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5 Metabolism Myths Debunked
Find out how metabolism affects the way your jeans fit, how your genes may or may not affect your metabolism—and whether eating hot peppers will help you lose weight.
Everyone knows someone with a crazy fast metabolism: the girl who eats junk food and doesn’t gain a pound, or the guy who drinks as many beers as he wants without growing a beer belly.
Are these people superhuman, endowed with metabolisms faster than a speeding bullet and more powerful than a bacon cheeseburger? Did they get lucky in the genetic lottery? Or are they secretly going to the gym when no one’s looking?
It’s probably a combination of all three, though “superhuman” may be stretching it. Metabolism, that mysterious process of energy production, is often the reason—and the excuse—many people rely on for understanding why bodies are big or small, fat or lean. But what is metabolism, really?
Increased muscles and muscle density will lead to the body burning more calories, which in turn will raise the body’s basal metabolic rate.
Metabolism is commonly understood to be the rate at which the body burns calories. This is only half true. Metabolism is the process by which the body breaks down food and converts that food to energy. Those two steps—the breaking down and the rebuilding—are processes called anabolism, or constructive metabolism, and catabolism, or destructive metabolism. In anabolism, small molecules are changed into larger, more complex molecules of carbohydrates, proteins, and fats (the holy trinity of nutrition). Anabolism requires the input of energy, in the form of food calories, and is the process by which the body stores energy. In catabolism, cells break down those large molecules to release energy and dispose of waste. This energy release provides fuel for anabolism. In this way, anabolism and catabolism exist in balance with each other and are the ying and the yang of metabolism.
So what about burning calories? Seriously, how does she eat French fries and stay so thin? It depends a lot on what else she’s eating, and how much exercise she gets. The golden rule of metabolism is that if energy consumption (calories) and energy production are equal, overall weight will stay the same. Weight loss occurs when the amount of energy the body expends is greater than the amount of energy the body consumes. If the body consumes more calories than it burns, those calories are converted into energy and stored as fat. Seems pretty simple. And it is, so long as fad diet mumbo-jumbo and metabolism-boosting supplements aren’t in the way.
Here are five metabolism myths, debunked with help from Marc Plano, functional diagnostic nutritionist, holistic health counselor, and founder of The Plano Program:
Myth 1: Metabolism is genetic and can’t be changed. False. Well, partly false. All humans (and actually all living things) are born with the ability to break down food in order to create energy. In this sense, metabolism is genetic. “Metabolism is as unique as a fingerprint, some people metabolize food very fast and others very slow,” says Plano. Whether metabolism is “fast” or “slow” is determined by metabolic rate, called basal metabolic rate or BMR, which is the amount of calories one burns while at rest. Even at rest the body is active—organs are working, cells are growing and dying, digestion is occurring—and energy is being used for these processes. Someone with a low BMR will burn fewer calories while at rest, while someone with a high BMR will burn more calories while at rest.
What’s burning the calories while the body is resting? Muscle and fat, though not equally. For every pound of muscle the body burns 35 calories a day, while for every pound of fat burns just two calories per day. Increased muscles and muscle density will lead to the body burning more calories, which in turn will raise the body’s BMR. So weight training is a surefire way to raise BMR. But aerobic activity, too, will help the body to burn calories, not only from the immediate activity but also from the calories that will be used later, while the body is resting. All this work will ultimately increase BMR. So even if slow metabolism is in your genes, you don’t have to live with it.
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In the following conversation an assumption is made. I assume the importance of the article is metabolisms relevance to weight management and/or weight loss. This conversation is made in that light.
Crazy metabolism? Not quite sure what that means. For all humans, resting tissue metabolism is essentially the same per cubic inch of fat and/or muscle tissue. There is nothing crazy about it. It's quite straightforward and simple, in the end.
How do our genetics come into play? Our genetics determine the number of fat and/or muscles cells. Notice the distinction between determination of cell number vs. metabolic rate. This is an important distinction.
What can we meaningfully control? We can control our activity, work and exercise behaviors. With respect to metabolism this is the only conversation of merit.
Let's go through each of the myths presented here. But before we move into that I make this suggestion. Get an understanding of Pareto's Law (aka the 80-20 rule). A simple Google search will suffice. Ultimately what this law says is that we should pay attention only to what matters.
Not to change the subject, much, but are you familiar with Jewel? Only kindness matters in the end.
Okay, here we go.
Myth 1: Metabolism is genetic and can't be changed.
In simple terms, your metabolism is the way your body burns up all of the calories from the food you eat. Metabolism has three components commonly examined - resting metabolism, metabolism from digestion and metabolism from physical activity. All of these considered together are referred to as total daily energy expenditure (TDEE).
Resting metabolism is not of interest in weight management conversations because, well, it's resting. Resting metabolism doesn't help us burn any meaningful excess calories that might help us loose weight and/or burn off excess fat.
