Another reason to reduce saturated fat in your diet: It’s worse for your liver than unsaturated fat, according to a study published in August 2018 of 38 overweight or obese people without diabetes.
Those who consumed an extra 1,000 calories a day of mostly saturated fat (from cheese, butter, and coconut oil supplied by the researchers) had a 55 percent increase in liver fat after three weeks, compared to a 15 percent increase in those who ate 1,000 extra calories from unsaturated fat (olive oil, pesto, pecans), independent of changes in body weight, which was about 2½ pounds, on average. The diet high in saturated fat also increased insulin resistance.
A third group that consumed 1,000 extra daily calories from sugar (in sugar-sweetened drinks, orange juice, and candy) had a 33 percent increase in liver fat, indicating that excess sugar harms the liver, too.
High liver fat is a sign of nonalcoholic fatty liver disease (NAFLD) and occurs even in people who are not obese. NAFLD, which is on the rise in the U.S., is a risk factor for progressive liver disease as well as diabetes and heart disease.
“The current study shows that saturated fat is the most harmful dietary constituent regarding [liver fat] accumulation.” Similarly, a 2014 study found higher levels of liver fat in young normal-weight adults who were overfed muffins high in saturated fat than in those overfed muffins high in polyunsaturated fat, despite the same weight gain in each group.
Also see Be Wary of Liver Supplements.
This article first appeared in the UC Berkeley Wellness Letter.