Exercise More or Eat Less?

If you’re trying to lose weight, you’ve probably heard this advice: “Eat less, move more.”

Sounds simple enough, right?

But if weight loss were really that straightforward, no one would struggle with it.

Yet, millions do.

This advice makes it sound like diet and exercise are equally important for weight loss—but are they?

Is hitting the gym as effective as changing what’s on your plate?

Let’s dive into it. But first things, first.

The Science of Weight Loss

Weight loss is primarily a game of energy balance—how much energy (calories) you take in versus how much you burn.

Here’s how energy balance affects your weight:

• Calorie intake > Calorie burn → Weight gain

When you consistently consume more calories than your body requires, it stores the excess energy (primarily as fat) for future use when food isn’t readily available. Over time, this leads to weight gain.

• Calorie intake = Calorie burn → Stable weight

When the amount of calories you consume matches your body’s energy needs, all the food you eat is used up for energy, leaving no excess to be stored, or a deficit to make up for. As a result, your weight stays the same.

• Calorie intake < Calorie burn → Weight loss

When you consume fewer calories than your body requires, it uses all the energy from food and then turns to stored fat to make up the difference. This is what leads to weight loss over time.

Your body weight tends to fluctuate from day-to-day for a variety of reasons.

However, tracking the trend over weeks or months provides a clearer picture of whether you’re in a calorie surplus, maintenance, or deficit.

Gaining weight? You’re in a surplus.

Losing weight? You’re in a deficit.

Staying the same? You’re at maintenance.

How to Induce a Calorie Deficit

For any significant weight loss to occur, you need to be at a calorie deficit—eating less calories than you burn.

The body burns calories in 3 main ways:

• Basal metabolic rate (BMR): Energy used for essential body functions that keep you alive. Accounts for majority of total daily energy expenditure (about 70%).

• Physical activity: Comprises of both intentional exercise and non-intentional movements like standing, fidgeting etc. The total amount of energy burned is dependent on an individual’s daily activity level.

• Thermal effect of food (TEF): Energy used to digest, absorb and transport food. Makes up about 10% of total energy expenditure, but is dependent on what and how much you eat.

You can achieve a calorie deficit through 2 ways:

1. Decrease calorie intake by reducing how much you eat

When you eat less than your body needs for energy, it turns to fat stores as an additional fuel source.

As your body burns stored fat, you lose fat tissue, which leads to a reduction in overall body weight.

2. Increase calorie burn by increasing your physical activity

Physical activity (intentional exercise + non-intentional movements) helps induce weight loss by increasing the amount of calories you burn throughout the day.

The number of calories burned depends on both the intensity and duration of the physical activity.

The harder and longer you exercise, the more the calories you’ll burn.

Exercise vs Diet for Weight Loss

Numerous studies have been conducted to compare the effectiveness of exercise and diet in weight loss.

One significant study involved 439 overweight-to-obese women who were relatively inactive (doing less than 100 minutes of physical activity per week).

They were divided into 4 groups:

• Group 1 - Diet only (a reduction of 500-1000 kcal/day)

• Group 2 - Exercise only (45 minutes of moderate intensity aerobic exercise, 5 times per week)

• Group 3 - Combined dietary and exercise intervention

• Group 4 - Control group (no changes to their normal lifestyle)

After 12 months, the findings were quite telling.

The diet-only group had lost an average of 8.5% of their initial body weight, the exercise-only group lost an average of 2.4%, the combined diet and exercise group lost an average of 10.8%, and the control group had almost no change, with only a 0.8% loss.

The Verdict: Exercise is great, but diet is key

Both exercise and diet are effective for weight loss.

However, dietary changes appear to be more beneficial for a number of reasons:

• It’s significantly easier to eat fewer calories than it is to burn more.

For example, a large burger with fries can easily contain 700-900 calories.

To burn off those calories, you'd need to do around 1 hour of vigorous cycling or 1.5 hours of running at a moderate pace!

It’s much easier to just skip the burger than trying to burn off those calories through exercise.

This shows why trying to “out-exercise” a poor diet is often a losing battle.

• Reducing calorie intake has a more direct effect on creating a calorie deficit.

When you eat fewer calories than your body needs, you immediately create a calorie deficit.

For example, cutting 500 calories from your diet directly results in a 500-calorie deficit. The body responds to this deficit by using stored fat for energy, leading to weight loss.

On the other hand, creating a calorie deficit through exercise isn’t as straightforward.

Burning 500 calories through exercise doesn’t always equate to a 500-calorie deficit, mainly because of compensatory mechanisms.

After exercise, people often feel hungrier and may eat more than they normally would, potentially negating some or all of the calorie deficit created by the workout.

Additionally, after an intense workout, people tend to move less throughout the day. This reduces the number of calories burned through non-intentional movements like standing or walking.

As a result, the total daily calorie burn doesn’t increase as much as expected.

While exercise is essential for overall health and has numerous physical and mental benefits, calorie reduction through diet remains the most effective and efficient method for achieving significant weight loss.

That said, the best results come from combining both dietary changes and increased physical activity.

TLDR: Key Takeaways

• Make dietary changes your primary strategy for weight loss.

Start by reducing junk food, cutting down on sugary drinks, or reducing the portions of your meals.

How fast or slow you want to lose weight will determine how much you cut from your diet.

However, keep in mind that the more strict and drastic the changes, the harder it may be to stick to.

Extreme diet restrictions could also negatively impact your health.

So, ensure the changes you make are ones you can realistically maintain over the long term.

• Use exercise as an add-on to your diet changes.

While you can lose weight using dietary changes alone, increasing your daily physical activity amplifies the effects of a calorie-controlled diet, leading to even better results.

How much exercise you can do will obviously depend on how much time you can realistically allocate to exercise.

If you don’t have enough time for a structured exercise session, find ways to increase everyday movement—walk to the supermarket, take the stairs, do chores around the house.

These small movements add up and contribute to your overall calorie burn.

Thanks for reading! I hope you found something valuable :)

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