Can You Lose Weight on a Low Carb Diet Without Exercise?

Max Carmody, MSc

It is possible to lose weight on a low carb diet without exercise, and dieting is actually more important to losing weight than exercise is.

Calories and Weight Loss Basics

Weight loss ultimately comes down to calories. Calories are the energy in food. Your body always needs energy, and uses calories from food to continue working. Energy from calories fuels every action you take. Carbohydrates, protein, and fat all have calories, but no matter where they come from, the calories you eat are either stored in the body as fat, or burned as energy. Stored calories stay in your body as fat until you use them up. You can do this either by cutting the calories you take in so that your body must depend on reserves for energy, or adding more physical activity to burn more calories.

Most people know that weight loss is quite difficult to achieve and maintain. However, it is very simple in theory. Basically: to lose weight you need to burn more calories than you eat. The basic body functions, like breathing, creating new cells, and maintaining body temperature, use 50-70% of your calories daily. The rate at which your body uses calories for the basic body functions is called the Resting Energy Expenditure (REE). Your REE is determined by age, gender, genes, and body composition. So much of the energy you use is predetermined. However, the total amount of energy you end up burning each day is dependent on the exercise you get, which you can change.

Typically, you hear that cutting food intake by 3,500 calories will result in a 1 lb loss of fat. Researchers found that 3,500 calories of energy equaled roughly a pound of fat. However, this isn’t true for everyone. It is true that in general if you cut 500 calories a day from your normal diet, you may lose ½ pound to 1 lb per week. But this can be different depending on your body, your activity level, your gender, and how much weight you want to lose.

Low Carb

Carbohydrates are one of three macronutrients that the body needs to function. A macronutrient is a type of food required in large amounts to function, and the other two are fat and protein. Carbohydrates (carbs) are fiber, sugar, and starches, they are nutrients that your body uses to function. Your digestive system breaks down carbs into glucose or blood sugar, and your blood stream absorbs glucose and uses it as energy to fuel your body. There are different types of carbs. There are both simple carbs, and complex carbs. Both types of carbs provide energy, but simple carbs give your body short bursts of energy, and complex carbs take longer for your body to break down, they are a longer lasting energy source. Simple carbs include things like table sugar, fruits, and milk, and complex carbs are things like whole grains.

Low carb diets typically involve eating less than 130 grams of carbs a day. Some low carb diets, like the keto diet, are more extreme, and involve eating under 50 grams, to as low as 20 grams of carbs a day. To make up for fewer carbs, low carb diets typically increase the amount of fat, and/or protein consumed. There is no one standard low carb diet, but rather a wide variety of different diets.

Can You Lose Weight Without Exercise?

It is absolutely possible to lose weight without exercise, on any type of diet, low carb included. We always hear about the importance of exercise. And it is important. But it is much more efficient to lose weight by cutting calories than by exercising. Some studies have found that the participants tend to lose more weight by diet alone, than by exercise alone. If you want an energy deficit of 300 calories, you can either take a 3 mile run, or not eat a small bag of potato chips. Which is easier?

Often, the importance of exercise to losing weight is oversold. People are led to believe that it is more important to weight loss than it actually is. Now don’t get me wrong, it does help a little bit. And it is great for you for your general health, beyond weight loss. I exercise as much as I can these days, at least a few times a week. But I wouldn’t depend on exercise completely to lose weight.

We already know that 3500 calories is not actually always equal to a pound. But for our purposes, we’ll just pretend that it is, roughly. Let’s look at how many calories you can expect to burn in a half hour exercising. A 150 pound person can expect to lost from about 140 to 300 calories in 30 minutes of exercise, depending on their body composition, and the intensity of the exercise. Now let’s say that you are exercising every single day for 30 minutes of moderate intensity exercise. You will burn 200 calories a day, for 7 days. This is 1400 pounds. This would be equal to less than half a pound. Losing 1-2 pounds a week is considered to be generally a healthy amount for weight loss, so a lot of that would be coming from diet as well.

Importance of Exercise

Even though exercise is not vital to lose weight, it is still a good thing, and I would still recommend it. First of all, every little bit helps, and even if you do not lose weight massively faster, you are going to lose weight a little bit faster by exercising. Exercising also builds muscle mass, which speeds up your metabolism, and helps you to burn off calories quicker, even while resting.

In addition to weight loss, there are many other reasons why you should be exercising. Being active can “improve your brain health, reduce the risk of disease, strengthen bones and muscles, and improve your ability to do everyday activities. Exercise combats or helps manage various health conditions, like stroke, metabolic syndrome, high blood pressure, Type 2 diabetes, depression, anxiety, many types of cancer, and arthritis. It can even improve your mood!

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