A recent study has purportedly found “for the first time a link between excess dietary sugar and the accumulation of liver fat by DNL [de novo lipogenesis],” the process by which simple sugars like fructose or glucose are converted in the liver into SFA palmitate. Ksenia Sevastianova, et al., “Effect of short-term carbohydrate overfeeding and long-term weight loss on liver fat in overweight humans,” American Journal of Clinical Nutrition, October 2012. After placing 16 overweight subjects on a high-calorie diet for three weeks and then a low-calorie diet for six months, researchers reported that carbohydrate overfeeding induced an approximately 10-fold “greater relative change in liver fat (27%) than in body weight (2%),” with the increase in liver fat proportional to DNL.
Based on these findings, the study’s authors concluded that “short-term overfeeding with simple carbohydrates markedly increases liver fat and stimulates DNL in overweight subjects.” They also noted that, although the changes were reversible with weight loss, “these data support a role for excess simple sugar intake in the pathogenesis of NAFLD [nonalcoholic fatty liver disease].”
“[T]he results provide the impetus for the measurement of liver and plasma triglycerides and DNL after a carbohydrate challenge in a larger number of ethnically diverse subjects tested for genes associated with fatty liver,” explained a concurrent editorial highlighting the study’s conclusions. “In this way, the genetic heterogeneity of the lipogenic effects of dietary sugar will be defined. Dietary recommendations to restrict sugars can then have a stronger scientific rationale and target those at greatest risk and the specific mechanism or mechanisms responsible.”