Here’s how many calories you have to burn to lose a pound of fat: In 1958 Dr. Max Washnofsky wrote a paper published in the American Journal of Clinical Nutrition stating that a pound of body weight is equal to 3500 calories. While this is a correct estimate in a lab, (imagine a hunk of fat over a Bunson burner) it is not so in the human body which is a complex system.
The reduction or burning of 3500 calories might be accurate for each of the first few pounds you lose, but after that it’s a little more complicated.
That’s because the actual number of calories that you need to burn to lose a pound of fat depends on a number of variables including: your metabolism, amount of exercise, and your diet. (carbs, fats, proteins)
That means the idea that by eating 3500 fewer calories you will lose a pound of weight is largely a myth.
Why You Have to Burn 3500+ Calories to Lose a Pound
Popular health websites will tell you that because there are 3500 calories in a pound of fat, each pound of weight loss is just simple math.
For instance, they will claim that reducing your caloric intake by 500 calories each day, you’ll lose a pound after one week. (500 x 7 = 3500)
That’s pretty accurate during your first week, but increasingly less accurate as time goes on.
Here’s the important thing to understand: your body is good at adapting to change. As you reduce the number of calories you intake each day, your body starts to make adjustments to work with what it’s given.
That means if you are starting a diet, the number of calories you need to burn (or cut out from your diet) each day to lose one pound is very different on day 1 compared to day 300.
Really? That’s kind of frustrating!
It May Require Burning Up to 7000 Calories to Lose a Pound of Fat!
After you start a diet, your body begins to adapt to your lower daily caloric intake in a process called, “metabolic adaptation.” That means that while on day one of your diet it may require that you burn (or not eat) 3500 calories to lose a pound, but on day 300 it will be about twice that. This means that after being on a diet for a year, you’ll have to burn about 7000 calories to lose a pound!
That’s why when you set a goal weight and begin a diet, the first pounds are easier to lose than the last ones. In a way, it’s a lot like running a long-distance race, like a 10k. That first kilometer isn’t so bad, but last one is a lot harder!
It’s why long-term weight loss is hard, and also why few people are able to lose weight after being on a diet for a year.
*Interesting: How our ancient genes make us fat
OK, How Many Calories Do You Need to Burn / Restrict for Each Pound of Weight Loss?
Since burning 3500 calories does not usually result in a pound of weight loss, how do you determine how many calories you have to burn or restrict to lose a pound of fat?
While the 3500 calories number is pretty accurate during your first week of weight loss, there are better ways to estimate how many calories you need to burn to lose a pound in subsequent weeks. We recommend using the Body Weight Planner from the National Institutes of Health.
It will give you a much more accurate estimate based on weight, gender, age, height, and daily activity level.
It also allows you to set a goal weight and on what date you’d like to achieve that goal. From that information, it will give you a number of calories per day that you should eat to reach your weight loss goal.
For me, a tall, active, 41 year old man, I got these results:
So, in my case losing a pound a week over the course of 6 months (24 pound weight loss goal) meant a reduction of 900 calories per day, or 6300 calories in a week. Very different than the widely reported “3500 calories to lose a pound of fat” myth.
Of course, if you are a shorter woman of a different age, your daily calorie goal for weight loss will be different. So, if you’re wondering, “how many calories do i have to burn to lose 5 pounds a week,” the answer is, “it depends.” The actual number of calories you’ll need to burn or restrict from your diet to lose each pound will vary based on factors including your height, weight, gender, and activity level.
That’s why most diets, both free and commercial, (like Weight Watchers and Nutrisystem) don’t use calories to measure or predict weight loss. It’s also why they include apps or use a point system that give you a more accurate idea of the weight you can expect to lose through burning or reducing calories.
You should also consider that figures of how many calories you burn per hour during exercise can vary widely. For instance, a 125 pound woman on a stair-stepper for an hour might burn 360 calories, while a 185 pound man burns 535. That’s a big difference!
The Number of Calories You Need to Burn to Lose Pounds Isn’t Simple Math
“A pint’s a pound, the world around” – Popular saying
(But losing a pound of fat is more complicated!)
Well, as you can see, there’s no one answer to the question of how many calories you need to burn or omit from your diet to lose pounds. Sure, that first pound may be the popular number of “3500 calories,” but it’s misleading because no one has a weight loss goal of one pound!