My good friend Alex has extensively written about the topic of fat loss in the past. Some of his best blog posts on the topic are the following:
Resting Metabolic Rate (RMR) signifies the number of calories you're burning at rest, without having to perform any activity. The higher that rate is, the more you can eat without getting fat.
I claim that RMR is very important to fat loss because in people who are overweight or obese, and those who are "permanently" dieting, the RMR can be broken. Also, the concepts of "reverse dieting" and "all-in dieting" have also become very popular in recent years. These terms will be introduced later in this blog post series.
In this blog post, I'll start at the beginning, the introduction of the topic and defining what I'm talking about. The second installment will consider several scientific experiments on this topic, and the third installments teaches you how to improve your metabolic rate.
Ever felt you've gotten fatter on the same amount of food that did not budge the scale previously?
Yes, that really happens...
Say you were doing well on three meals a day for many years. Sure your body weight fluctuated, but on average your weight stayed similar.
You then successfully lost 40 pounds after a 4-month diet. You were on top of the world...
After a week or two of eating around the holidays, however, you regained most of the weight.
All that hard work down the drain...
To make matters worse: the three meals you were eating every day previously are now making you fatter.
How can that be?
You're back at the same weight as before, and yet, the same quantity of food that kept you at a stable body weight for so long now makes you fat?
That scenario every dieter's nightmare, and yet, it happens.
Your "resting metabolic rate" or "basal metabolic rate" went down. Resting metabolic rate signifies the amount of energy you're burning even when you're doing nothing.
So even if you were mostly bed and couch-ridden because you broke a leg, that resting metabolic rate still exists, and you'd still need to eat to support that basal metabolic rate.
Your cells still need oxygen even if you're doing nothing, and the lining of your gut needs to be rebuilt every few days, your heart needs to pump, and your brain needs energy.
Many bodily processes cannot function without a basal metabolic rate. Let me also give a definition of metabolism to further clarify my position:
Metabolism consists of the basic physical and chemical processes in your body to keep you alive. Basal or resting metabolic rate thus refers to the "upkeep" or "foundational" metabolism of your body.
Metabolism is thus essential for living.
If your basic metabolic rate is lowered, then you may burn only 80% or 90% of the energy would ordinarily burn while sitting on that couch.
You may think: "big deal"
Well, your resting metabolic rate matters.
In this blog post I'll tell why that basal metabolic rate matters and lay out how to recover your metabolism.
On the bright side: the loss in basal metabolic rate is not permanent. You can thus regain that lost 10% of calories burned each day...
A lowered basal metabolic rate is problematic precisely because you become more prone to gain fat whenever you eat. Over time, those fat gains make you overweight or even obese.
But why worry about being overweight or obesity in the first place?
Well, both matter as well.
There's no such thing as being healthy and obese. Being obese automatically carries health risks.
Some health consequences of being obese:
And many other conditions...
Shocker (or hopefully not): the obesity problem is getting worse in developed countries.[8; 9; 10]
70% of people in the US are overweight.
30-40% of adults were obese in 2014. Even in children and adolescents, obesity rates are located at a whopping 17%.
What's even crazier is that this data was sourced 5 years ago - the problem is even bigger now.
Obesity rates have been increasing in the last decades, with no end in sight. And the problem is still expected to gets worse over the coming decade(s)...
Where does that trend end?
50% of US adults being obese?
On a worldwide scale, In 2010, 1 billion people were overweight while 300 million people are obese . Many other countries are starting to follow the US' example...
And before you ask, no, obesity is not a genetic problem. Almost no-one is overweight in traditional hunter-gatherer societies.
Whether you look at aboriginals in Australia, the Hadza or Maasai tribes in Africa, the Tukisenta and Kitvans in Papua New Guinea, or the Tarahumara in Mexico, all of these people have healthy body fat percentages.
People in these societies do become obese, however, after transitioning to a Western diet - or better yet: a Western lifestyle. In fact, if you live in a traditional culture and transition to a Western diet you'll have greater risk for obesity than your Western counterparts within a short period of time.[74; 75; 76; 77]
Insane but true...
