Baffled by NAFLD? The Facts About Fatty Liver
A webinar summary moderated by Janie Yang, MD, paneled by Jennifer Leong, MD, and Suzie Finkel, MS, RD, CDN
This metabolic condition can lead to cirrhosis and is linked with an increased risk of cardiovascular disease, extra-hepatic malignancies, and chronic kidney disease. In this blog post, we will explore the pathogenesis, diagnosis, and treatment of NAFLD, as well as the importance of screening highrisk groups.
NAFLD is becoming increasingly prevalent in both the adult and pediatric populations worldwide; it is estimated that 25-30% of US adults and 25% of the global population are affected. This condition can cause a range of liver consequences, including cirrhosis, and is also linked to an increased risk of cardiovascular disease, extra-hepatic malignancies, and chronic kidney disease.
The Pathogenesis of NAFLD
Though the natural history of NAFLD is still not fully understood, the spectrum of the condition is divided into different stages. NAFFL, or fat deposition in the liver without inflammation or scarring, is the first stage. About 40% of this group can progress to non-alcoholic steatohepatitis (NASH), which is characterized by inflammation and cellular injury. As the disease continues, fibrosis or scarring can occur, and eventually lead to NASH cirrhosis and liver failure.
The disease is further complicated by comorbidities such as obesity, metabolic syndrome, and type 2 diabetes, which can both drive NASH progression and be made worse by NAFLD. Nutrition, behavior, and genetics may also play a role in the development of the condition. Exercise and coffee have been found to have protective effects, while alcohol and high cholesterol can worsen it.
Though the prognosis of NAFLD varies depending on the severity of the condition, it is important to understand the risks and available treatments in order to manage it properly., While FLD typically occurs in people with a BMI of 30 or higher, it can also be seen in people with a BMI below 25, even as low as 23 for Asians. In the U.S., it accounts for 7% of fatty liver cases and can range as high as 19-30% in Asia. Patients with lean fatty liver may demonstrate less hepatic steatosis, but there is still controversy on outcomes for them versus those with higher BMI.
Signs & Symptoms
Most often, patients are asymptomatic, though some may experience right upper side abdominal discomfort. Fatty liver is sometimes discovered during routine physical exams when elevated liver enzymes are found, though up to 50% of people with fatty liver may have normal liver enzymes.
Other signs include an enlarged liver on exam or imaging studies, fatigue in the legs, jaundice or ecteric (eyes/skin yellowing), diffuse itching, and swelling.
FLD is usually diagnosed by exclusion of other potential conditions, such as alcohol, medications, and other liver diseases. Blood tests, imaging studies such as ultrasound, CT scan, MRI and noninvasive scans such as FibroScan and Velicure scan, which measure fat and scarring, are used to make a diagnosis. Liver biopsy is the only way to identify inflammation.
Currently, there are no FDA-approved medications to treat FLD and the cornerstone of therapy is lifestyle modification, including weight loss, healthy eating habits, an active lifestyle, managing comorbid conditions such as diabetes, high cholesterol, and hypertension, abstaining from smoking, and minimizing/avoiding alcohol. Studies have shown that 5-10% total body weight loss can result in a reduction of liver enzymes, triglycerides, A1C, and risk of type 2 diabetes, as well as resolution of fat in the liver and inflammation. Exercise is also beneficial, with 150-300 minutes of moderate physical activity per week associated with health benefits and a lower risk of all-cause mortality.
Research has shown that regular exercise and healthy diet modifications can improve metabolic disease, even without weight loss. A meta-analysis of 316 people with NAFLD found that people engaging in regular exercise had improved liver enzymes, LDL cholesterol, and triglycerides, despite not experiencing weight loss. Additionally, a study of 18,000 people with NAFLD showed that people with normal BMI were more likely to develop metabolic syndrome than those with higher BMI.
The reality is that individuals of all body sizes can be affected by metabolic conditions, and focusing on behavior changes instead of body weight can lead to better health outcomes. Weight loss might accompany helpful dietary change, but it is not a direct control behavior and it is not guaranteed for everyone.
Healthcare providers must be mindful of this and focus on health-promoting behaviors instead of the number on the scale. Adopting extreme diets with too much animal protein and no healthy carbohydrates, as well as long fasting periods, can negatively impact metabolic health. Patients who focus on weight loss alone may abandon healthy changes if they don’t experience the desired outcome, and this can result in weight cycling and disordered eating.
In summary, weight and metabolic health are not the same thing, and behavior changes are what have the biggest impact on metabolic outcomes., Fortunately, there are treatments and lifestyle modifications that can help manage the condition. Diet and meal patterns have been shown to significantly improve several aspects of FLD, and this article will discuss how to make dietary changes to benefit the condition.
Circadian Aligned Eating
Circadian aligned eating is a dietary approach that involves “front-loading” overall food intake and carbs to better align with metabolism. This means having a healthy breakfast and avoiding skipping meals. Eating most of your energy at night should be avoided, and eating the same amount of food throughout the day is recommended.
We often refer to an anti-inflammatory diet to benefit FLD, known as a Mediterranean-style diet. This diet includes eating more fiber-rich carbohydrates, plant-based foods, non-starchy vegetables and fruits, and whole grains, and avoiding red meat and high-fat dairy products. Eating foods high in unsaturated fats, like fish and avocado, and reducing sugary foods can also be beneficial.
Coffee and Alcohol
Coffee drinking has been shown to have a protective benefit against the progression of FLD, but be aware that significant alcohol consumption can accelerate liver injury and fibrosis progression—it should be avoided completely if there is significant fibrosis or cirrhosis. For those without fibrosis, there is no defined amount of alcohol considered safe, and decisions should be made on an individual basis., Diagnosis and early management is important for preventing and even reversing liver damage. Diet and exercise are the cornerstone of prevention and treatment. Non-invasive alternatives to liver biopsy are available for diagnosis.
Vitamins, Medications, and Bariatric Surgery
Vitamins and medications, such as Pyoglitazone, which is approved for patients with Type 2 diabetes, have been shown to have some benefit in reducing fibrosis, inflammation, and steatosis.
However, these treatments are accompanied by potential side-effects such as weight gain, heart failure, and fractures. The GLP-1 agonists class of medications are used to treat Type 2 diabetes and weight management, and have shown potential in reducing steatosis and fibrosis, although they are currently not approved for use in NAFLD/NASH treatment. Bariatric surgery has been found to be beneficial, and can resolve NASH, improve fibrosis, and induce sustained weight loss.
Screening for High-Risk Groups
Universal screening is not yet recommended, but high-risk groups (those with Type 2 diabetes, a BMI of 30 or more, two or more cardiometabolic risk factors, or signs of insulin resistance) should be screened.
In conclusion, NAFLD is a serious condition with serious consequences for the liver. Early diagnosis and management are key for preventing and reversing damage. Diet and exercise are the main treatment strategies, and there are additional treatments available for those who qualify. Screening is recommended for high-risk groups.