Reversing liver damage caused by non-alcoholic fatty liver disease (NAFLD) — a form of hepatitis affecting up to 60 percent of people with obesity and type 2 diabetes — may be difficult to reverse, even with improvements in diet and exercise, according to new findings published in PLOS ONE. However, research also shows a major cut in sugar could be key to better reversing cirrhosis and fibrosis caused by the condition, ScienceDaily reports.

Currently, NAFLD affects between 10 and 35 percent of U.S. adults and an increasing number of children. The condition, which occurs when fat packs into the liver, can cause extensive liver scarring, or fibrosis, which can reduce its capacity to function and can lead to cirrhosis and cancer down the line. There is currently no cure for NAFLD. However, research shows it can be prevented and potentially reversed by healthy lifestyle choices.

For this most recent study, scientists at Oregon State University studied two groups of laboratory mice that were first fed a “Western diet” high in sugar, fat and cholesterol, and then switched to healthier diets. In both groups, fat and cholesterol were reduced, causing significant weight loss and metabolic improvements. However, one group of mice was fed a new “healthy” diet that was still fairly high in sugar. This caused the animals to have significantly higher levels of inflammation, oxidative stress and liver fibrosis than the low-sugar group, even after they lost weight.

Translated to a human model, researchers said the findings could suggest that liver damage caused by NAFLD may be difficult to reverse, even when people take steps to improve their health. In fact, steps like diet and exercise may have a limited effect on slowing down and recovering from pre-existing liver damage unless people don’t also significantly cut sugar out of their diet.

However, researchers also pointed out that until recently, it was believed that NAFLD-related liver scarring was completely irreversible. Fortunately, new studies show that it can at least be partially recovered from with an optimal diet and/or when the stimulus for liver injury (i.e. poor diet, metabolic dysfunction) is removed from the equation. More research is still needed to determine whether any comprehensive diet program, weight loss plan, or drug therapies could fully resolve liver fibrosis.