A large study of over 20,000 Americans found that people who eat higher-quality diets are less likely to develop a common liver condition called fatty liver disease (MASLD). Researchers looked at three different healthy eating patterns—the Healthy Eating Index, Mediterranean diet, and DASH diet—and found that each one was linked to a lower risk of fatty liver disease and serious liver damage. The study also showed that people with better diets lived longer overall. However, the benefits for people who already had fatty liver disease were less clear, suggesting that prevention through good eating habits may be more powerful than trying to reverse the disease once it develops.

The Quick Take

  • What they studied: Whether eating a healthier diet could help prevent fatty liver disease and reduce the risk of serious health problems in American adults
  • Who participated: Over 20,000 American adults from a national health survey conducted between 2005 and 2020, representing different ages, backgrounds, and health conditions
  • Key finding: People who improved their diet quality by one standard amount had about 25-31% lower chances of developing fatty liver disease, depending on which healthy diet pattern they followed
  • What it means for you: Eating better foods now may help you avoid fatty liver disease in the future. The three diet patterns studied (Mediterranean, DASH, and Healthy Eating Index) all showed similar benefits, so you can choose whichever approach works best for your lifestyle. However, if you already have fatty liver disease, diet improvements may help slow damage but may not reverse the condition completely.

The Research Details

This study used information from a large national health survey called NHANES that has been tracking American health since 2005. Researchers looked at two groups: one with about 20,500 people at a single point in time (cross-sectional), and another with about 13,000 people they followed for an average of 9.3 years (longitudinal). They measured diet quality using three different scoring systems that rate how healthy someone’s eating patterns are based on foods they eat. They identified fatty liver disease using special scoring methods that don’t require a liver biopsy, and they tracked who died during the follow-up period using national death records.

This research approach is important because it uses real-world data from thousands of Americans rather than a small laboratory study. By following people over time, researchers could see whether better eating habits actually led to better health outcomes and longer lives. Using multiple diet scoring systems strengthens the findings because it shows the results aren’t dependent on just one way of measuring healthy eating.

This study has several strengths: it includes a very large number of people, uses nationally representative data, and follows people over many years. However, the study is observational, meaning researchers watched what people naturally did rather than randomly assigning them to different diets. This means we can’t be completely certain that diet caused the benefits—other healthy habits might have played a role. The study also relied on people remembering what they ate, which can be imperfect.

What the Results Show

The study found that each improvement in diet quality score was linked to meaningful reductions in fatty liver disease risk. When people improved their Healthy Eating Index score by one standard amount, their chances of having fatty liver disease dropped by 25%. The Mediterranean diet and DASH diet showed even stronger protection, with 25% and 31% reductions respectively. These benefits held true across different age groups and backgrounds. For people who already had fatty liver disease, better diet quality was associated with 17-22% lower chances of developing advanced liver scarring (fibrosis), which is a serious complication. Over the 9+ year follow-up period, people with higher diet quality scores had lower death rates from all causes combined, with reductions ranging from 7-11% depending on which diet pattern was measured.

The study revealed important differences between people with and without existing fatty liver disease. In people without fatty liver disease, the protective effects of better diet quality on overall mortality were clear and consistent. However, in people who already had fatty liver disease or advanced scarring, the mortality benefits were less obvious. This suggests that while good eating habits are excellent for prevention, they may work differently once the disease has already developed. The study also found that all three diet patterns (Mediterranean, DASH, and Healthy Eating Index) showed similar benefits, indicating that multiple approaches to healthy eating can be effective.

This research builds on growing evidence that diet quality matters for liver health. Previous smaller studies suggested that Mediterranean and DASH diets might help with fatty liver disease, but this is one of the largest studies to confirm these benefits in a nationally representative American population. The finding that prevention appears more effective than treatment aligns with what doctors know about many chronic diseases—it’s easier to prevent problems than to fix them once they’ve started. The study also adds new information by showing that these diet benefits extend to overall survival, not just liver health.

The main limitation is that this study observed what people naturally did rather than randomly assigning them to different diets, so we can’t prove diet caused the benefits. People who eat healthier often exercise more, don’t smoke, and have other healthy habits that could explain the benefits. The study relied on people remembering what they ate, which can be inaccurate. Additionally, the study identified fatty liver disease using scoring systems rather than imaging or biopsies, which could miss some cases or misidentify others. Finally, the study included mostly American adults, so results may not apply to other populations with different genetics or food availability.

The Bottom Line

Start improving your diet quality now by focusing on whole foods like vegetables, fruits, whole grains, legumes, and lean proteins while reducing processed foods, added sugars, and unhealthy fats. You can follow any of the three diet patterns studied (Mediterranean, DASH, or Healthy Eating Index) since they all showed benefits—choose whichever fits your preferences and lifestyle best. These recommendations are appropriate for most adults interested in preventing fatty liver disease and living longer. If you already have fatty liver disease, improving your diet is still important and may slow disease progression, but you should work with your doctor on a comprehensive treatment plan. (Confidence level: Moderate—based on large observational study but not a randomized controlled trial)

Everyone should care about this research, especially people with risk factors for fatty liver disease such as obesity, diabetes, or metabolic syndrome. People with a family history of liver disease should pay special attention. If you already have fatty liver disease, this research suggests diet improvements are worth pursuing but may need to be combined with other treatments. People without any liver disease should view this as motivation to eat better for overall health and disease prevention. Younger people may benefit most since they have more time to prevent disease development.

You may notice some benefits like improved energy and better digestion within weeks of improving your diet. However, measurable improvements in liver health typically take several months to a year of consistent healthy eating. If you’re trying to prevent fatty liver disease, the protective benefits appear to build over time, with the study showing clear benefits over years of follow-up. Don’t expect overnight changes—think of this as a long-term investment in your health.

Want to Apply This Research?

  • Track your daily Healthy Eating Index score by logging the number of servings of vegetables, fruits, whole grains, and lean proteins you consume, aiming for specific daily targets. Alternatively, use a simple Mediterranean diet checklist marking off foods like olive oil, fish, legumes, and whole grains consumed each day.
  • Set a specific, measurable goal such as ’eat 5 servings of vegetables daily’ or ‘include fish twice per week’ rather than vague goals like ’eat healthier.’ Use the app to plan meals in advance and receive reminders to prepare healthy snacks, making it easier to stick to your chosen diet pattern.
  • Review your diet quality score weekly and track trends over months rather than days. If available, pair dietary tracking with periodic health markers like weight, energy levels, or lab work (with your doctor’s guidance) to see real-world benefits. Set monthly challenges to try new healthy recipes or increase variety in plant-based foods to maintain motivation and ensure nutritional completeness.

This research suggests associations between diet quality and fatty liver disease risk but does not prove that diet changes will prevent or cure fatty liver disease in any individual. If you have been diagnosed with fatty liver disease, advanced fibrosis, or any liver condition, consult with your healthcare provider or hepatologist before making significant dietary changes. This information is for educational purposes and should not replace professional medical advice, diagnosis, or treatment. Always speak with your doctor before starting a new diet, especially if you take medications or have existing health conditions.