Why You Can’t Outrun Your Fork and What To Do About It
You can’t outrun your fork, sorta speak, because your body’s metabolism adjusts to exercise. As a matter of fact, it does that with calories too. Learn why, and what to do about it.
THERE’S THIS thing called “Homeostasis” and although it may seem unfamiliar, you have experienced it throughout your life. Homeostasis is the regulation and maintenance of our body’s internal environment within certain narrow ranges that support life, irrespective of changes in our external environment.
Take temperature and donuts for example. You may be walking through a snowstorm, but your body will do its utmost to keep your body at 96.8 degrees. Or when you eat that donut causing your blood sugar to spike, your pancreas will detect this imbalance and secrete insulin to cause liver cells to “take up” this sugar in the blood. That sugar in that donut is acidic which may cause your blood pH to become too acidic, and thus your lungs and liver will act to bring down this acidosis in order to get pH down to the ideal acid/alkaline level of 7.40.
Adjusting to cold weather and sugar are examples of homeostasis in action. Without this mechanism, you would freeze, become diabetic and get sick much faster.
Unhappily, this is also true with exercise and calories because of this thing called “Metabolism”. Metabolism is the mechanism of homeostasis that you have experienced every time your exercise or diet regimen has stalled and is no longer making you stronger, fitter or leaner.
In this article, you’ll discover:
- Why you can’t outrun your fork
- How homeostasis drives metabolic adaptation
- How to mix up diet and exercise to keep getting favorable results
In a Forbes article by Nancy Fink Huehnergarth entitled Why You Can’t Exercise Your Way To Weight Loss, anthropologist Herman Pontzer explains that our bodies adapt to physical stress, like exercise, such that exercising more vigorously does not necessarily result in more calories burned. He conducted a study of 300 men and women and found that people with moderate activity levels expended only 200 more calories per day than those with sedentary lifestyles, and that the most physically active people expended the same amount of calories each day as people who were only moderately active. (1)
Now, before you couch potatoes leap up and high five each other, please understand that although Dr. Ponzer’s research offers an explanation why so many people who initiate an exercise program alone lose little or no weight, it does not mitigate the other critical benefits of regular exercise, such as the decreased risk of cardiovascular disease (the number one cause of death in the U.S.), depression and type 2 diabetes (now considered a health epidemic in the U.S.).
“Exercise is really important for your health, said Dr. Pontzer. “That’s the first thing I mention to anyone asking about the implications of this work for exercise. There is tons of evidence that exercise is important for keeping our bodies and minds healthy, and this work does nothing to change that message.” (2)
Inevitably, some people who read this will think of a few people they know that eat ravenously, but by virtue of their exercise, stay thin as a rail. For me, ultramarathoner Dean Karnazes comes to mind.Dean Karnazes
Mr. Karnazes is basically inhuman. His extreme athletic endeavors include running 50 consecutive marathons, one each day, finishing with the New York City Marathon in three hours flat. Dean has been known to have multiple pizzas delivered to him at set points along his long runs. He folds them up and chows down, and yet he stays very lean.
Dean is an outlier, and as such Dr. Pontzer’s study, and the others I’m about to share with you, are not relevant to him. And if you do, or intend to, exercise like Dean, I suggest you go find yourself a good massage therapist and dispense with reading the rest of this article.
For the rest of you, realize that Dr. Pontzer’s conclusions are not unique to his research; consider these six collected by Ms. Huehnergarth: (1)
- A 2007 study monitored 200 sedentary, overweight/obese adults for a year during in which they increased their physical activity level to five to six hours each week, but made no changes to their diet. At year’s end, the men had lost an average of only 3.5 pounds, the women only 2.5 pounds.
- A 2009 meta-analysis (when researchers review and analyze a group of studies) of 18 studies involving more than 18,000 children found that Body Mass Index (BMI – a weight-to-height ratio used as an indicator of obesity) did not improve with school-based physical activity interventions.
- A 2011 meta-analysis found no association between physical activity levels and fat mass in children, concluding that physical activity is not likely the “key determinant of unhealthy weight gain in children.”
- A 2012 meta-analysis of eight studies that investigated diet-only, exercise-only and diet and/or exercise weight loss programs, found that the exercise-only programs were the least effective.
- A 2013 study found that between 2001 and 2011, physical activity levels had increased in more than two-thirds of U.S. counties, and yet this did not prevent an increase in obesity in almost all counties during the same time period.
- A 2013 review and commentary presented evidence that physical activity levels are similar “between societies with low versus high obesity prevalence,” concluding: “Only [a] reduction in calorie intake will result in weight loss, whether done in isolation or together with increases in exercise.”
