Weight Loss/ Wellness

The Weight of Exercise

What I got wrong and what I learned

Those who know my work here on Medium are aware that I write a lot about nutrition, metabolism and weight loss. I also frequently comment on stories on those topics posted here by other writers. In those comments, I often point to errors made either by the author or by the researchers that the author references in their story. Well, in this article I correct an error I’ve made in my articles and comments over the past two years.

That error deals with the role of exercise in weight loss.

There is ample research that shows one aspect of the Energy Balance Model (EBM) of weight loss is correct. As background, the EBM posits that the body looks to balance the amount of energy coming in with the amount going out. When used as the basis of a weight-loss strategy, it has a bad track record. It is the EBM that spawned to “eat less/move more” (and its cousin, Calories In/Calories Out) approach that anyone looking to lose weight has been told to follow — and when they do, it fails, like it always does, their weight-loss coach, nutritionist, dietitian, or doctor blames them for not complying 100% of the time. Using the basic idea of the EBM, weight-loss coaches assume that if you eat less, or exercise more (or both), you will create an energy deficit, and your body will make up the difference by using your body fat for the missing calories.

While it is true that your body will experience an energy deficit, it will only pull energy from stored body fat for a short time; then it will defend this deficit — because your energy management system doesn’t understand “wanting to lose weight.” After a while, your body will do some things that result in a weight-loss stall, and then gaining weight — even while you are eating less and exercising more.

This article explains what and why this happens in more detail:

I had always commented that while exercise is great for your health and feeling of well-being, it was a poor strategy for weight loss. The reason stemmed from research that shows the body will expend less energy during the day to compensate for your extra exercise. So, if you expend 600 calories at the gym, your body looks to take it easy the rest of the day. You might feel like taking the elevator instead of the stairs, or spending the evening on the couch because you just don’t feel like doing anything in the evening. This relates back to the part of the EBM that holds true: If you overspend at one point, your body looks to save later.

There is, however, a way that exercise can help with weight loss, and loss of body fat specifically — and it’s not related to calories. Here’s how it works.

Insulin controls the transport of glucose to cells in the body. As you eat carbohydrates and, to a lesser extent, protein, the level of glucose in your blood rises. In response, your pancreas secretes insulin to manage that glucose. Over time, for many of us, our cells get resistant to the actions of insulin, so it takes more and more insulin to manage even a typical level of glucose. A high level of insulin, however, also blocks the process of using body fat for energy. So while the insulin level in your blood is high, you can’t use body fat for fuel. The more resistant your cells are to insulin, the more insulin you need your pancreas to secrete into your blood and the longer you have to wait to use fat for energy — as it takes time for the insulin to get filtered out of your blood when it’s done managing your glucose. This is why you get hungry (or even hangry)between meals. Even if you are overweight, your body can’t use your body fat, so it motivates you to eat more.

This process of becoming insulin resistant, and needing more and more insulin to manage the glucose in your blood occurs day-by-day, year-by-year, decade-by-decade. Maybe you notice you are gaining two pounds a year — then 30 years later, you are 60 pounds overweight. And the advice your doctor has been giving you (eat less/move more) is just making it worse.

Muscles to the rescue!

The one way exercise can help relates to how muscles take up glucose. Like our other cells, insulin can open up the muscle cells to let some glucose in. But, if you have developed insulin resistance, it’s taking more and more insulin to do the job and contributing to the problem.

But muscle cells can take up glucose without the help of insulin when you are exercising. Specifically, when your muscles contract, they can take glucose right out of your blood. The key to weight loss, when it comes to exercise, is when you do it because that can influence how much insulin your pancreas needs to secrete. If you exercise 15 to 20 minutes after a meal, you can let your muscles take up a lot of the glucose that was in the carbs you ate at that meal before your pancreas gets around to producing all the insulin it would normally need to in order to manage that glucose. This exercise will help your cells become more sensitive to insulin over time.

I know, you are thinking who wants to work out 15 minutes after a meal?! The good news is that even walking helps with respect to ridding the blood of glucose. The glutes and leg muscles are the biggest in the body. So, going for a walk after a meal can greatly reduce the amount of glucose your pancreas needs to deal with. This won’t be a quick-response weight-loss strategy. But little by little, it will help. And you don’t need to get in 10,000 steps after the meal. Just do whatever you have time for and/or enjoy. Make it something you look forward to, and it won’t seem like a chore.

Thank you for reading this article — hopefully, it contained something you found useful.

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