Monday, December 04, 2006

Can Low-Carb Evolve Into Making You Fat?

Eight generations of caterpillars may prove low-carb is for naught

The opponents of livin' la vida low-carb are at it again and this time they've gone out of their way to be just about as absurd in their opposition as I've ever seen them when it comes to interpreting scientific research data in a way that attempts to discredit the Atkins/low-carb lifestyle as a healthy long-term option for weight loss and improved health.

This column in the Texas A&M University student newspaper The Battalion points out a recent study supposedly showing that future generations of caterpillars placed on a low-carb, high-protein diet eventually begin storing fat while the bodies of the ones put on a high-carb diet actually adapt to the increased carbohydrate intake.

Dr. Spencer Behmer, assistant professor of Insect Physiology from the Department of Entomology at Texas A&M University, in collaboration with researchers from Oxford University in the UK, The University of Sydney in Australia, and The University of Auckland in New Zealand, wanted to see what role diet would have on future generations of caterpillars in an attempt to extrapolate information that may be applicable to human beings in the future. Read the PubMed synopsis of this study by clicking here.

They split 400 Plutella xylostella caterpillars into two groups:

1. High-protein/low-carb diet
2. High-carb/low-protein diet

Each of the two sets of 200 caterpillars were provided with 100 blocks of "artificial food" comprising the specified macronutrient level for their particular group. Each of the groups were monitored for how they adapted to their surroundings while eight generations (equivalent to 160 human years) of the caterpillars were observed eating the food that was available to them.

"While one set of caterpillars lived on a South Beach or Atkins diet, the other 200 binged on a high calorie carbohydrate diet, like living on potato chips and Coca-Cola," Dr. Behmer explained.

Dr. Behmer and the other researchers fully expected the high-protein/low-carb diet group to lower their body fat and be skinny by the time the eighth generation of offspring had matured. But instead they noticed the bodies of the caterpillars in this group actually were able to use the limited amount of carbohydrates they did consume to begin storing fat reserves. Conversely, the caterpillars on the high-carb/low-protein diet experienced a change in their metabolism that actually adapted to the higher carbohydrate intake by not storing as much of it as fat.

All I have to say to this, Dr. Behmer, is SO WHAT?! Is this supposed to prove something that maybe I'm just not smart enough to figure out? A caterpillar eating a low-carb diet in a laboratory experiment cannot possibly be used to predict how humans will react to a being placed on a similar diet. Is that what you are saying?

That's exactly what he's saying!

"[Caterpillars and humans] share the same nutritional requirements," Dr. Behmer stated explaining the diet of caterpillars is close to humans because both eat protein, carbohydrates, and fat.

As a result, Dr. Behmer believes we can make the leap of faith that this study should also apply to humans and act accordingly. Basically what he is assuming is anyone who is livin' la vida low-carb right now will eventually see their great-great-great grandchildren beginning to GAIN weight on low-carb so long as they all continue eating that way. How ridiculous is that anyway?! Who expects their future bloodline to eat like they do today anyway?

But not so fast on the side-by-side comparison of caterpillars to humans says Dr. Jeff Volek, low-carb diet reearcher from the University of Connecticut. When I asked him to comment on the relevance to humans this study of caterpillars has, his response back to me was "you have to be joking."

"I look at rat data very cautiously because even with rodents there are so many differences in metabolism and limitations in generalizing to humans (even though its done all the time)," Dr. Volek remarked. "But caterpillars? As John Stossel would say 'give me a break'."

There was an even stronger reaction from noted low-carb diet research scientist Dr. Richard Feinman from SUNY Downstate In Brooklyn, New York and co-editor-in-chief of the scientific journal Nutrition & Metabolism. He adds a rather unique perspective to this conversation that brings a fresh sense of reality back into the discussion.

"Isn't the normal diet of caterpillars all high-carb and high cellulose at that? In other words, I thought they can actually live on fiber that, for humans, goes straight through our bodies. This seems like the worst model for human metabolism. On the other hand, I have not quite gotten over the fact that, late in life, I did not turn into the equivalent of a butterfly."

I think Dr. Feinman is a stand-up comic when he's not researching! :)

Fellow low-carb blogger Regina Wilshire (who I will be publishing an interview with along with her husband Dr. Gil Wilshire very soon) from the "Weight Of The Evidence" blog said "this article doesn't do [the study] justice."

"Dr. Behmer failed to say when the low-carb caterpillar group ate a diet high in carbohydrate again," Wilshire explained after looking at the full text of the study. "Just eating what they'd eaten for generations wasn't making them heavy, it was switching their diet back after generations to a higher carbohydrate load. It was the same with the high-carb caterpillar group which changed their diet and gained too. That's something that was conspicuously absent in the article as well."

Interestingly, Dr. Behmer does admit the high consumption of sugar and excessive starchy carbs that is typical of the Standard American Diet has led to the current obesity crisis in America. But he said there is a psychological component to human obesity that cannot be captured by the caterpillars.

"Obesity is not just a diet thing, it also affects an individual's activity," Dr. Behmer said. "For example, an obese person would rather drive than walk."

So, the fatter we get, the less apt we are to want to get enough exercise for our bodies to burn off the excess calories we are consuming. And the vicious cycle continues. I'm not sure what to think about this whole idea that several generations of family members doing low-carb over a period of time eventually makes the later generations obesity-resistant and inevitable to gain weight on a low-carb diet.

Even if it is 100 percent accurate, is it even realistic to think our ancestors who come after us would even eat the same way that we do. Not likely. Especially when they get in the rebellious teenage years. I can see it now: "No, mom, I'm not going to have that steak and salad supper, I'm going to Mickey D's for a Super Duper Big Mac, and a 1 gallon bucket of French fries followed by a keg of Coke. Take THAT with your low-carb diet!" LOL! It's too far-fetched to even think about.

The results of this study were published in the Proceedings of the National Academy of Science.

You can e-mail Dr. Spencer Behmer at

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Blogger Calianna said...

Assuming we ignore what Regina said about the weight gain only happening when the caterpillars were put back on a high carb diet after several generations on a low carb diet...

And assuming we ignore what Dr. Feinman said about the normal diet of caterpillars...

Even if we ignore those inconvenient little facts, he'd still rather we eat a diet that makes us feel awful and causes us to gain inordinate amounts of weight, on the off chance that some future generation might develop some kind of resistance to the effects of our generation low carbing?

Yeah, that's what it sounds like.

I can hear it now...

"This low carb thing may be working for you right now, and yeah, it looks like it'll work your entire life, and yeah, it looks like it'll even work for several generations... but just you wait! [waggles finger in your face for effect] There's going to come a time when it won't work so well for some future generation!"

The mind boggles.

12/04/2006 7:29 PM  
Blogger Science4u1959 said...

Another candidate for my Darwin Award. A lovely example of bad science... indeed, mindboggling.

12/06/2006 11:26 AM  

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