What Rats and Squirrels can Teach us About Getting Fat
Why do we get fat?
It’s a question that has perplexed the scientific community for decades.
It’s a question many of us think we know the answer to, but really we have no idea. Truth be told, we completely underestimate the complexity behind the process of fat accumulation.
While I’ll save the specifics of why we get fat for another post, I wanted to share a few interesting studies that can provide some solid insight into the true reasons we’re carrying around all that extra weight.
And, more importantly, why we’re struggling to get it off.
Oh, and let me be the first to say that it’s far from what you’d expect.
Let me show you what a few rats and ground squirrels can teach us about the process of getting fat.
Note: the contents in this post were inspired by a chapter titled The Laws of Adiposity in Gary Taubes’ book Why We Get Fat.
Let’s jump back to the 1970s for a second. This was a time when young men enjoyed spending their Friday evenings locked up in a laboratory with a bottle of wine examining the behavior of furry creatures.
One such man was George Wade who was busy studying the relationship between sex hormones, weight, and appetite in female rats.
Sounds like fun.So what exactly did he do?
He did what most of us would think of doing: he removed the rats’s ovaries and monitored their subsequent weight behavior.
So you might be wondering what happened when he did this…
Something interesting: the rats immediately started to eat voraciously and very quickly became obese.
So removing the rat’s ovaries made it overeat and thus gain excessive weight, right? The rat consumed more energy than it expended and so it put on a few pounds, correct?
Well, not so fast.
Wade was a clever fellow and so he decided to do a second experiment. He had time on his hands after all.
For the second experiment, after removing the rat’s ovaries, Wade put them on a very strict post-surgical diet. He essentially didn’t allow them to overeat, even though their lack of ovaries made them really, really hungry.
He only gave them the same amount of food they would have eaten had they got to keep their ovaries.
Cool. So what happened?
Something unexpected: the rats got just as fat, just as quickly.
They became very lazy. Very sedentary. They moved only when it was to get food.
“Removing the ovaries from a rat literally makes its fat tissue absorb calories from circulation and expand with fat. If the animal can eat more to compensate for the calories that are now being stashed away as fat (first experiment), it will. If it can’t (second experiment), then it expends less energy, because it now has fewer calories available to expend.” [source]
The conclusion is this: the animal doesn’t get fat because it overeats. It overeats because it gets fat.
Read that again.
Both the drive to overeat and the urge to remain sedentary are effects of getting and being fatter. As Taubes writes, “they are caused fundamentally be a defect in the regulation of the animal’s fat tissue.”Think about this from a cause and effect perspective.
We have this grand conception that the reason we get fat is because we eat too much or we move too little. We have this belief that our bodies follow a simple energy balance (calories in vs. calories out) model that determines whether we gain weight or not.
What this study is showing you is that the cause and effect are essentially reversed.
We overeat and get lazy because we are fat, not the other way around.
So the question then is: what exactly causes us to become fat in the first place (if overeating and laziness are not the problem, but the result)?
In the case of these rats, the reason they got fat was because by removing its ovaries they are unable to produce estrogen. And estrogen, a female sex hormone, influences an enzyme called lipoprotein lipase (LPL) that is designed to pull fat from the bloodstream into whatever cell happens to express this LPL.
So if the LPL is attached to a fat cell, then it pulls fat from the circulation into the fat cell. If its attached to a muscle cell, it pulls the fat into the muscle cell which the muscle cells uses for fuel.
Unfortunately, for these rats, estrogen suppresses the activity of LPL specifically on fat cells. By getting rid of the estrogen, the fat cells become overwhelmed with LPL which then go on a fat sucking rampage.
This is kind of the same thing that happens to women after menopause.
Here’s what’s interesting, however.
When the rats were later re-acquainted with their long-lost ovaries, their estrogen levels normalized and they lost the urge to overeat, get lazy, and get fat. They started acting like normal rats again.
It should be obvious from this study that it is our hormones that have the greatest effect on our fat stores.
There’s more to it than just what we see on the surface.
