In early 2017, an article titled “The Exercise Paradox” was published in Scientific America that made some minor waves. I say "minor" because it’s not something anyone in the fitness industry really wants you to hear about. But it’s something that makes complete sense the more you learn about metabolism.
The article details the research into human energy expenditure. The researchers essentially calculated the amount of energy expended among a present-day hunter-gatherer group and then compared them to sedentary individuals who are much less active. What they found was that there was no difference in energy expended, meaning your friend who runs seven miles a day is likely not burning any more energy than you are doing chores around the house. How the hell is this possible? Basically, your friend is obviously using more physical energy to fuel his exercise, but other aspects that make up total energy expenditure may be down-regulated.
The article ultimately suggests that humans have an energy budget, as does every other animal in the animal kingdom. They make the case that such studies have proven true when comparing animals confined to a zoo and those in the wild. While one is obviously more active, they both expend the same amount of energy. Your energy budget can be used to fuel physical activity or used for body maintenance. And this is likely dependent on a number of factors and slightly altered by age, gender, and physical activity, to name a few. I will stress “slightly."
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Breaking Down Total Energy Expenditure
Someone’s energy expenditure or total daily energy expenditure (TDEE) is made up your resting metabolic rate (RMR), physical activity, and the thermic effect of food (TEF).
Your RMR is basically the amount of energy you burn at rest through the many processes that occur in the body. While the total percentage of energy expenditure can vary, RMR takes up about 60% to 75% of your TDEE. So this will make up the majority of the calories burned from your day. Physical activity is about 15% to 25%, whether that’s exercise or just activities of daily movement.
TEF is the amount of energy it takes to break down or digest food. Obviously breaking down an apple will require more energy than, say, processing a juice drink. This is minor but it can add up. Finally, TEF can encompass about 10% to 15% of your TDEE calories.
Let’s say your TDEE is 2800 calories. This is factoring a normal day in the life you’ve created for yourself. A key point is that this is the sum of a variety of lifestyle choices perpetuated over a series of years. So at this point in time, your body has established a "normal" level. So this may be dialed up or maybe dialed down. The article does reference that norms are 2600 for males and 1900 for females.
If, say, you decide to binge on Netflix and do nothing for a day, you maybe expend or need 2200 calories for that day. So you still have 600 calories left in your daily budget. If you literally just sat on your ass for a day, this extra 600 calories might be allocated for use in your RMR, or if repeated for a few days might cause some weight gain (assuming equal food is consumed).
What happens if you try to outwork your budget to increase your TDEE? So instead of your usual 20% of physical activity calories (560 calories), you go and expend 1200 calories that day. What the researchers are suggesting is that your TDEE will be the same in that you went over your energy budget. How is this possible? By overworking your muscles or requiring more of what your body has allotted for in physical activity, your body will divert energy resources from your RMR to provide you with energy to get through this intense day of physical activity.
This makes sense from an efficiency standpoint. Basically, energy coming in from food is valuable and your body will do with it what's most efficient. If there’s an excess of energy (food) your body will store it as body fat. Conversely, when there’s an excess of required physical activity needed, it will shift its energy needed elsewhere (or use some stored body fat) to supply this output. But it will not use more daily energy if the energy budget has been maxed.
Scrooge is running your metabolism.
You can think of your body’s regulation of energy expenditure as a business and Ebenezer Scrooge is the manager. Scrooge is a cheap S.O.B. He’ll be happy to take in all the money (food calories), but he will be very thrifty in where that money is being allocated. So if old Scrooge gets hit with an unexpected tax bill or property damage, he’d sooner turn out the lights, fire employees, and doc pay than he would just pay it outright. And that’s exactly what your body is doing when you ask it to expend more energy than it has allotted.
While this is saying you can only expend a certain amount of energy a day, it isn’t saying that you’re not capable of doing a lot of unexpected work. In fact, your body is built for these expectations. The whole purpose of this energy is budget is built on efficiency and planning for daily and future events.
Unfortunately, this isn’t the case for energy consumption.
The body is built on feast and famine. So if you consume extra energy, it will prefer to store that away as food. However, while the body does love to hoard food, it really likes maintaining order and homeostasis. In some but not all cases, the body will compensate in a similar manner to an abrupt increase in food energy. If you decide to binge on a random day and eat a whole White Castle Crave Case, the body will be mostly in a state of shock and will divert resources to use and store these resources ASAP. It's sort of like when you receive your tax return: some of that might be tucked away and used when needed, but it’s more than likely going to be spent immediately on bills or luxury items.
What’s the takeaway?
To quote the great Vinnie Tortorich, "Exercise is a horrible way to lose weight" and most definitely a battle you can’t win. A prime design of your body’s metabolism is essentially built to not let this happen. You are, however, designed to move. You just don’t have to get crazy about it. Do some productive activity or go for a relaxing walk and you will likely hit your exercise budget.
Hopefully, people take this information as a blessing, not a curse. I'm not saying that your exercise program is or has been worthless. You still need to actually use this energy budget but don’t look at exercise as this guilt-ridden thing to do to fight off calories. Instead, view exercise (in my opinion weight training) to shape and build the body and relieve stress. If your goal is weight loss, focus on diet.
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Mike Dahlinghaus is an assistant professor of kinesiology at St. Ambrose University. He has a master’s degree in exercise science, a doctorate in health professions education, and is a NSCA Certified Strength and Conditioning Specialist. He can be contacted at email@example.com.