I'll tell you soon...
Back to developed nations:
Even in developed nations, obesity rates were not as high 100 years ago. So changes in the environment (including food intake) must explain why obesity has skyrocketed.
Genetics do not change in a few generations to be able to explain the obesity problem. Genetics can thus not exclusively explain the obesity problem.
Sure, genetics can load the bullet, but it won't pull the trigger - it's the environment that opens fire...
The goal of this blog post is to explore the concept of "resting metabolic rate" and its relationship to maintaining a healthy body weight.
Let's consider in more detail why "resting metabolic rate" or "basal metabolic rate" matters so much...
The best way to visualize that concept is with a savings account. When you've got more savings in the financial domain, you're more resilient against setbacks.
Car broke down?
No problem if you've got a couple of grand of savings. But if you're living from paycheck to paycheck, car problems can cause serious issues...
With a higher resting metabolic rate, analogously, you're more resilient against setbacks in the health domain. The resting metabolic rate is thus a type of "savings account" for your health, allowing you to burn more calories at rest.
If you burn more calories while doing nothing, overeating on cake or junk food won't set you back (as much). I.e., eating some cheesecake or ice cream will not immediately pack on the pounds.
Sounds great, right?
But the logical follow-up question is: "why do many people have an empty savings account - the metaphor for basal metabolic rate?"
Simple: during starvation, extreme dieting, or if you lose a lot of body fat, your basal metabolic rate can become slower than before. That problem is almost never corrected for in medicine.
So let me tell you about my next steps:
In the next section I'll first analyze the "calories in, calories out" paradigm that's currently adhered to in medicine. That "calories in, calories out" model, while flawed, does help you understand the concept of resting metabolic rate.
Later sections then explore the concept of basal metabolic rate.
It turns out, "calories in, calories" out is not what many people think it is - and it's specifically the concept of basal metabolic rate that undercuts most people's understanding of calories in, calories out.
I'll look at both the flaws and benefits of that model to understand obesity.
Let's first consider what "calories" are.
A calorie is an energy metric. Although I'm oversimplifying, one calorie denotes the amount of energy required to raise one kilogram of water with one degree Celsius in temperature (1.8 degrees Fahrenheit).
In the same way that the energy of foods can be measured, coal or oil also have a caloric value. Simply put, different compounds in your environment can be measured for their ability to raise the temperature of water.
Of course, I'm considering food in this blog post--not fossil fuels. Foods thus also contain energy, which your body may be able to use.
When considering food, the term "Calorie" is often interchangeably used with the term "kilocalories". I'm going to use the term "calories" for "kilocalories", simply because more people use the term that way.
By stating that so and so food contains "100 calories", I thus mean that the food contains 100 kilo-calories.
So let's look at how this model is applied:
"Calories in, calories out" designates the idea that there's a caloric balance in the body. That caloric balance can be grasped in an equation.
The "calories in" part of the equation signifies the calories from food that you take in. "Calories out" indicates the amount of energy that you burn every day, through your basal metabolic rate, exercise, movement, and the cost to process food.
If the "calories in" part of the equation is greater than the "calories out" part of the equation, you'll gain weight--and if calories in is smaller than calories out, you'll lose weight.
Caveat: I'm agnostic towards whether the "calories in, calories out" model is correct or incorrect - I think the model has upsides as well as downsides.
The upside of the model is that the model allows you to get a great grasp of your daily energy intake. One downside is that estimating your true energy needs is almost never correct.
Additionally, you may also have heard from the "eat less and exercise more" principle. That principle is often associated with the "calories in, calories out model". That "eat less and exercise more" principle is also called the "Gluttony and Sloth" theory of obesity.
Eat less and exercise more, implies at a very basic level that many people are overweight simply because they eat too much and exercise too little.
The "calories in, calories out" model is nevertheless completely different from the "eat less, exercise more" principle.
Well, you can adhere to the "calories in, calories out" model without thereby recommending adherence to the "eat less and exercise more" principle.