If we can figure out what elements in our environment mess with our hormones and if we pay attention to how our fat tissue is regulated, we can get a better understanding of why we get fat. And, more importantly, how we can stop getting fatter.
“We have to conclude, as Wade did for his rats, that those who get fat do so because of the way their fat happens to be regulated and that a conspicuous consequence of this regulation is to cause the eating behavior and the physical inactivity that we so readily assume are the actual causes.” [source]
It’s important to understand something.
There’s a difference between being fat and being obese.
Being fat isn’t necessarily a bad thing. It’s something that is natural – biologically driven. Wild animals are naturally fat. Some will put on fat seasonally to insulate them from the cold winters or to fuel their bodies during long migrations or hibernations. Female animals (like humans) get fat during pregnancy to fuel the baby. Males get fat to give them a weight advantage during fights for females.
But (wild) animals never get obese.
In other words, they don’t suffer adverse health consequences from their fat. Anytime animals put on significant fat, that fat is always there for a good reason. Their fat serves a purpose and fluctuates as nature demands.A good example, as Taubes points out, of how carefully animals regulate their fat accumulation are squirrels.
Ground squirrels double their weight and body fat in only a few weeks before summer.
If you were to open them up at their peak weight, oil would shoot up in your face. Gross, but that’s how fat these little guys get.
But the interesting part about this is that there’s very little anyone (read: any scientist) could do to keep this animal from gaining and losing fat on schedule. They will accumulate fat before summer regardless of how much they eat (just like Wade’s ovary-suppressed rats) and they will burn the fat through the winter whether they remain in a food-abundant laboratory or go into full, natural hibernation mode.
It’s really all about survival.
“The amount of fat on these rodents at any particular time of the year is regulated entirely by biological factors, not by the food supply itself or the amount of energy required to get that food.” [source]
So where does this leave us?
What can we learn from these animals and their complex abilities to regulate fat?
Why are humans so different? Or are they? Why are we the only species that has to suffer adverse health consequences because of our fat?
Here’s what’s important to understand:
The human body is very complex. Everything in our bodies (like in an animal’s body) is very strictly regulated and fat tissue is no exception. When a person accumulates excess fat (more than nature has intended), it’s a clear sign that something is changing the way their fat tissue is being regulated. Read: something is really, really wrong!
But, if everything is driven by nature, why do we get so fat that we suffer health consequences while animals don’t?
It’s because we have the ability to make a choice as to what we eat and how we live.
And, unfortunately, we live in a society that makes it very, very difficult to make good choices (or even have an understanding of what a good choice is). We live in a world where one can profit from another’s poor health.The reason we suffer from our fat is because we choose to consume foods that are, by nature, not intended for human consumption. Foods that are super-normally stimulating, addictive, and lack any valuable nutrients.
Foods that are, coincidentally enough, cheap to make and easy to sell.
Foods that are made in a laboratory, not in nature.
And it is the consumption of these foods that is messing with our hormones which, in turn, regulate our fat storage and accumulation.
Poor food choices are at the root of our fatness.
“Obesity does not come about because gluttony and sloth make it so; only a change in the regulation of the fat tissue makes a lean animal obese.” [source]
Animals don’t have to worry about that kind of stuff in the wild. But it doesn’t mean that they can’t suffer from poor food consumption. Their bodies regulate fat very similarly to humans.
Is it a coincidence that domesticated pets (who live by the choices made by their human owners) are beginning to suffer from the same kind of health issues as humans are? Certain studies from various parts of the world have estimated that between 22 and 44 per cent of dogs are overweight or obese, and these figures are similar for cats.
I hope it’s starting to make more sense now.
You have to take control of your own health and your own choices if you want to have any chance of fighting the fatness.
I hope this post has opened your eyes and provided you with a little bit more insight into why, as a society, we’re lugging around extra weight and struggling to get it off.
Now I want you to do something for me and yourself:
Think about the last meal you had. What was it? Where did it come from. Was it food that came from nature? From a laboratory? Would an animal eat it in the wild?
Leave your responses to these questions in the comment section below. I’d love to read them.
And, if you think this post can be of value to others, please do me a favor and share it with your social circles!