As an avid exerciser, I admit that these findings mess with my sensibilities, but unless you’re an outlier like Dean Karnazes, it makes sense to consider the evidence. In this case, the evidence supports what we might have guessed if we kept our understanding of homeostasis and metabolic adaptation in view – the body will try to adjust to new inputs such that it maintains its established norms.
A Brief Primer On Metabolic Adaptation
Let’s dig into this metabolic adaptation relative to weight loss, and for this I’m going to refer to an article called What You Need To Know About Metabolic Adaptation written by Eric Trexler, a strength coach and power lifter.
Mr. Trexler points out that when there’s a caloric deficit (more caloric energy is expended than consumed), you lose body weight (hopefully fat rather than muscle, which you can help ensure by ingesting adequate protein and doing resistance exercises.) This means that the body’s energy supply is low, and the body responds by adapting to it in three possible ways by:
- Increased mitochondrial efficiency (less calories burned to produce the same amount of ATP, a coenzyme that transports chemical energy within cells for metabolism)
- Decreased energy expenditure (metabolic rate)
- Elevations in hormones that promote catabolism and hunger, with decreased hormones that promote anabolism, energy expenditure, and satiety
These three responses are the body’s homeostatic response to caloric deficit through the mechanisms of the mitochondria (the cell’s “energy powerhouse”), metabolism and hormones.
The result is that weight loss slows down or stops.
At this point, the insightful of you may blurt,
“Hey Joedude, isn’t this homeostasis thing messing with a favorable metabolic response both to exercise and a reduction in calories?”
Ah, insightful, grasshopper. Yes, it does. So let’s explore a solution.
What To Do About Metabolic Adaptation To Exercise and Diet
You can’t outrun your fork, as they say, but perhaps we can tune the fork and the run.
Say you begin a diet, start exercising or both. If effective, your diet will ensure that you’re consuming fewer calories than you’re expending, and your exercise will amplify the caloric expenditure. All is well for a bit, but, eventually, the dreaded metabolic adaptations occur which winds up slowing or stopping your weight loss, whether from diet and/or exercise.
What do you do?
You mix it up!
Mixing things up confuses homeostatic mechanisms. If you were to consistently lift 30 pounds above your head and it was initially hard to do, your muscles would respond by getting stronger and larger. At some point, however, 30 pounds would no longer be challenging and your strength and muscularity would plateau.
One or all of those three adaptations listed above would happen, and what you would need to do to disrupt such adaptations is to disrupt what you’re consistently doing – lifting that 30 pounds, or whatever. Maybe you’d start lifting 40 pounds above your head, or lifting it at different angles, cadences, repetitions, the number of sets, time between sets, etc.
Given that lifting a weight above your head does not constitute a balanced exercise program, let’s apply this “mix it up” strategy to what you might actually do for exercise.
I like what Andrew Read over at BreakingMuscle.com has to say about training variables. He lists four you need to consider as pertain to resistance training (calisthenics or weight lifting):
- Exercise Selection refers which exercises you’re doing
- Volume is how many sets and reps of a given exercise you do, as well how many times per week you do it (also called frequency)
- Intensity is how heavy you are training in comparison to what would be your absolute potential in that lift (often called a 1RM, or the load you could lift once and once only).
- Density is how fast you can lift your given volume in a workout – 100 reps done at a given load in thirty minutes is a less dense workout than the same reps and weight done in 28 minutes.
You would mix this up by choosing an exercise program with a defined selection of these four variables and stick with it for a month or so, and then change things up for the next month, etc.
Perhaps cardiovascular conditioning is more your thing than resistance training. Consider mixing up your exercise program as follows, doing each on separate days or in combination if well tolerated, and focusing on a consistent set of exercises for a month or more before mixing it up for the next month, etc.:
- Slow, long run
- Sets of slow 400 meter jogging interspersed with 100-meter sprints
- Sprinting hills and stairs
- Long bike rides peppered with hills
- Bike sprints
- High Intensity Interval Training, such as those discussed here.
- Burpees (get some upper body work in there)
Likewise, you would take a diet based on consistent caloric deficits, and shake it up. Among the things you could do with a diet is:
- Consume fewer calories than the baseline one or two days per week
- Consume more calories than the baseline one or two days per week
- Fast or just drink vegetable juice for one day per week
- Do some Intermittent Fasting on certain days
What you need to remember is that your body wants to conserve energy. For most of our evolution, we weren’t awash in convenient food and lounge chairs, but rather experienced sustained periods of fasting and constant moving about to find food. There would be no human beings if our bodies were not able to conserve energy during such lean times.
Fast-forward a few thousand years. Now two-thirds of us are overweight and don’t move much. Our bodies have adjusted to this, and will adjust to any changes in that status unless you regularly mix it up.
Any questions or comments?
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