Key Numbers from the Guidance

25–30%
Estimated adult NAFLD prevalence ref 1
(general population)
<1.3
FIB-4 cutoff to exclude advanced fibrosis ref 18
(primary screening)
>10%
Weight loss needed to improve fibrosis ref 35
(3–5% improves steatosis)
80%
NASH resolution after bariatric surgery ref 41
(at 1 year, maintained at 5 years)

This 2023 AASLD practice guidance is one of the most comprehensive documents on fatty liver disease (NAFLD) available, covering everything from who should be screened, to which tests matter most, to what treatments can help. It replaced the previous 2018 guidance and reflects major advances in non-invasive testing and understanding of disease progression. ref 1

NAFLD vs MASLD — a note on nomenclature
This guidance uses the term "NAFLD" (nonalcoholic fatty liver disease). In 2023, an international consensus renamed the condition "MASLD" (metabolic dysfunction–associated steatotic liver disease). The disease criteria are essentially the same. Newer AASLD guidelines use the MASLD terminology, but the clinical content of this guidance remains current.

What Is NAFLD?

NAFLD means that at least 5% of your liver cells contain fat (macrovesicular steatosis), and this is not explained by other causes like heavy alcohol use or certain medications. ref 10 It includes a spectrum of disease: simple fatty liver (NAFL), which may have mild inflammation; NASH, where inflammation and cell injury (ballooning) are present and can lead to scarring; and ultimately cirrhosis.

NAFLD affects an estimated 25–30% of adults globally. ref 1 NASH was found in 14% of asymptomatic patients undergoing routine colon cancer screening. ref 2 NASH-related cirrhosis is already the leading reason for liver transplantation in women and people over 65. ref 3

How Does the Disease Progress?

Fibrosis (scarring) is the key factor that determines outcomes. In patients with NASH, fibrosis progresses roughly one stage every 7 years, compared with one stage every 14 years in patients with simple fatty liver (NAFL). ref 4 Among those who develop cirrhosis, decompensation occurs at a rate of 3–20% per year. ref 5

For patients with NAFLD overall, the most common causes of death are cardiovascular disease and non-liver cancers, followed by liver disease. ref 6 In a study of 1,773 patients, all-cause mortality was dramatically higher with more advanced fibrosis: 0.32 per 100 person-years for stages F0–F2, compared with 0.89 for bridging fibrosis (F3) and 1.76 for cirrhosis. ref 7 The encouraging news: cirrhosis regression in clinical trials has been associated with a 6-fold reduction in liver-related events. ref 68

Patients with NASH and at least stage 2 fibrosis — called "at-risk" NASH — face a demonstrably higher risk of liver-related morbidity and mortality and are the focus of treatment efforts. ref 8

Who Should Be Screened for Fibrosis?

AASLD does not recommend screening everyone in the general population for NAFLD. ref 15 Instead, they recommend targeted screening in high-risk groups.

Individuals who should be screened for advanced fibrosis include those with type 2 diabetes, medically complicated obesity, a family history of cirrhosis, or more than mild alcohol consumption. ref 17 T2DM is the single most impactful risk factor — patients with T2DM have a NAFLD prevalence of 30–75% and a higher risk of progressing to NASH with fibrosis. ref 11 ref 12 Screening in T2DM patients is considered cost-effective. ref 73

Family history matters too: first-degree relatives of patients with NASH cirrhosis have a 12-fold higher risk of advanced fibrosis. ref 34 NAFLD itself is associated with a 2- to 5-fold risk of developing diabetes. ref 13

The Screening Pathway: FIB-4 First

AASLD recommends starting with FIB-4 — a simple, no-cost calculation based on your age, ALT, AST, and platelet count. ref 16

If your FIB-4 is below 1.3, advanced fibrosis is unlikely, and you can be followed in primary care. ref 18 If your FIB-4 is above 2.67, the risk of advanced fibrosis is high and specialist referral is recommended. ref 19 For patients over 65, a higher FIB-4 cutoff of >2.0 should be used. FIB-4 has low accuracy in those under 35, so secondary assessment is recommended for younger patients with risk factors. ref 74

