You look healthy but have fatty liver? Here's why even lean people can develop MASLD

One of the most common conversations in the clinic today starts with surprise. A person comes in for a routine health check, feeling perfectly well, only to be told that the ultrasound shows a “fatty liver”.

The first response is often, “But doctor, I hardly drink.” The second common response is, “My liver tests are normal, so is this really something I need to worry about?” Both questions reflect how we have traditionally understood liver disease and why we now need to look at it differently.

Fatty liver is no longer viewed simply as a problem related to alcohol. Increasingly, it is linked to the same metabolic changes we see with obesity, diabetes, high cholesterol and high blood pressure. The condition is now called metabolic dysfunction-associated steatotic liver disease, or MASLD, previously known as non-alcoholic fatty liver disease or MAFLD.

This is not a rare finding. A systematic review of Indian studies estimated NAFLD in about 38.6 per cent of adults studied, that is, close to 4 out of 10 Indians. In other words, the person sitting next to you at work, the relative or friend who looks reasonably fit, or someone who has never considered themselves 'unhealthy' may still be carrying excess fat in the liver.

The connection with obesity is especially important. When the body has more energy than it can use, particularly in the presence of insulin resistance, fat does not remain confined to the places we can see; it can begin accumulating around internal organs and inside the liver as well. A large meta-analysis involving more than 100,000 people found MAFLD in about 70 per cent of people who were overweight and about 75 per cent of those living with obesity.

Obesity remains an important risk factor for fatty liver disease, but BMI alone does not capture every person at risk. Fatty liver disease can also occur in individuals who are not living with obesity and may have a normal BMI. This lean or non-obese phenotype can still be associated with fatty liver and metabolic risk factors that are not captured by BMI alone.

Globally, a systematic review and meta-analysis estimated that about 40 per cent of people with MAFLD didn’t have obesity and nearly one in five were lean. This is why waist circumference, blood sugar, triglycerides and overall metabolic health should be considered alongside body weight and BMI. Why are liver and obesity specialists concerned? Because fatty liver often makes no noise while it is developing.

Most people have no obvious symptoms in the early stages and the condition is frequently detected during investigations done for another reason. Even normal liver enzyme results do not always mean that the liver is healthy. Research has shown that some people with fatty liver disease can have normal liver enzyme levels despite having significant liver scarring.

For many, fat in the liver may remain relatively stable. But in some people, it is accompanied by inflammation and injury to liver cells. This more serious form, now called metabolic dysfunction-associated steatohepatitis or MASH, can gradually lead to fibrosis, essentially scarring of the liver. Progressive fibrosis can eventually lead to cirrhosis, liver failure and hepatocellular carcinoma in some patients.

But MASH is not only a liver condition. It is closely linked with cardiovascular disease, which is a major cause of illness and death among people with MASH. MASH can also be associated with other health problems beyond the liver, including type 2 diabetes and chronic kidney disease. This is why fatty liver should not be looked at in isolation; it can be a sign of a wider metabolic problem affecting the body.

So, who should be particularly alert? People living with obesity or an increasing waistline, those with prediabetes or type 2 diabetes, high blood pressure, high triglycerides, or abnormal cholesterol deserve closer attention. Depending on individual risk, doctors may use blood-based scores such as FIB-4, followed, where appropriate, by tests such as liver elastography to assess the likelihood of significant fibrosis.[5] Not everyone needs every test, but the finding should not simply be filed away as 'mild fatty liver' and forgotten.

The encouraging part is that the management of MASH has evolved significantly in recent years. Lifestyle modification and management of associated cardiometabolic risk factors remain part of current clinical guidance. Evidence has also shown that substantial weight loss can improve MASH and liver fibrosis. At the same time, medical management has become an increasingly important part of the treatment landscape, with newer treatments demonstrating improvements in both MASH and liver fibrosis.

The answer is therefore neither panic nor neglect. It is recognising that fatty liver is a metabolic warning sign long before it becomes a liver emergency. The report may say 'fatty liver', but what it is really asking us to examine is our waistline, our blood sugar, our sleep, our food habits, our activity levels, and the metabolic health we often take for granted. Fatty liver is common, often silent, and frequently dismissed. Proactive screening gives us time to act.

(The author is a senior consultant in endocrinology and metabolism at Apollo Hospitals, Bhubaneswar)

The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK.