calorie ones. You may need to incorporate meal planning and prepping strategies, especially at first. 

Once this healthy habit is established for a sustained period of time, then you can start devoting more of your attention to weight training and increased exercise.

Related: Nutrition myths debunked

Nutrition vs. exercise? Try nutrition and exercise

That is not in any way to say that you shouldn’t exercise while you’re making an adjustment to your eating habits. Not at all. Quite the opposite, I encourage it. After all, exercise will cause you to burn more calories (along with all the other previously mentioned benefits), increasing the chance that you will feel better. Just don’t be of the mind that exercise will be your saving grace.

Besides, proper nutrition makes exercise more likely. If your body is fuelled properly for a sustained period of time, it is likely to feel energized, leading to greater likelihood that you will actually exercise.

In addition, if you regularly provide your body with vital nutrients it needs, then it is likely that you will exercise more effectively, have greater stamina leading to longer workouts and allow your body to recover properly after exercise. This, in turn, will lead to healthy and sustainable weight loss, gained muscle and improved athletic performance, making you feel and look better.


Diet vs. exercise: Can you lose weight without exercise?

In short, yes.

People can lose weight without exercise. Some of our clients, who don’t want to, can’t or don’t have much time for exercise, do shed pounds just by making fundamental changes to their eating habits and mindset.

No deprivation. No starvation. Just properly designed, nutritionally balanced meal plans based on one’s food preferences. That’s key, for many people. They are more likely to stick to healthier eating habits over the long-term if they like what they’re eating–just in the right portions and proportions.

Avoiding sugar, refined, high-carb food and drink is a must as well.

It’s also important to analyze health and family history, triggers, cravings and emotional eating–common areas were people can falter. But with support from friends, family and your health practitioners, anything is possible.

Related: Metabolism 101


Diet vs. exercise: What other experts say

I’ll leave you with the opinions of other experts on what’s more important diet or exercise:

The American Dietetic Association, now known as the Academy of Nutrition and Dietetics, underscores the importance of nutrition by stating that it’s almost impossible for people to reduce caloric intake and lose weight without managing and reducing what they eat.

WebMD: “All the exercise in the world won’t help you lose weight if your nutrition is out of whack.”

US News Health: “The reality is that the only way to lose weight is to burn more calories than you take in, which is nearly impossible to do unless you change your eating habits.”

US Centres for Disease Control and Prevention study verdict: Diet is far more important than physical activity when it comes to losing weight.

CNN Health: “What you omit from your diet is so much more important than how much you exercise.”

Mayo Clinic: “…cutting calories through dieting is generally more effective for weight loss.”


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JM Nutrition is a nutritional counselling and consulting service by dietitians and nutritionists in Toronto., with other locations in Ontario, Vancouver and Halifax. We offer in-person appointments and nutritional counselling with online dietitian

Author: Julie Mancuso

Julie Mancuso

Julie Mancuso is a graduate of the University of Toronto, founder and owner of JM Nutrition, a nutritional counselling service by registered dietitians and nutritionists. For 15+ years, JM Nutrition has helped thousands reach their health, wellness and nutrition goals. Julie and her team regularly lend their expertise to a variety of health publications such as Reader's Digest, Livestrong, Business Insider, Food Network, Today's Parent, MyFitnessPal, Toronto Star, Elle Magazine, Best Life, Weight Watchers and many more.