Levels of palmitoleic acid – a fatty acid associated with obesity, insulin resistance, and heart disease – decreased in all of the participants during the high-fat/low-carb diets. In contrast, the acid was found to increase as the levels of carbohydrates progressively rose across the duration of the study.
Increases in palmitoleic acid indicate that more carbs are being converted to fat instead of being burned as fuel, states Prof. Volek. In contrast, reducing carbs and increasing dietary fat in a well-controlled way ensures that the body will burn the saturated fat as fuel, rather than storing it in the body.
Misunderstanding about dietary saturated fat is ‘not smart’
The study authors hoped to discover at which point in the increased intake of carbs that the participants began to store fat in their bodies rather than burning it off. Although palmitoleic acid levels increased in all participants, the moment when fat began to be stored varied widely. This finding supports the idea that individual tolerances to carbs can be dramatically different.
Prof. Volek says that there is widespread misunderstanding about saturated fat, stating that despite population studies failing to find a link between dietary saturated fat and heart disease, dietary guidelines continue to advocate restriction of saturated fat:
“That’s not scientific and not smart. But studies measuring saturated fat in the blood and risk for heart disease show there is an association. Having a lot of saturated fat in your body is not a good thing. The question is, what causes people to store more saturated fat in their blood, or membranes or tissues?”
The authors acknowledge that the study is limited by the relatively short timeframe that the diets were followed for. However, a small number of the participants were given the diets in reverse order, starting with the highest carb diet, and the same observations regarding palmitoleic acid were made.
“A higher proportion of plasma saturated fat is related to increased risk of diabetes and heart disease,” conclude the authors. “Thus, there is a need to better understand the relationship between dietary and plasma saturated fat.”
Recently, Medical News Today reported on an analysis of clinical trials for four popular diets, questioning the long-term bene