The reason for that difference is simple:
The number of calories you burn (calories out) can change over time. Your behavior not only influences how many calories you ingest but also the number of calories that you expend.
Through a changing basal metabolic rate, your daily calorie expenditure can change from 1,500 to 1,000 calories per day over time (without you gaining weight or muscle, or moving more).
"Eat less and exercise more" does no justice the occurrence of slowing or increase basal metabolic rate, and is thus faulty in principle.
So let's further explore that "calories in, calories out" equation:
The calorie intake part of the equation is easy to imagine:
The more calorie-rich food you consume, the higher your calorie intake becomes.
So from a calorie perspective, if you eat lots of calorie-rich foods such as pizza and hamburgers, you're more prone to become overweight (and finally obese) than if you're relying on loads of vegetables in your diet.
Only in that specific sense is the "Guttony and Sloth" theory is correct.
Let's break the concept of "calories in" down further:
One gram of carbohydrates supplies you with 4 calories, one gram of fat with 9, and one gram of protein 4 calories. The more protein, carbohydrates, and fat you consume, the higher your daily caloric intake thus becomes.
Don't worry about remembering caloric values.
Taking the bigger picture: vegetables thus contain fewer calories than a steak, simply because vegetables contain very little protein, fat, and carbohydrates.
Remember that the "calories out" part of the equation is not static either: your daily actions influence the number of calories you burn.
No controversy there...
Everybody knows you'll burn more calories if you run a marathon compared to if you're sitting on the couch all day.
The "calories out" part of the equation can change in many more ways than you may think, such eating more protein and increases in small movement even while you're sitting on the couch.[190; 191; 192; 193] Fidgeting or moving your legs more can already influence the "calories out" part of the equation.
Of course, your basal metabolic rate also influences the calories out part...
But if calories out can change on the basis of many variables, then the "Gluttony and Sloth" theory cannot possibly be correct - and "eat less, exercise more" neither.
Quick remark: "calories in, calories out" is not accepted by all modern scientists for explaining obesity:
The "carbohydrate-insulin model of obesity" has been propagated as an alternative to the "calories in, calories out" model.[2; 3; 66]
According to the carbohydrate-insulin model of obesity, carbohydrates specifically make you fat.
While I'm oversimplifying, the gist of the argument is that consuming carbohydrates (through wheat, rice, or coca-cola) raises insulin levels. Proponents of this model then claim that insulin is necessary for energy to be stored as body fat, and that insulin-spiking foods therefore make you fat.
Lowering carbohydrate intake purportedly automatically leads to fat loss, because there's no insulin to shutter energy into fat cells. In other words, replace all carbohydrates by healthy fats, and you'll lose weight automatically.
Although the insulin model of obesity is still heavily being defended today, I'm not using that model in this blog post.[4; 5; 6] To me the "carbohydrate-insulin" model is mostly incorrect, as diets that are high in fat or high in carbohydrates have roughly the same outcome when daily caloric intake is kept equal.
Let's now return to the concept of basal metabolic rate.
Basic metabolic rate generally consists of 70% of the daily calories that you expend. A slowdown of that metabolic rate thus matters.
If your metabolic rate slows down with 10%, you'd burn about 6.67% fewer calories every single day. With a 20% slowdown you'll burn 13.33% fewer daily calories.
Also, notice that a high resting metabolic rate is the easiest way to burn calories: you don't have to exercise to burn that energy off.
During a diet you can have "metabolic slowdown", in which you'll end up with a lower resting basal metabolic rate. In that case, you've lost many pounds, but you may now have a basal metabolic rate that's 10% lower than before.
Let's explore that concept of a metabolic slowdown by using a "Basal Metabolic Rate (BMR) Calculator"
Say you weigh 110 kilograms (242 pounds), are 30 years old, 6 foot tall, and male. With the data points of 1) your weight; 2) age; 3) length; and 4) gender it's possible to calculate your estimated basal metabolic rate.
