The Science Behind Weight Loss

Science Behind Weight Loss

Does 3,500 Calories Really Equal 1 Pound?

Weight loss, in theory, sounds incredibly simple.If 3,500 calories equals one pound, then creating a calorie deficit of 3,500 calories will result in weight loss! But as society has proven, and most of us have experienced, weight loss is the farthest thing from simple math. In today’s article, we are going to talk about why this is.

We’ve all likely heard the teaching that 1 lb. of body fat = 3,500 calories. As it turns out, this isn’t true. The 3,500 calorie number is based on outdated and faulty science dating all the way back to the 1950s. In 1958, researcher Max Wishnofsky, MD, calculated that 1 lb. of body fat stores approximately 3,500 calories of energy. This appealing simple number stuck around despite the fact that it’s over 50 years old. Fortunately, science recently acknowledged that this number fails to account for a variety of factors. In 2012, the American Society for Nutrition and the International Life Sciences Institute refuted this claim in a jointly issued consensus statement.

Decreasing your intake by 500 calories/day so that you drop 1 lb. in a week isn’t how weight loss works. At best, this rule seems to work for short term weight loss but in the long term, it doesn’t hold water. One of the reasons why is because the 3,500 calorie rule fails to account for the metabolic changes that take place as you lose weight. Hence the reason why individuals wanting to lose weight may be successful at first but eventually plateau.

Meet Frank

To put things into simpler terms, let’s meet Frank. Frank is a 48 year old man, at 5’7” weighing around 200 lbs. Frank could definitely lose some weight. We’ll say that Frank’s basal metabolic rate, or the rate at which his body uses energy when at rest, is 3,300 calories. This means that on a day when Frank isn’t doing any form of exercise, he only needs 3,300 calories to maintain his body’s functions. Currently, Frank eats 4,000 calories. Given these numbers, we can pretty easily see why Frank slowly gained weight over time. In order to maintain his weight of 200 lbs., Frankonly needs to eat 3,300 calories each day. Now if Frank wants to drop one pound per week based on the 3,500 calorie rule, he needs to create a deficit of 500 calories each day. This means that he should only eat 2,800 calories per day.

As stated earlier, the 3,500 calorie rule may work for Frank initially. The calorie drop in comparison to Frank’s basal metabolic rate will mean that the body will have to rely on its energy stores (fat) to maintain Frank’s size. In other words, Frank will eventually lose some of his excess fat stores. But as Frank keeps consuming the 2,800 calorie diet, he will eventually plateau. This is because as Frank drops weight, he needs fewer calories to maintain his less-heavy self. So while Frank’s basal metabolic rate began at 3,300 calories/day, it could drop to 2,900 calories/day due to the weight loss.

Weight Loss is Not Linear

By no means is this article meant to be a detailed explanation of all the flaws behind the 3,500 calorie rule. That will be discussed in the article, The Mathematics of Weight Loss.This article is simply meant to discuss the science on which some weight loss programs are built, and in this case, how many of these weight loss programs are built on flawed science. All of this is to say that while weight loss is taught as a linear function, it is everything but that. Weight loss is NOT linear. And unfortunately, this newfound knowledge has not been widely adopted for clinical weight management or used to inform policy discussions. But just because it hasn’t been widely adopted doesn’t mean that you can’t apply it to your daily life.

Understand that human physiology is complicated and ever changing. If you are on your own weight loss journey, don’t obsess over the scale especially if you know that you are doing everything you can to live a healthier life. Steady, sustainable weight loss takes time. It takes month after month and year after year of dedicated hard work. Despite what the media tells us, it’s not fair or realistic to expect that you can lose 8 lbs. in one week.

The fact of the matter is that weight loss isn’t just about the scale, it’s about making lifestyle improvements that increase longevity and decrease mortality. Weight loss should be far deeper than what you see when you look in the mirror, there should be a goal for improved health. For more information on how to effectively lose weight, read 5 Habits that Boost Weight Loss.