Why We Get Fat ... Lessons from Obese Humans & Cafeteria Rats

Vacation bump!  Original Post Date:  3/9/11

One of the more interesting things (to me) to come out of the "cafeteria rat study" is what the composition of the diet eventually chosen by the rats came out to be.  I'm just going to focus on the SC (standard chow) and CAF (SC + human snack foods) diets in this post.

To recap, the SC had a composition F/C/P of 10/64/26.  When offered this chow along with a rotating selection of three human snack foods from the following list, the rats only ate 15% of their diet as chow (the wording of this is unclear, but their total consumption is ultimately what's important).  The composition of the diet they ended up eating?  CAF was F/C/P of 44/46/10  (note: I've detected slight discrepancies in the numbers here that involve a 1-2% swing in either direction) .  One might think the rodies were only offered fatty snacks, but this is not the case as can be seen in the table below:
 {click to see full size}

The rats likely ate more from about half-way down the list on down in order to get to over 40% fat in their diets.  

We often hear that NHANES tells us Americans are consuming less fat these days (as a percent on average that is true to a nominal extent, but on an absolute basis we consume more) and the majority of the 300 some-odd additional calories we're consuming are carbohydrates.   From this, we are to conclude that it's the "low fat dogma" of replacing fats with carbs that has made us fat.  Somehow us Americans are really taking to heart all of this healthy whole grain, eat what the guvmint tells us to (aka food pyramid) stuff.  

But I think such studies and approximations are somewhat flawed as they are averaged out.  As we can see from the CAF rats v. the SC rats, when exposed to these obesogenic foods, some rats only got a little bigger than the controls - but some got significantly more obese - a few weighed about twice the mass of their counterparts by study end.   

So the 35% reported average increase in consumption masks somewhat the fact that some rats barely ate more while others were eating perhaps even double the amount of others.  When I hear stats like Americans averaging like 80g/day sugar intake I am flabbergasted.  I don't know anyone in my life that eats that much sugar daily, even my husband when he ate more sweets.  (Yes, I'm aware of hidden sugars).  This tells me that we have folks like the former Jimmy Moore who are consuming a ton of sugar and throwing the average. I don't think looking at average consumption for populations provides us with much useful information to determine the cause of rising obesity rates.  Because there are still a ton of skinny folks running around in my circles.   

It is more instructive, IMO, to look at what exactly it is that obese people eat.   To wit we have a study from the LC weight loss realm that monitored the intake of  10 obese subjects (3 men/7 women) in a hospital setting.  For two weeks participants were instructed to consume their "usual diet":
"The clinical research center kitchen provided all food and beverages, and we weighed and recorded everything that was consumed. The food was prepared in the hospital kitchen, as well as in the clinical research center kitchen, and also included foods from local fast food establishments. Participants selected from standard hospital menus each day during their usual diet; participants were also encouraged to request food from the “outside.”  To supplement the hospital menus, we used brand-name foods or fat foods for which nutrient data were available (for example, McDonald’s sandwiches, donuts from Dunkin’ Donuts, and Oreo cookies)."
The intake data from this study is, thus, far superior to dietary recall and self-reported intake.  And, of course, it is ACTUAL intake of obese people, not averaged intake for a population.  Using the means, the Human CAF diet consisted of 3170 calories - 309g carb, 154g fat and 137g protein.  This works out to 44% fat / 39% carb / 17% protein.  

So lower carb than many reducing diets by percentage "by a mile".  The 154g fat on average amounts to 1386 cals - a.k.a. about maintenance or a smidgeon deficit level intake for this post-menopausal woman who has put her metabolism through way too many diet "hoops".   Also a bit higher protein than the CAF rats but otherwise comparable.  

So, when we choose to eat high calorie (usually high fat), low nutrient food, we get fat.  DUH!


Mirrorball said…
I want to blow my brains out every time someone says that low-fat dietary advice has made us fat. The only time in my life I followed such advice I LOST weight, though it made me crave high-fat foods. I got fat by eating the CAF diet, with lots of sugar and trans fat, and got thin by switching to home-cooked whole (Paleo) foods.
CarbSane said…
I'm not totally paleo, but the chicken soup I've got simmering on the stove could win a challenge on Top Chef it is THAT good. Bone broth, chicken, carrots, celery, onions, mushrooms, wild rice, spices and a bit of salt. YUM

I accidentally picked a low fat canned soup off the shelf to have last fall while traveling. Ugggggh. But mine probably has not a whole lot more fat ... just a whole lot more flavor and nutrition!
It's not just the trans fat in the SAD diet that are a problem, it's also the excess omega 6s from all the veggie oils in processed foods.

I've seen recommendations to keep total PUFA to under 4% of daily calories. Good luck doing that when the lion's share of the fat in an industrial diet comes from corn oil or soy oil or whatever that are 50% PUFA or higher!