(Note the word "estimated")
To calculate your basal metabolic rate:
The outcome you get should still be multiplied to correct for your daily activity level:
That multiplier is the same for both genders...
Again, you can only use the Harris-Benedict Formula as an approximation of your daily caloric expenditure. Hopefully you now know why the formula is not fully valid your metabolism can slow down or speed up, making the formula imprecise.
So let's say you decide you need to lose weight (hopefully fat) and cut down.
In that case you'll have to calculate the basal metabolic rate as a 242 pound 6 foot tall 30-year-old male. The outcome of that formula is:
(242*6.23) + (12.7 * 72) - (30 *6.8) + 66 = (1,507) + (914) - 204 + 66 = 2,283 = ~2,300 calories burned through your resting metabolism per day.
After dieting down to 90 kilograms (200 pounds) your resting metabolic rate becomes:
(200*6.23) + (12.7 * 72) - (31 *6.8) + 66 = (1246) + (914) - (204) + 66 = 2,022 calories.
You're now burning almost 300 calories less each day, which equals 4 eggs per day, or 28 eggs per week. Alternatively, you could eat 8 medium pacific oysters to consume those 300 calories, which equals 56 medium oysters per week...
And what if you lost 80 pounds? In that case you'd be able to eat even less.
And these numbers would have to be multiplied with 1.5 if you're engaged in physical labor with light exercise, you'd still expend fewer calories on a daily basis.
In a sense that metabolic slowdown is logical right? You're smaller, carry less weight, and thus burn fewer calories.
The problem, however, is that some people have very low basal metabolic diets after years of dieting. Another problem is that they're still fat - more on that later...
Also, observe from the Harris-Benedict Formula that your basal metabolic rate declines with aging.[67; 68; 69; 70; 71; 72; 73]
One reason for that decline is that teenagers have more "brown" and "beige" fat - fat is metabolically active.[69; 230] Women also have higher levels of brown fat than men.
By exposing yourself habitually to cold, you're able to build up those brown and beige fat deposits. Muscle mass losses are another reason why older people have lower metabolic rates.
Bottom line: your metabolism does slow down with aging, which partially occurs due to having less brown and beige fat and muscle mass.
Your "fat-free mass" also influences your basal metabolic rate. Fat-free mass not only includes your muscles but also your organ tissues, blood vessels, skin, brain, etcetera.
Fat-free mass basically included any tissue in your body that is not fat. During dieting, you'll generally lose fat-free mass.[194; 195; 196]
Contrary to popular belief, it you can gain fat-free mass during your diet, doing so requires lots of resistance exercise.[197; 198; 199; 200] In many cases, however, fat-free mass declines during dieting, thereby lowering your basal metabolic rate.
Fat-free mass is important because without lots of fat-free mass (e.g. muscle) you'll look starved at lower body fat percentages.
(Your body fat percentage is the total amount of fat in your body, divided by your weight.)
If you decide to diet down, you'll thus want to lose mostly body fat while maximizing the amount of fat-free mass you retain.
That's it: you now understand the complexity of the calories in, calories out model.
Section summary: the calories in versus out model describes the energy balance of your body. Both your calorie intake (food) and output (e.g. how many calories you burn at rest) change over time. Your resting metabolic rate makes up the majority of the "calories out" part of the equation, and therefore matters for long-term successful fat loss.
I've laid the groundwork...
In the following installment, you'll learn about metabolic slowdown after near starvation (extreme dieting). Therein I also describe metabolic slowdowns after reversing obesity.
I hope you see what direction I'm going in:
Even from a "calories in, calories out" perspective, the concept of metabolic rate turns the concept of "eat less and exercise more" on its head.
In the next installments of this blog post series, I will do precisely that, looking at some starvation experiments in the past that would now be considered deeply unethical, and drawing conclusions from them about the concept of resting metabolic rate.
After that, the third and last installments considers how you can improve your resting metabolic rate, according to the latest science.
Stay tuned for more!
This is a post by Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - with distinction), and Clinical Health Science (MS), has had training in functional medicine, and is currently a health consultant at Alexfergus.com.
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