What Rats and Squirrels can Teach us About Getting Fat

Why we get fatWhy 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.

Image Source

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.

Laboratory Rats
This is not Wade, but another guy who loved his furry creatures. [Image Source]
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. 

Taubes writes:

“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.”

Fat Regulation
Here’s the complex process of fat regulation. Don’t bother trying to understand it. [Image Source]
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.

Taubes writes:

“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. 

bear hibernating
A bear spends an entire summer preparing for this. [Image Source]
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.

Taubes writes:

“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. 

why we get fat
How to make an apple sweeter. Oh how unfortunate. [Image Source]
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.

Taubes writes:

“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!


14 thoughts on “What Rats and Squirrels can Teach us About Getting Fat”

  1. Interesting read. It’s a mental battle, for me anyway, to make the right food decisions. I make a conscious effort to ask myself before eating, if my food selections are to satisfy my palate or serve as nourishment to my body. To answer your question, my last meal consisted of vegetables and chicken.

    Your blogs are always on time, keep up the good work!


    1. Hey Tinna you are right in setting your mind straight whether to satisfy your palate or serve to nourish your body, I must say you just gave me a new lesson in healthy decision making. thank you.


      1. I usually always include a wide variety of fresh and frozen fruit, along with some homemade kombucha tea. It works well for a big energy boost, along with tons of fiber and probiotics.

  2. The time took for you to keep us all on our toes and motivated is amazing man. this is an amazing piece, very educational especially the part where you mention the domestic animals, that made perfect and very much relative sense. my Last meal was two egg sandwiches with mayonnaise, not a very good choice with the mayo. as Tinna mentioned the may pleased my palate while the egg was to get some protein so I am set for a solid time through the day. this will definitely change my ways a bit.

    Thanks Srdjan,

    1. Thanks Kat! It seems like a lot of our food decisions are based on ‘taste’ – which is natural; it’s how we’re wired to work (read this to understand). But there are people out there taking advantage of our own biology and create products to feed our consumerist ways. And it’s important that we at least have an understanding of what we’re putting inside our bodies so, in the end, we can make better decisions.

  3. For lunch, I had a homemade spinach salad with corn, tuna, tomatoes, avocadoes and lemon juice ; fresh ground beef, with eggplant and zucchini, and a homemade dessert with cottage cheese, fruits, nuts, goji berries and cocoa powder.
    So I guess (and I hope) 95% of my meal came from nature and I pretty sure that my cat, the neighbouring herds and the next-door squirrels would have love to take a bite 🙂

    That’s crazy all the stuffs we can find in processed industrial food. In the processed food my parents buy, the most commun “ingredient” is “amidon modifié” : modified starch. At least 90% of french processed food are stuffed with this s***. That’s why I love my homemade meals =D

    Very good post by the way.

    1. Homemade is the way to go Fabien. That sounds like a delicious lunch that I wish I could take a bit out of too lol 🙂

      I was just reading this on Wikipedia:
      “Starches may be modified to increase their stability against excessive heat, acid, shear, time, cooling, or freezing; to change their texture; to decrease or increase their viscosity; to lengthen or shorten gelatinization time; or to increase their visco-stability.”

      All in an effort to make foods cheaper and last longer…

      That’s why it’s so important to know how to read nutrition labels and ingredient lists.

  4. Thank you for all the time and attention you put into the research and story telling of this post. I really enjoyed it.
    I remember when I was on the pill in my 20’s and couldn’t lose that 5 pounds of belly fat – ever – no matter how diligently I stuck to my clean eating and training. I randomly switched brands and suddenly the weight dissipated. Getting off it for good had the best effect. Hormones, obviously!
    In my 30’s, I started to have a similar issue. I noticed that the one questionable food in my diet was greek yogurt. Nothing wrong with it, and it’s a great protein source, but I wasn’t paying attention to where the milk came from to make that yogurt. I suspect the BVH or something similar was affecting me. Dairy in general can be inflammatory, so I eliminated it for a while and immediately got lean again. I go back and forth…
    The goal is to be as mindful as possible about what’s in our food…try to get it from the best sources we can afford – I am glad that so much information is available today than it has ever been, and that we have social networks to share it all.
    It’s not right that our food should be making us sick.
    Sort of off topic, but I can’t wait to see Elysium. I feel like movies like that are the sum of our fears of how bad it could get. The things in our food and how it’s making us sick is just part of it. When I think of how many people I know who have gotten cancer or suffer from chronic inflammation, it’s really scary when you start tracing it back to food. I’m rambling lol.
    Great article, thanks again for sharing.

    1. Thanks for sharing your personal anecdotes Betty – it really adds to the point I’m trying to make. Hormones are king. And we have the ability to control our hormones with our food choices.

      “The goal is to be as mindful as possible about what’s in our food”…

      Exactly. That’s really what it’s all about. Being informed and aware of how food affects the body is a crucial step everyone must take.

      Elysium looks like it will be awesome. Wall-E is another example of how bad things can really get 🙂


  5. Taubes experiment is very interesting. I wonder if the same result would happen if this is done with humans. This brings us back to eating natural food so as not to gain fats, just like animals. Makes sense.

    1. Just like animals, our fat stores are driven by nature. I think we would see some very interesting results if we were to run similar tests on humans. Maybe one day!

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