I find Peter@Hyperlipids view of fructose from excess sugar, omega 6s from excess veggie oils, and refined grains all work to damage the liver, leading to hyperinsulinemia compelling: http://high-fat-nutrition.blogspot.com/2010/03/getting-fat-is-good-official.html
CarbSane said…
Hi Beth, I haven't seen much support for Peter's graphics in that post. That hinges on liver damage causing the liver to pump out glucose that stimulates the pancreas to pump out insulin and then we get fat.

Looking at my previous post on the CAF rats, the sugar rats (35% sucrose diet) had damaged livers, but in a different way, but had less damaged fat tissue. They didn't overeat any more (surprisingly to me) than the HF rats. Their fat didn't get as sick, their NEFA was lower, and their glucose tolerance was better.

Unger & Scherer are more on target, except rather than using the judgmental terms of gluttony and sloth I would use chronic energy excess. This is where just about every study leads. However once we exceed the protective threshold of our fat cell capacity, it appears the fat tissue IS the cause of a lot of problems.

I think "the ability to get fat" can be good, but getting *too* fat is never good.
Anonymous said…
The laws of thermodynamics CAN and DO get VIOLATED.

They are NOT good enough to explain our observations anymore. The QUANTUM THEORY is where we need to move on to . Conventional physics laws are NOT good enough anymore to explain what we have seen in the last 5 years or so.

The Big Bang itself VIOLATES th First Law of Thermodynamics.

BLACK HOLES violate thermodynamics as we as Einstein's theories.

The laws of thermodynamics completely FALL APART AND BREAKDOWN as we approach the Event Horizon of a black hole.

Einstein's theories are USELESS as we enter the singularity0 the very center fo a black hole.

Laws of science CAN be DISPROVED or MODIFIED when new evidence contradicts them.

The laws of thermodynamics ARE BREAKABLE and i GAVE YOU EXAMPLES.

The textbooks are being RE WRITTEN Look up DR MICHIO KAKU.
CarbSane said…
Can you please quit SHOUTING? I'm going to spontaneously combust otherwise.
RRX said…

What exactly have we seen in the last 5 years that makes thermodynamics violated in our EVERYDAY WORLD? The last time I checked, quantum theory is not necessary on the level of our daily lives. Thermodynamics and conventional physics are still the best theories to use and explain the world of our daily lives. Have you ever actually discussed this opinion of yours with an actual physicist? Any physicist will tell you the exact same thing I just did.
Anonymous said…

I am not talking about obesity. I am calling out the diet industry on their practice of taking ideas from sceince and running with it.

I am talking about Dr. Gregory Ellis' claim that The First law of Thermodynamics can never be broken and is not able to be vilolated.

That statement is WRONG.

The First law of Thermodynamics HAS been violated - MANY TIMES with Black Holes.

The Big Bang ( which created our natural laws by the way) it self ALSO violates thermodynamics.

In fact. the COSMOLOGY TETXTS are being REWRITTEN from the data we gathered in the last 6 years or so.

Wer live in a MULTIverse.

Yes I HAVE spoken to a real physicist . DR. MICHIO KAKU by email.

Einstein's old model of our UNIverse being a slow movig bubble was WRONG.

NOTHING in science is certain.

There are huge problems with taking a measurement of heat outpout from burning and using it to predict what happens when humans consume a substance .

The human body's processes are not even REMOTELY the same as oxygenation ( burning). The calories within a substance which is burned have very little predictive value in determining their impact on human metabolism

That is EXACTLY what the caloric hypothesis people do.

Obesity is HELLISHLY complex and thermodynamics DO NOT AT ALL EXPLAIN obesity.
Anonymous said…

You chose to rail against rodent studies all the time that CONTRADICT the caloric hypothesis e.g., those featured at MY blog.

Sorry, but you Colpo and James Krieger are all the bioggest cherry pickers ever - some of whom do it for monetary gain.

Yet you accuse Gary of this...

Dr Friedman M.D., Ph.D. and Dr. Linda Bacon Ph.D. are impartial and VERY familiar with the research.
Anonymous said…
Obesity is NOT a simple condition of eating too much , CarbSane. I do not see WHY you cannot grasp this when top experts like Dr. Linda Bacon, Dr Jeffery Friedman, Dr. Fred Turek, Dr. Gordon all ADMIT this.

The reasons behind weight gain are VERY complex.

What the SCIENTISTS are saying is DIFFERENT from what the anti- - Gary Taubes BLOGGERS are saying.

Gary Taubes is a good dude and very nice. He is not omniscient- no one is. But he is conpletely correct in pointing out the FLAWS in the caloric model

Science is moving us - AWAY from the caloric hypothesis. Time will show this.

Sorry if you cannot accept this. That is the reality.

There is nothing left to say.
bentleyj74 said…
"There is nothing left to say."

I'll bet you a shiny nickel you still have more to say :)