Increasingly, it’s showing up in people in their 20s and 30s—individuals who don’t drink excessively, don’t appear outwardly unhealthy, and often have no idea their liver is under stress. The condition, now referred to as metabolic dysfunction-associated steatohepatitis (MASH), is emerging as a quiet epidemic, and diet and gut health are playing a larger role than many realize.

As a gastroenterologist, I’ve observed a shift in the demographics of liver disease. What once seemed confined to middle-aged patients with obesity or diabetes is now showing up in younger adults with fewer traditional risk factors. And yet, this trend is flying under the radar—both in public health messaging and often within medical practice.

The early stages of fatty liver disease are typically asymptomatic. Liver enzymes might be only mildly elevated, if at all, and imaging often isn’t done until there are other health concerns. But the damage starts long before it’s visible, and by the time fibrosis or cirrhosis sets in, the opportunity for early intervention has often passed.

Gut reaction: the microbiome relationship

One of the most important—yet overlooked—factors driving the MASH epidemic is gut health. The gut and liver are intimately connected through what’s known as the gut-liver axis. When the gut microbiome is imbalanced—a state called dysbiosis—it can trigger inflammation throughout the body, including the liver.

Dysbiosis leads to increased intestinal permeability, commonly referred to as “leaky gut,” allowing harmful substances like endotoxins to enter the bloodstream and travel directly to the liver. This process contributes to the development of hepatic inflammation and fat accumulation, two hallmarks of MASH.

And what promotes dysbiosis? The modern Western diet—characterized by ultra-processed, high-sugar, low-fiber foods—creates the perfect storm. Diets rich in additives, emulsifiers, and artificial sweeteners can alter microbial diversity, reduce beneficial bacteria, and foster a pro-inflammatory state.

In this context, fatty liver disease isn’t just about excess calories or body mass index (BMI). It’s about the quality of the food and its impact on the gut ecosystem. This explains why some younger, non-obese patients develop MASH while others with higher BMIs may not. The gut microbiome is a missing piece in the metabolic health puzzle.

Why it matters now

The presence of MASH in a young adult isn’t a rare finding anymore—it’s a red flag. If unaddressed, it can progress to cirrhosis, hepatocellular carcinoma, and the need for liver transplantation, often within two decades of onset. These patients also face an increased risk of type 2 diabetes, heart disease, and other complications that compound the burden of illness.

Despite this, routine screening for fatty liver disease is not yet standard practice, even for at-risk individuals. Many patients are never educated about the condition until it has significantly progressed. And because the term “fatty liver” sounds benign, the urgency of intervention is often lost.

The reality is that fatty liver disease is modifiable—especially in its early stages. The liver has remarkable regenerative capacity when metabolic stress is reduced. But we must start earlier, think more holistically, and emphasize the gut-liver connection in both prevention and treatment.

A gut-first strategy for the future

To combat the rise of fatty liver disease in younger populations, we need a new approach—one rooted in prevention, education, and microbiome science. Here’s where we can start:

• Integrate screening into routine primary care visits, particularly for patients with metabolic risk factors—even if they’re young or non-obese.
• Shift the focus from calorie counting to food quality. Diets rich in fiber, fermented foods, and whole ingredients support microbial health, reduce inflammation, and can improve liver function.
• Promote public awareness around the gut-liver axis—educating both patients and clinicians that the health of one directly affects the other.
• Support research and innovation into microbiome-targeted therapies, including prebiotics, probiotics, and dietary interventions tailored to microbial composition.

Conclusion

Fatty liver disease is no longer a distant threat confined to older adults with longstanding metabolic issues. It’s here, it’s rising, and it’s affecting the next generation of patients—often silently.

But this isn’t a hopeless narrative. With earlier recognition and a renewed focus on nutrition and gut health, we have the tools to intervene before irreversible damage sets in.

If we’re going to take MASH seriously, we need to look beyond the liver—and start with the gut.

Anuj Vikrant Sharma is a board-certified gastroenterologist and section chief at PeaceHealth Medical Group in Longview, Washington. He also serves as a clinical assistant professor at Washington State University. With over a decade of experience in digestive health and advanced endoscopy, Dr. Sharma is committed to delivering evidence-based, patient-centered care. He has led numerous quality improvement initiatives and actively mentors medical trainees. Known for his collaborative approach and dedication to clinical excellence, Dr. Sharma continues to be a trusted leader in his field.