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A surprising new study from the University of Michigan has revealed that non-alcoholic fatty liver disease (NAFLD)may significantly increase the risk of heart disease—even in people with a normal body mass index (BMI).
Traditionally, NAFLD has been associated with individuals who are overweight or obese, but this research highlights that lean individuals with NAFLD may face even greater cardiovascular risks than those who are overweight.
What is NAFLD?
NAFLD is a condition where excess fat builds up in the liver, despite little or no alcohol consumption. It is one of the most common liver diseases worldwide and can lead to serious complications, including:
Cirrhosis (scarring of the liver)
Type 2 diabetes
Heart disease
Kidney disease
While NAFLD is more frequently seen in overweight individuals, it can also occur in people with a normal BMI, and until now, little research has been done on how it affects this group.
Study Findings: Higher Heart Disease Risk in Lean Patients
Researchers analyzed more than 10,000 adults diagnosed with NAFLD at the University of Michigan Hospital between 2012 and 2021. They divided patients into four BMI categories:
Lean (BMI: 18.5–24.9)
Overweight (BMI: 25–29.9)
Class 1 obesity (BMI: 30–34.9)
Class 2–3 obesity (BMI: 35–40)
Unexpectedly, the study found that lean patients with NAFLD had a higher risk of developing heart disease than non-lean patients. Specifically, lean individuals with NAFLD had a greater prevalence of peripheral vascular disease, brain-vascular disease, and heart disease compared to their overweight and obese counterparts.
Why Are Lean Individuals More at Risk?
Researchers had assumed that people with a normal BMI would have a lower risk of metabolic and cardiovascular conditions. However, the study’s results suggest that having a normal BMI does not necessarily mean a person is metabolically healthy—especially if they have NAFLD.
The exact reasons behind the increased heart disease risk in lean NAFLD patients remain unclear. Some possible explanations include:
Genetic factors that make some lean individuals more susceptible to metabolic diseases.
Differences in fat distribution, as some lean individuals may store excess fat around their organs rather than under the skin.
Inflammation linked to NAFLD that may contribute to heart disease.
Because the cause of this link is still unknown, researchers stress the importance of not overlooking NAFLD in lean patients. These individuals may still face serious health risks and should receive the same level of monitoring and treatment as those who are overweight.
Preventing Heart Disease if You Have NAFLD
If you have NAFLD, taking steps to protect your heart health is crucial, regardless of your BMI. Here are some key ways to reduce your risk:
Follow a heart-healthy diet: Eat plenty of fruits, vegetables, whole grains, lean protein, and healthy fats while avoiding processed foods, added sugars, and unhealthy fats.
Exercise regularly: Aim for at least 30 minutes of moderate exercise (such as walking, cycling, or swimming) most days of the week.
Maintain healthy blood pressure and cholesterol levels: Work with your doctor to monitor and manage these risk factors.
Quit smoking: Smoking significantly increases the risk of heart disease. If you smoke, seek support to quit.
Manage other health conditions: If you have diabetes or high blood pressure, keeping them under control can lower your heart disease risk.
Get regular check-ups: Routine medical visits can help detect and manage potential health issues early.
Future Research
The University of Michigan team plans to conduct long-term studies to determine whether lean NAFLD patients are at an even greater risk of developing cardiovascular disease over time. Understanding why lean individuals are affected differently could lead to better prevention and treatment strategies.
Takeaway
This study challenges the traditional belief that heart disease risk is mainly tied to obesity. It highlights that even individuals with a normal BMI can be at high risk if they have NAFLD. Since heart disease is the leading cause of death worldwide, it’s essential for both doctors and patients to be aware of this hidden risk.
Regardless of body weight, taking care of liver and heart health should be a priority—and lean individuals should not assume they are safe from metabolic diseases. Ongoing research will help uncover more about this unexpected connection and improve treatment options for those at risk.
If you care about heart disease, please read studies that herbal supplements could harm your heart rhythm, and how eating eggs can help reduce heart disease risk.
For more health information, please see recent studies that apple juice could benefit your heart health, and results showing yogurt may help lower the death risks in heart disease.
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