Note in reading this that a key difference between the paleo diet and the Mediterranean (and American) diet is that paleo cuts out flour, grains, and sugar.
On to the results. Participants, on average, saw large improvements in nearly every meaningful measure of health in just 10 days on the “paleolithic” diet. Remember, these people were supposedly healthy to begin with. Total cholesterol and LDL dropped, if you care about that. Triglycerides decreased by 35%. Fasting insulin plummeted by 68%. HOMA-IR, a measure of insulin resistance, decreased by 72%. Blood pressure decreased and blood vessel distensibility (a measure of vessel elasticity) increased. It’s interesting to note that measures of glucose metabolism improved dramatically despite no change in carbohydrate intake. Some of these results were statistically significant, but not all of them. However, the authors note that:
In all these measured variables, either eight or all nine participants had identical directional responses when switched to paleolithic type diet, that is, near consistently improved status of circulatory, carbohydrate and lipid metabolism/physiology.
Translation: everyone improved. That’s a very meaningful point, because even if the average improves, in many studies a certain percentage of people get worse. This study adds to the evidence that no matter what your gender or genetic background, a diet roughly consistent with our evolutionary past can bring major health benefits. Here’s another way to say it: ditching certain modern foods can be immensely beneficial to health, even in people who already appear healthy. This is true regardless of whether or not one loses weight.
There’s one last critical point I’ll make about this study. In figure 2, the investigators graphed baseline insulin resistance vs. the change in insulin resistance during the course of the study for each participant. Participants who started with the most insulin resistance saw the largest improvements, while those with little insulin resistance to begin with changed less. There was a linear relationship between baseline IR and the change in IR, with a correlation of R=0.98, p less than 0.0001. In other words, to a highly significant degree, participants who needed the most improvement, saw the most improvement. Every participant with insulin resistance at the beginning of the study ended up with basically normal insulin sensitivity after 10 days. At the end of the study, all participants had a similar degree of insulin sensitivity. This is best illustrated by the standard deviation of the fasting insulin measurement, which decreased 9-fold over the course of the experiment.
Interesting. Read the whole thing.
In “Paleolithic Diet Clinical Trials,” Stephan says:
After 12 weeks, both groups improved on several parameters. That includes fat mass and waist circumference. But the paleolithic diet trumped the Mediterranean diet in many ways:
* Greater fat loss in the the midsection and a trend toward greater weight loss
* Greater voluntary reduction in caloric intake (total intake paleo= 1,344 kcal; Med= 1,795)
* A remarkable improvement in glucose tolerance that did not occur significantly in the Mediterranean group
* A decrease in fasting glucose
* An increase in insulin sensitivity (HOMA-IR)
Overall, the paleolithic diet came out looking very good. But I haven’t even gotten to the best part yet. At the beginning of the trial, 12 out of the 14 people in the paleo group had elevated fasting glucose. At the end, every single one had normal fasting glucose. In the Mediterranean group, 13 out of 15 began with elevated glucose and 8 out of 15 ended with it. This clearly shows that a paleolithic diet is an excellent way to restore glucose control to a person who still has beta cells in their pancreas.
Fascinating. Read the rest!!