There is a common conversation that we can increase muscle tissue, through exercise and activity, and with increased muscle mass have a higher resting metabolism. As exciting as this initially sounds, it's not what is of merit. What's of merit is the thousands of calories burned in activity to gain and maintain even one pound of muscle. This article states that one pound of muscle burns 35 calories per day. But if you stop exercising that pound of muscle will fall away within a very short period. It's the activity and exercise to maintain the pound of muscle that is of merit! Over a life time one will burn many, many thousands of calories to maintain the one pound of muscle. Now THAT is exciting!! Burn the thousands I say. Don't give the 35 a moments thought.
Digestive metabolism isn't of much interest either. For most people it's about 10% of their entire metabolism. But for no person on a reasonable and healthy diet is it ever greater than the amount of food digested across the intestinal wall and into the blood stream. It becomes a moot point. All we care about is the amount of calories that get into the blood stream. It's those calories that cross into the blood stream that might end up in a fat cell. Don't eat them to begin with is the ultimate point. Trying to increase your metabolism by eating of anything makes no sense whatsoever.
Myth 2: Metabolism is the same for men and for women.
This is a fuzzy conversation. But an educated response would likely be "so what". There is no relative difference between male and female muscle cells or fat cells. On a cell to cell comparison they are the same. What is different? On an absolute scale, on average males have more muscle cells and females have more fat cells.. But this is like the proverbial comparison of apples to oranges. It does no good for the 140lb female to compare herself to the 350lb muscle bound football player. For all practical purposes they are entirely different critters. Comparing them simply and only confuses the conversation. Each person, female or male, is traveling his/her own unique metabolic path.
To make this more clear, it really doesn't matter if we compare from one male to the next either. I can not compare Lance Armstrong to myself. Lance is about 175lbs compared to my 230lbs. In a layperson conversation, there is no practical way to physically compare us. Additionally, there is no behavioral way to compare us either. Lance is a cyclist where my activities are volleyball, outrigger canoes and weightlifting. There are to many variables. We can not be compared to each other in a way that is meaningful or helpful.
What does matter? What is meaningful? Your own personal activity and or exercise behavior.
Myth 3: Hot peppers and green tea will speed up your metabolism.
This actually is true. But the point ends up being irrelevant. All food increases your metabolism. Digestion of food contributes to an increase in that component of metabolism referred to as the thermal effect of food (TEF). When considering metabolic contribution to weight management, it's not meaningful or useful to consider energy expended in digestion. In a reasonable and healthy diet, whatever the metabolic increase is from any given food type will never offset the caloric intake into the body. It does not matter if we discuss carbohydrates, protein or fat. The amount of calories that cross the intestines into the blood stream (digestion) will always exceed the calories burned in the process of digestion. To the point, protein (better stated as amino acids) does not contribute meaningfully to metabolism for weight loss or weight management.
The only meaningful conversation to be had is a decrease in portion size and a redistribution of those calories throughout the day. I assume the point of decreased portion size is relatively obvious - decreased calorie intake. But what is meant by redistribution of calories throughout the day? It's found that people that eat many meals throughout the day end up eating smaller portions and taking in significantly less calories.
Notice this has nothing to do with affecting metabolism in anyway. A common myth is that eating many times per day is advantageous due to an increased metabolism. This is not true in any meaningful way. Take, for example, an apple. If we quarter the apple and eat a quarter of it every three hours does this increase the TEF for that apple? No. It takes the same amount of metabolism to digest the apple in either case - all at once or in four different sittings. We could make an analogy. TEF (digestive metabolism) is a measure of how much energy it takes to do a certain amount of work - digest the apple. We could compare this to driving a car around town. In town we are going to have stop and go traffic and average maybe 25 miles per hour. It does not meaningfully matter if we drive for 15 minutes and park for a couple hours, and then drive another 15 minutes and park for a couple more hours and so forth until we drive for an hour or if we just drive around for an hour without parking. We still burn the same amount of gas. It's the same for digestion of the apple. Do the work of digestion all at one time or in quarters, the metabolic work to do that is the same in both cases.
Myth 4: Eating one big meal per day will boost your metabolism.
This idea was just addressed above. To further clarify, the value of eating several meals throughout the day has to do with maintaining blood glucose (sugar) throughout the day. The nervous system operates optimally off of sugar. In the end, it really only functions well on sugar. If we maintain appropriate blood sugar levels, whether diabetic or not, the brain stays satiated and the hunger drive is suppressed. Because the hunger drive is suppressed, the general tendancy is to eat less calories per day.
In the end, people that habitually eat one meal per day end up eating significantly excessive calories and gain weight. The recommendation is to eat small meals throughout the day.
Myth 5: Everything eaten after 7:00 p.m. turns to fat.
It's not relevant what time you eat a calorie. What's relevant is calories in vs. calories out. End of story.
That said, there are a couple issues to consider with the clock. Eating close to bed time does not allow sufficient time for digestion to occur. This ends up being an anatomical issue. If we go to bed and lay down with a full stomach there is a strong chance that food will travel up into the esophagus. Stomach acid will accompany the food and begin to damage the lining of the esophagus. So, we don't want to eat to close to bed time and we certainly do not want a full stomach.
However, we don't want to go to bed hungry either. As stated in the article, this leads to late night over eating.
Terry Martin
ACSM - Health Fitness Instructor
Thank you.
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