Weight Gain after Bariatric Surgery:
Why It Demolishes the Widely Accepted Theory That Calories "Count"

Weight gain after bariatric surgery should not happen, according to the traditional theory about on what makes us overweight.

But it does, and it does with more frequency than most people realize. This essay will take a look at some of the implications.

First of all, some background on bariatric surgery.

The National Institutes of Health recommends that morbidly obese people (BMI 40.0+) consider bariatric surgery to reduce the capacity of the stomach. Typical procedures include:

  • banding - this squeezes the stomach to a smaller size with an implanted band.
  • gastric bypass - a surgeon literally slices and stitches the stomach to make it smaller, so it can only handle a reduced volume of food.

According to industry figures, patients can expect significant weight loss over the first year or so. For instance, if someone weighs 400 pounds, perhaps he or she can lose 100 to 150 pounds within a year or two due to the imposed caloric restriction.

But interestingly, weight gain after bariatric surgery can and does occur.

In a March 2008 ABC News article, the author quotes Dr. Daniel Jones of the Beth Israel Deaconess Medical Center in Boston: "we know that 5% or maybe even more of these patients over time can regain weight."

Another physician quoted, Dr. Anita Courcoulas of the University of Pittsburgh Medical Center, says: "most patients experience something I call “The Creep.”…They creep up another 5 to 10 pounds. 80% will experience this creep and level out again, but about 20% will continue to creep up.”

Let’s pause and consider the implications here.

A surgery physically limits the amount of food that can be put into the stomach. It causes temporary weight loss, but over time, this weight loss tends to erode. What’s going on? Why would this happen at all? What can be done to stop it?

To begin to address these questions, we need to understand the conventional theory underlying nearly all reducing diets. The theory sounds like blindingly obvious common sense: cut calories and exercise more, and you will lose weight.

If you stop up the stomach, you cannot eat as much, so this should help you lose weight. As obvious as it gets, right?

Why we think this way

We get the idea that calories matter from something called the Energy Balance Equation. This derives from the First Law of Thermodynamics and tells us the following:

Energy we store = Energy that comes into our bodies - Energy that leaves our bodies

The shorthand version is:

Amount of fat we store = Calories In - Calories Out

In bariatric surgery, you cut back on Calories In by literally constricting the stomach. When Calories In goes down, the right side of the equation should also go down. And since it’s an equation, this means the left side of the equation should go down as well.

So, lower Calories In, and we reduce the amount of fat we store.

Q.E.D, right?

Not so fast.

There is a different way to look at the Energy Balance Equation.

We all assume that changes to calorie balance CAUSE changes in energy balance. But the Energy Balance Equation is simply an equation. To borrow a phrase from science writer Gary Taubes, there is no arrow of causality. Changes in energy balance could easily CAUSE changes in calorie balance.

The alternative theory about why weight gain after bariatric surgery

Some initial problem causes us to store more energy in our bodies. This in turn increases our appetite and decreases the amount of energy we burn off.

If you artificially lower Calories In (by, for instance, banding or shrinking the stomach), your metabolism will ultimately compensate by slowing. Thus, over time, you can expect weight regain. Because until you fix the primary problem with energy storage, you cannot fix obesity, no matter how much you futz with your Calories In and Calories Out.

This second way of looking at the energy balance equation offers us many profound insights into the nature of overweight and disease. Not only does it explain why we see weight gain after bariatric surgery, but it also explains many other paradoxes about obesity.

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