The truth you need to know about fatty liver

Introduction

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), is a common liver condition characterized by excessive fat buildup in liver cells, unrelated to heavy alcohol use. This disease affects millions worldwide and involves metabolic factors that disrupt normal liver function. Research shows that obesity, diabetes, and lifestyle play key roles in its development.

What Is MASLD?

MASLD occurs when fat accumulates in the liver due to metabolic imbalances, leading to potential inflammation and damage. Normally, the liver contains minimal fat, but in MASLD, more than 5% of its weight can be fat, a condition called steatosis. It is classified as a metabolic disorder, where the body's energy processing goes awry, causing fat to deposit in the liver instead of being used or stored elsewhere. If untreated, it can progress to more severe forms, increasing the risk of liver failure.

Types of MASLD

MASLD encompasses several stages, each with varying severity. Simple steatosis (fatty liver) is the most common, involving fat buildup without inflammation, affecting the majority of cases. The more advanced form is metabolic dysfunction-associated steatohepatitis (MASH, formerly NASH), which includes liver inflammation and cell damage, accounting for about 20-30% of MASLD cases. Other related conditions include MASLD with fibrosis (scarring) and cirrhosis, where extensive scarring impairs liver function. It is possible for the disease to evolve from one stage to another over time.

Causes

The exact causes of MASLD are multifaceted, involving genetic, metabolic, and environmental factors. Obesity and insulin resistance are primary drivers, as excess body fat leads to fat spillover into the liver. Triggers may include type 2 diabetes, high cholesterol, poor diet, sedentary lifestyle, or certain medications, which exacerbate fat accumulation and inflammation. Genetic predisposition is evident, as the condition often clusters in families, and rapid weight loss can paradoxically worsen it in some cases.

Symptoms

Symptoms of MASLD vary by stage and severity but are often absent in early phases, making it a "silent" disease. Common signs include fatigue, weakness, and discomfort in the upper right abdomen. In advanced stages like MASH or cirrhosis, symptoms may escalate to jaundice (yellowing of skin and eyes), itching, abdominal swelling, leg edema, or mental confusion. The disease can cycle through periods of stability and worsening, influenced by lifestyle factors.

Is MASLD Contagious?

MASLD is not contagious and cannot be spread through physical contact, shared items, or environmental exposure. As a metabolic disorder, it arises from internal factors like genetics and lifestyle, rather than external pathogens such as viruses or bacteria. Misunderstandings about its transmissibility often stem from its association with obesity, but it is driven by personal health conditions, not interpersonal transmission.

Prevalence

MASLD affects approximately 30-38% of the global adult population, （ https://pmc.ncbi.nlm.nih.gov/articles/PMC10026948/ ）with higher rates in regions with rising obesity. In the United States, estimates indicate about 25-34% of adults (around 100 million people) live with MASLD as of 2025,( https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2829360 ) with projections rising to 41% by 2050 due to increasing metabolic disorders. It impacts both genders similarly, with variations by ethnicity (higher in Hispanic Americans) and age, often starting in adulthood but increasingly seen in children amid obesity trends. MASH affects 5-7% of US adults.( https://diabetesjournals.org/care/article/48/7/1057/160536/Metabolic-Dysfunction-Associated-Steatotic-Liver )

Conclusion

MASLD represents a multifaceted liver condition influenced by metabolic, genetic, and lifestyle elements. Awareness of its types, causes, symptoms, and prevalence contributes to management and prevention. Ongoing research continues to explore treatments and impacts, emphasizing early intervention.