Athletic People have Inefficient Bodies
Conventional wisdom tells us that athletic people have high metabolism while nonathletic people have low metabolism, right? After all, many of us can recount the times in which we ate the same amount of food and perform the same amount of activity as a friend throughout the day, yet you gain more weight than they have because they have a higher “metabolism” than you do. It then seems as if metabolism allows you to burn more calories. If this is the case, then this essentially means that nonathletic people have more efficient bodies, right?
Mathematical Example:
Let’s say that there are two people: you and Joe. You and Joe eat the same amount of food during lunch and hence, you both gain 1500 calories. You and Joe then play basketball together later that day and perform the same amount of work while playing. However, by the end of the day, you gain 0.15 pounds (there are 3500 calories/pound of fat) while Joe gains 0.1 pounds. Typical wisdom would tell you that Joe has a higher metabolism. However, let us look at this situation more closely. Knowing that unburned calories turns into fat, I will safely assume the following simple formula: [Calorie Intake] - [Calories Burn] = [Calorie Turned into Fat], where a higher metabolism will yield a lower [Calorie Turned into Fat]. Now, let’s organize this problem:
You
- [Calorie Intake]: 1500
- [Calorie Turned into Fat]: 500
- [Calorie Burned]: 1000 (1500 - 500)
Joe
- [Calorie Intake]: 1500
- [Calorie Turned into Fat]: 350
- [Calorie Burned]: 1150 (1500 - 350)
Now, because a more efficient body burns less calories per calorie intake, I will define efficiency as [Calories Burned]/[Calorie Intake], where a lower number means more efficiency. Thus, we get
You
- Efficiency: 0.7 (more efficient)
Joe
- Efficiency: 0.8 (less efficient)
From this, we can see that your body is actually more efficient than Joe’s!
Non-Mathematical Analogy
This idea can be seen intuitively. If you and another individual consume the same amount of food and perform the same amount of exercise, yet if you end up gaining more weight, then this means that you are burning less energy than the other person because you have more left over energy that is being stored into fat. Thus, you are burning less energy per given activity.
An analogy to this example is fuel efficiency in automobiles. Let us compare two automobiles: a car (e.g. you) and an SUV (e.g. someone with a higher “metabolism”). Let us assume that they both start off with the same amount of gas in the tank (similar to calorie intake from eating) and they both travel from one city to another (performing an activity like sports). By the end of the trip, the car will have more leftover gasoline in the tank (fat) than the SUV, due to a higher MPG. The amount of gas left over in the tank is analogous to the amount of fat that you have gained. It is clear to see that the car, not the SUV, is more efficient because it consumes less energy to perform the same activity.
Knowing that a higher metabolism leads to a more inefficient body, it would then mean that we would all prefer to have more inefficient bodies because it allows us to burn off more calories and gain less weight.
Posted in Nerd Logic
February 16th, 2008 at 5:11 am
I believe your efficiency calculation is missing a very important factor: work.
In your basketball example, you don’t take into account the work produced. I would assert that you can’t say Joe and I produced the same amount of work. He burned more calories, therefore he has done more work. It could be that extra inch he jumped every time, or the extra force he threw the ball with. Even though the time spent playing basketball may be the same, the amount of work created is not.
Think about 2 people, one running for 15 minutes on a treadmill. Another person walks quickly for 15 minutes on a treadmill. They spent the same amount of time on the treadmill, but the work produced by the person running far outweighs the amount of work produced by the by the person walking quickly.
I believe the argument you want to make (and the one I’ve been making to friends) is calorie conservation. Due to the fact I sit in front of a computer all day and don’t move much, I use less energy and need to consume less energy, allowing me to go an entire day without eating sometimes.
Think about a person who just sleeps all day. They never really move, therefore is conserving energy, so to replenish the used energy, they don’t have to eat/consume as much food.
To put this into perspective of HM (high metabolism) vs LM (low metabolism). HM is worse for the environment and overall energy conservation because you’re sort of forced to use up energy even when you don’t want to, while LM allows you to save up energy.
Typically fuel efficiency is measured in MPG (distance/unit of energy), but I would say that car/engine efficiency is DIFFERENT than fuel efficiency. I would say engine efficiency is measured by work/unit of energy. If the car is heavier, it’ll take it more energy to travel the same distance. If I took the engine for a Honda Civic and put it into an Cadillac Escalade, the fuel efficiency is different, but the engine efficiency is the same.
So maybe what you really want to say is calorie efficiency, at which point I’d agree with your analogies.
June 1st, 2009 at 9:43 pm
If you’re basing your judement off of food intake, out of shape people (fat people) eat more food and waste it by simply gaining more pounds instead of using the energy to do something. In addition, athletic people can endure activities longer and make day to day ife far easier for themselves. (Some people can’t even walk a mile…) Calorie efficiency depends on if you’re including overweight individuals who take in more calories than most people anyway. I strongly disagree with “logic” and I must add that I don’t see your point.
January 11th, 2010 at 7:11 am
This is a silly argument, since you are not comparing the same thing. The analogy is this:
The fat person is a Honda Civic, and the fit person is a Ferrari. To do the same task, getting from A to B, the Civic is far more efficient. But personally, I’d prefer to be in the Ferrari.
March 17th, 2010 at 10:03 am
Your reasoning is correct, but your explaination is flawed. That is part of the reason the other comments don’t understand.
Efficiency of metabolism has nothing to do with being athletic or un-athletic; it is simply of function of matter to energy conversion. People with a more efficient metabolism convert a higher percentage of potential food calories into actual usable calories.
Thus if a sandwich contains a potential 400 calories of energy, a person’s body may only actually convert 75% of that into a form usable by the body. So of the 400 potential calories, 100 get sent through the body as waste and excreted. A person with a more efficient metabolism might convert 85% of the potential calories vs 65% for a less efficient metabolism.
So, in the example of an automobile, a person with an efficient metabolism would be comparable to a higher “Thermal efficiency”
July 17th, 2010 at 4:57 am
After reading everyone’s comment here, I’m still confused. Let me put it this way:
Suppose the bodies of you and Joe are built identically in terms of weight, height, shape, etc.. Suppose both of you run on the treadmill for 30 minutes at the same exact speed, pace, and distance. To borrow Krunk’s word, they both did the same exact amount of “work”.
In this scenario, could the calorie consumption vary between the two?
I would incline to say no. I think the laws of physics would dictate that to do the same amount of “work” (in this scenario), the same amount of energy would have to be consumed.
So the issue here is, as Erik points out, not the efficiency at which the energy is used, but at which the energy is converted from food.
But if this is true, those with high (more efficient) metabolism would convert the same amount of food into a greater amount of energy, and if this energy is not used, it would get stored as body fat. This would mean, those with high metabolism would get fatter! But, as we know, this is not true.
So, I’m still confused.