High Fat/Low Carb May Not be the Real Issue

A recent paper in EBioMedicine studied variations on low and high fat and carbohydrate diets. What makes the study interesting is that it was comparing a ‘traditional’ Chinese diet (low fat – high carb) with a more Western (high fat – low carb) diet among Chinese Nationals. The traditional diet resulted in more weight loss without a significant change in LDL or insulin activity. Here are the details:

• Six-month, randomized three-arm trial of three isocaloric diets. Protein represented 14% of energy intake in all three. Fats varied from 20 to 40%, while carbohydrates varied from 66 to 46%.
• Participants ate only the foods provided and avoided excessive or unusual strenuous exercise
• Body weight and waist circumference were the outcomes of interest and were statistically significantly reduced for the lower fat, higher carbohydrate group. Clinical significance may be less given only a 0.6kg difference overall between the groups.
• While all three dietary interventions were associated with decreases in weight, waist circumference, the level of total, LDL, and non-HDL cholesterol, reductions in the LF-HC group were greater than those observed in the MF-MC and the HF-LC groups. HDL cholesterol was also reduced, but there were no differences among groups with regard to total to HDL cholesterol ratio. Insulin and glucose levels remained unchanged throughout the trial.

And they concluded that

In conclusion, among non-obese healthy Chinese, a low fat, relatively high carbohydrate diet, similar in macronutrient composition to traditional dietary patterns in China appears to be less likely to promote excessive weight gain and be associated with a lower cardiometabolic risk profile than a diet more typical of that eaten in Western countries. 

Could this be true? Could it be that the Mediterranean Diet works best for those individuals raised or genetically associated with the Mediterranean? Put another way, do are traditional diets, the ones consumed by our genetic ancestors keep us healthier? The food sources of our ancestors were determined in large part by their geography and were an evolutionary pressure as much as a cultural one. Is a traditional diet a genetic marker? We certainly know that some genotypes have more difficulty processing alcohol or milk.

One of the problems with nutritional studies is that the results are contradictory, this study included. We often attribute these differences to the methodology. Could it be that our groups were too heterogeneous, that we were mixing so many different subtle genetic differences in metabolism that our groups were distinct in a way we did not recognize, an unknown known? Perhaps we should re-sort our groups, and while it might be ideal to do so along genetic lines, I do not believe we have the ability to make those distinctions at this point. In its place, and I think this is the real interesting thought that comes from this paper, should we begin to sort along the lines of traditional diet, along with geographic origin – evolution’s groupings.