It was probably enough to make many Americans lose their appetite: A recent study from Europe showed that eating too much fast food – a diet high in fat and sugar – could cause serious damage to your liver.

Yet for those who overdo it with too many trips to their favorite burger joint, there’s good news. You can likely reverse the damage to your liver and other vital organs if you simply give up the unhealthy lifestyle, according to a leading liver specialist at Saint Louis University who conducted a similar study with mice.

“There’s strong evidence now that a fast-food type of diet – high in fat and sugar, the kind of diet many Americans subsist on – can cause significant damage to your liver and have extremely serious consequences for your health,” says Brent Tetri, M.D., professor of internal medicine at the Saint Louis University Liver Center and one of the country’s leading experts on non-alcoholic fatty liver disease.

“The good news is that most people can undo this damage if they change their diet and they keep physically active,” Tetri says. “If they don’t, however, they are asking for trouble.”

Particularly alarming, says Tetri, is that physicians are starting to see children and teenagers with cirrhosis, a serious liver disease once seen mostly in adults with a history of alcohol abuse or hepatitis C. Tetri suspects this is because many kids today eat far too much fast food or junk food and get far too little exercise – the kind of behaviors that can lead to liver damage.

“The fact we’re starting to see kids with liver disease should really be a wake-up call for anyone eating a diet high in fat and sugar and who’s not physically active,” Tetri says.

Tetri last year studied the effects on mice of a diet that mimicked a typical fast-food meal. The diet was 40 percent fat and replete with high-fructose corn syrup, a sweetener common in soda and some fruit juices. The mice were also kept sedentary, mimicking the lifestyle of millions of Americans.

The result: Within four weeks, the mice displayed an increase in liver enzymes – a key indicator of liver damage – and the beginnings of glucose intolerance, a marker for type II diabetes.

Similarly, in February researchers in Sweden published the results of a study in which 18 healthy and slim adults ate fast food and restricted their physical activity for a month. The result: an average weight gain of 12 pounds and, within as little as a week, a sharp rise in liver enzymes.

Tetri is quick to emphasize that fast food per se doesn’t causes liver damage. Rather, he says, the harm comes from eating too many calories and too much fat and sugar – which happens with a steady diet of burgers, fries, sodas and most other items on the typical fast-food menu.

“The big issue here is caloric content,” says Tetri. “You can put away 2,000 calories in a single fast-food meal pretty easily. For most people, that’s more calories than they need in an entire day.”

For adults and children who’ve repeatedly indulged in fast food, Tetri urges four key steps to help reverse the damage they’ve done to their liver.

1. Limit yourself to no more than one fast-food meal a week. For some people, that’s going to be a major downshift. But for the sake of your health, a visit to a fast-food restaurant should be considered a treat – not a regular event.

2. When you do eat fast food, eat as healthfully as possible. Try the burger without mayo and cheese, and avoid fries and sugary soft drinks. Better yet, go for a grilled chicken sandwich, a salad with a lower-fat dressing and bottled water or a diet soft drink.

3. Get active. If you don’t already exercise at least three times a week, start now. Regular exercise helps keep your weight down and helps your body better metabolize and process the food you eat.

4. Ask your doctor to do a blood test to check your level of liver enzymes, a key measure of the health of your liver. Many doctors now order test this routinely when doing blood work on adults, but kids who eat a lot of fast food especially need to have their liver enzymes checked.

“Even for those people with the worst kind of diets, it’s not too late to start exercising and eating right,” Tetri says.

Established in 1836, Saint Louis University School of Medicine has the distinction of awarding the first medical degree west of the Mississippi River. The school educates physicians and biomedical scientists, conducts medical research, and provides health care on a local, national and international level. Research at the school seeks new cures and treatments in five key areas: cancer, liver disease, heart/lung disease, aging and brain disease, and infectious disease.

Source: Saint Louis University Medical Center