Monday, October 1, 2007

Metabolic Advantage of Low Carb Diets

Dr Eades has done an outstanding post proving that there truly is a metabolic advantage of following a low carb diet.

Karl Popper, metabolic advantage and the C57BL/6 mouse | Health & Nutrition by Michael R. Eades, M.D.

It is a very long read. But hey, this is science, it takes that to really explain it all. One part really stood out for me, the mouse study.

Now I’ve written many, many times over the course of this blog that rats and mice are not just furry little humans. Many experimental results from these animals don’t work the same way with humans, so you’ve got to be careful what you accept as valid as far as humans are concerned. But the laws of thermodynamics DO work the same in all living creatures and in all systems for that matter. So rats or monkeys or mice or armadillos are going to obey the laws of thermodynamics in the same way we humans do. And thermodynamic data we gather from well done animal studies applies to humans just as it does to the animals in question.

A couple of months ago a group from Harvard published a study in the prestigious American Journal of Physiology looking at what happens when diet composition is varied in mice, C57BL/6 mice to be exact.

The researchers divided 32 genetically-identical, 8-week old male mice into 4 groups of 8. Each group was put on a different diet. One group got a high-sucrose, high-fat diet (lucky little buggers since they were all going to die anyway), another got a control diet of regular chow, another got a chow diet that was only 66% of the calories of the control chow diet and the last group got a very-low-carbohydrate ketogenic diet. All the mice got the same number of calories that varied with growth. Here’s how that worked out.

The control mice eating the chow set the caloric consumption for the group. Researchers gave the control mice all the chow they wanted and measured the calories consumed. They then gave that same number of calories to the high-sugar, high-fat group and to the ketogenic diet group. They gave 66% of the control diet calories to the calorically-restricted group. They studied the mice for a little over a month, which is a long time in the life of a mouse.

What were the findings?

The researchers discovered that despite eating the same number of calories as the control mice and the high-sugar, high-fat mice, the mice on the ketogenic diet gained weight at the same rate as those on the calorically-restricted diet. (Remember, mice, unlike humans, continue to grow throughout their short lives, and so will continue to gain weight.) Here is the weight change portrayed graphically.

As you can see from A above, the mice on the ketogenic diet ate the same number of calories as all the other mice did except for the calorically-restricted ones. You can see from B that the mice on the ketogenic diet weighed the same as the calorically-restricted mice despite consuming many more mousy calories. And, finally, you can see from C that the laws of thermodynamics weren’t violated because the mice on the ketogenic diet ran at a hotter temperature than did the other mice.

And I find it curiouser and curiouser that the very diet that provided the metabolic advantage to these mice, the ketogenic diet, is the same diet that has been shown to provide a metabolic advantage to humans.

Intelligent people will look at this tightly-controlled study and say, Hmm, mice that ate a ketogenic diet gained less weight than genetically-identical mice eating the same number of calories but of a different composition. There must be something different about the way a ketogenic diet works because it provides a metabolic advantage, i.e., the animals that followed it gained less than those that didn’t and didn’t do anything volitional to keep from gaining the weight.

At least that’s what the authors of the study said. And one assumes that they are reasonably intelligent. Specifically, they concluded that

feeding of a ketogenic diet with a high content of fat and very low carbohydrate leads to distinct changes in metabolism and gene expression that appear consistent with the increased metabolism and lean phenotype seen. Through a specific dietary manipulation, weight loss can occur secondary to distinct metabolic changes and without caloric restriction. [My italics]

It sounds like a metabolic advantage to me. It sure does. It sure does.

These authors have done other studies with this same strain of mice and found the following:

These data indicate that dietary manipulation is capable of altering energy balance and metabolic state. In these experiments a high-fat, ketogenic diet not only failed to cause obesity but was capable of reversing diet-induced obesity in mice. These data suggest a more complex relationship between fat consumption and obesity than previously thought. Further investigation as to the mechanisms of energy balance in these animals may provide new targets in obesity research.

So, we’ve come full circle. Using the data from these mouse studies we have shown that there indeed is a metabolic advantage in living creatures that doesn’t violate the laws of thermodynamics, and by doing so have falsified the hypothesis (vigorously stated by some) that there is no metabolic advantage. Meaning, of course, that there is indeed a metabolic advantage, which anyone with good sense who has fooled around with low-carb diets realizes.

So this can explain to many of the nay sayers still entrenched--- the-low-fat-calories-do-count-gotta-exercise-all the time--- mind set---to think again. It is something, luckily, I have known for quite some time.



Anonymous said...

Welcome back! Glad to see you're here again with another great posting! Didn't that article encourage you lots? I kept smiling to myself as I waded through the scientific mumbo-jumbo--this is such good reading, and mind-calming! Eating those steaks keeps getting better and better for me.
Now I have to (as per your last sentence) figure out which foods are mostly fat (in a fat/protein ratio, I guess) and bring 'em into the diet plan! I know avocados are one of the best things one can eat on a ketogenic diet--what other suggestions do you have?
Thanks Bama!!

Alcinda (Cindy) Moore said...

"the-low-fat-calories-do-count-gotta-exercise-all the time"
When you're eating low fat (high carb)the calories DO count and you MUST exercise or you won't loose....but low carb high fat (or high protein) you can eat more and don't have to exercise as much.

Heck, with low carb many of us are/were unable to do much as exercise for the first 20, 30, 50 (or more) pounds!!

While not a healthy diet, low fat diets are effective for those that only have 10 or 15 pounds to loose....but for those of us that are more overweight, obese or even morbidly obese it's too hard to stick with over the long term, unlike low carb.

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