Researchers show that the effects of a single high-fat meal alters the sensitivity to insulin and changes liver metabolism in a way that may be the first step toward liver disease.
While researchers acknowledge that many healthy people can handle the immediate changes in metabolism, the long-term consequences for those who regularly consume high amounts of saturated fat may be far worse.
The study, “Acute dietary fat intake initiates alterations in energy metabolism and insulin resistance,” was published in January in the Journal of Clinical Investigation.
To investigate how a single high-fat meal impacts the metabolism, researchers at the German Diabetes Center recruited 14 lean, healthy individuals into a clinical trial (NCT01736202). The participants randomly received either a flavored palm oil drink or water. Palm oil is a saturated fat. The drink contained the equivalent amount of saturated fat as two cheeseburgers with bacon and a large portion of French fries, or two pizzas with sliced salami.
The experiments showed that this single intake of a large amount of fat decreased insulin sensitivity by 25% in the entire body. In the liver and fat tissue, the sensitivity decreased by 15% and 34%, respectively. Meanwhile, liver fats increased by 35% and energy content rose by 16%.
The energy processes in the liver were significantly altered, with a 70% increase in glucose produced in the liver from non-carbohydrate sources, and a 20% reduction of glucose storage. In mice, the same procedure triggered extensive gene activity changes in the liver.
Importantly, these changes were similar to alterations in people with type 2 diabetes and non-alcoholic fatty liver disease (NAFLD) — the most common liver condition in the industrialized world.
“The surprise was that a single dosage of palm oil has such a rapid and direct impact on the liver of a healthy person and that the amount of fat administered already triggered insulin resistance,” Prof. Michael Roden, managing director and chairman at the German Diabetes Center and the German Center for Diabetes Research, said in a press release.
“A special feature of our study is that we monitored the liver metabolism of people with a predominantly noninvasive technology,” the magnetic resonance spectroscopy, he said. “This allows us to track the storage of sugar and fat as well as the energy metabolism of the mitochondria (power plants of the cell).”
Such changes prevent skeletal muscles from taking up glucose, mimicking an early stage of type 2 diabetes, researchers explained. Meanwhile, the insulin resistance in fat tissue leads to release of additional fat into the bloodstream, which further contributes to a metabolic syndrome.
The research team suspects that healthy people, particularly if genetics are on their side, can handle a temporary deviation of liver metabolism triggered by a high-fat meal. But for people regularly consuming high amounts of saturated fats, the changes likely pave the way for future liver disease and metabolic problems.