Diane W. says her doctors were worried about her health.
At 5 feet, 4 inches, the Bay Area woman weighed 220 pounds. Any physical activity would leave her out of breath.
"I'd hike up a hill here in San Mateo or go on a hike up San Bruno Mountain. Usually everybody else was ahead of me. I made it up there. I plodded up there. But it was sort of pathetic."
When doctors diagnosed nonalcoholic fatty liver disease – now known as metabolic dysfunction-associated steatotic liver disease (MASLD) – she knew something had to change. She’d always tried to be active, but her weight undermined her confidence, says Diane, who didn’t want to use her full name to protect her privacy while sharing her medical information.
She went to her health care provider, and they helped her design a program that combined hand weights, online exercise videos, Zumba dance classes, and weight loss medications. As she implemented the program, she found she could hike farther, and she grew more confident about her routine.
Since then, her body fat has dropped from 47.9% to 36.2% and she feels stronger, she says, because she lost more fat than muscle with all the exercise. Her blood sugar, triglycerides, and cholesterol levels improved so much that her doctor took her off statins.
It doesn’t require high-intensity effort, says Lydia Alexander, MD, president of the Obesity Medicine Association. Something as simple as sitting and standing repeatedly or going for a 5-minute walk can make a difference, she says.
"So even right now as we're talking, I'm pacing and so I'm getting some steps in,” says Alexander. “And that's really helpful."
Exercise and Fatty Liver: How It Works
Weight gain is a major cause of excess liver fat. Nearly three quarters of U.S. adults ages 25 and up weighed enough to be classified as overweight or obese in 2021, according to a recent article in The Lancet. Fewer than 5% of people who have fatty liver disease know about it, in part because symptoms often remain hidden and also because many doctors tend to underestimate its prevalence.
Fatty liver disease develops slowly. Long stretches of excess nutrients like fat and glucose in the blood -- whether from diet, inactivity, stress, infection, or other causes -- can overwhelm your liver. These extra nutrients are stored as fat in the liver.
Exercise can help restore balance, starting with muscle. Muscle is the body’s biggest user of glucose, the main sugar in your blood, and physical activity prompts the liver to burn more fat and convert it to fuel for muscles. Exercise also increases metabolism and cardiovascular health, making it easier to burn fuel with aerobic exercise.
That helps keep fat from building up in your liver. It also helps control blood sugar (glucose).
"Think of muscle like an engine in a car,” says John Thyfault, PhD, professor of cell biology and physiology at the University of Kansas Medical Center. “If it's not running, it's not using the glucose. Then the car says, 'Why are you putting more glucose into me? My tank is full.'"
Over time, this can lead to a problem called insulin resistance, in which the body stops storing excess glucose, instead leaving dangerously high levels of sugar in the blood. (High blood sugar is associated with a number of serious medical conditions including nerve damage, diabetes, and liver disease.)
"There is no doubt that poor insulin sensitivity, or what we call insulin resistance, really drives liver fat storage," says Thyfault. "You can take someone who is insulin resistant and have them exercise every day for three to seven days and it will improve."
The effect of exercise, even if you do nothing else to manage your fatty liver, can be profound, says Ray Kim, MD, president of the American Association for the Study of Liver Diseases. "Most of our patients, if they were hitting gyms seven days a week, they probably would not be in my office.”
But experts are careful to point out that diet matters at least as much as exercise.
Highly processed food is loaded with calories that cause fat to build up in the liver, says Robert Lufkin, MD.
It takes a couple of minutes to down a 500-calorie muffin, Lufkin writes in his book, Lies I Taught in Medical School. That many calories would fuel 40 minutes of running, which in turn, he notes, would make you hungry. “You can’t outrun a bad diet.”
Exercise: How Much and What Kind?
Short answer: Any kind of physical activity will do. Just get moving.
Longer answer: Different types of exercise are effective in different ways. Aerobic training, such as jogging, burns fat and shifts storage of it away from the liver, Lufkin says. Resistance training, such as weightlifting, increases muscle mass, causing healthy changes in metabolism.
But it matters less how you exercise than how often.
Most studies have shown that programs of 30 to 60 minutes per day, three times a week over 12 weeks will reduce liver fat, says Anastasia-Stefania Alexopoulos, MBBS, assistant professor of endocrinology, metabolism, and nutrition at the Duke University School of Medicine. “The most important goal is to avoid being sedentary.”
And intensity may matter less than consistency.
People who added a bit of jogging to their brisk walking routine lost no more liver fat than those who did just brisk walking, according to research from The American Association of Clinical Endocrinology.
Thyfault says weight loss isn’t the main goal of exercise, though it does help to prevent weight gain. The main benefit is health, he says. Exercise can help improve fatty liver disease even if you don’t see a downward movement on the scale, he says – by increasing muscle, burning more glucose, and improving insulin resistance.
He advises eating more protein to help limit the loss of muscle that inevitably accompanies weight loss from eating less and eating healthier. He also recommends scheduling workouts with friends for accountability. Knowing that people are waiting for you before starting a run or a bike ride may be the psychological push you need to get out the door.
He says workout intensity is relative. Those who are fitter might want to run fast for four minutes and then cool down with a walk. Others might just want to walk down the hallway.
‘This Is a Priority ’
Today, Diane W. says she is 70 pounds lighter than when she started her weight loss program.
"Make exercise a priority in your life. That was the mind shift for me," she says. Being a mom, a wife, and a worker slowed her body down, but now that her time is hers, she chooses to move it vigorously.
“This is a priority pretty much on a daily basis,” she says. “I get up and I go to the Y. Your mind is like, 'Oh, you're tired, you don't need to go.'”
“No,” she says. “I just go."