If FIB-4 is ≥1.3, a secondary test is recommended — preferably FibroScan (VCTE) or >ELF test to further evaluate fibrosis severity. ref 21

For patients with T2DM, prediabetes, or ≥2 metabolic risk factors, FIB-4 should be repeated every 1–2 years. ref 20

LiverDecoded Calculator Connection
Use our 9-Score Calculator to compute your FIB-4, APRI, NAFLD Fibrosis Score, and other scores from a single set of lab values. A FIB-4 below 1.3 is reassuring. ref 18 If your score is ≥1.3, this guidance recommends a second test like FibroScan or ELF. ref 21

Non-Invasive Test (NIT) Thresholds

AASLD provides detailed thresholds for multiple non-invasive tests. The following table summarizes the key cut points for detecting advanced fibrosis and cirrhosis.

Advanced Fibrosis Detection

TestAdvanced Fibrosis LikelyAdvanced Fibrosis Unlikely
FIB-4 ≥ 2.67 ref 19 < 1.3 ref 18
FibroScan (VCTE) ≥ 12 kPa ref 22 < 8 kPa ref 22
ELF Score ≥ 9.8 ref 26 < 7.7
MRE ≥ 3.63 kPa ref 25 < 2.55 kPa

Cirrhosis Detection

TestCirrhosis Likely (Rule-In)Cirrhosis Unlikely (Rule-Out)
FibroScan (VCTE) ≥ 20 kPa ref 23 < 8 kPa
MRE ≥ 5 kPa ref 25 < 3 kPa
ELF Score ≥ 11.3 ref 27 < 7.7
FIB-4 ≥ 3.48 ref 23 < 1.67

MRE is the most accurate imaging-based test for fibrosis in NAFLD, and is more sensitive than VCTE for detecting fibrosis stage ≥2. ref 24 However, it is more expensive and requires a radiology suite. MRE liver stiffness stratified at <5, 5–8, and >8 kPa was associated with 1.6%, 17%, and 19% risk of decompensation over 3 years. ref 70

Identifying Steatosis

Standard ultrasound is not recommended for detecting fatty liver due to low sensitivity, especially with milder steatosis or obesity. ref 64 CAP (≥288 dB/min) provides a point-of-care assessment of steatosis. ref 28 MRI-PDFF (≥5%) is the most sensitive and accurate method for measuring liver fat. ref 29

Emerging "At-Risk" NASH Scores

Several newer composite tests aim to identify "at-risk" NASH (NASH with ≥F2 fibrosis). The FAST score (combining FibroScan stiffness, CAP, and AST) uses a cutoff of ≥0.67 to rule in (90% specificity) and <0.35 to rule out. ref 62 The MEFIB index (FIB-4 ≥1.6 plus MRE ≥3.3 kPa) has >90% positive predictive value and a 99% negative predictive value for 5-year decompensation risk. ref 63

When is a liver biopsy needed?
Liver biopsy remains the reference standard for grading and staging NASH ref 65, but AASLD recommends it only in specific situations: when non-invasive tests are discordant or indeterminate, when there is diagnostic uncertainty or a competing diagnosis, or when liver enzymes remain persistently elevated for more than 6 months. ref 66

Initial Evaluation and Comorbidities

When NAFLD is suspected, your doctor should assess metabolic comorbidities, quantify alcohol intake, and rule out other liver diseases. An important nuance: ALT levels are frequently normal in patients with advanced NASH liver disease. ref 61 True normal ALT is 29–33 U/L in men and 19–25 U/L in women — lower than what most laboratories report as the upper limit. ref 9 As a general rule, ALT above 30 U/L should be considered abnormal. ref 67

Key Comorbidities

Type 2 diabetes is the most impactful risk factor for NAFLD development, fibrosis progression, and liver cancer. ref 11 NAFLD prevalence in T2DM ranges from 30% to 75%. ref 12 NAFLD itself is also associated with a 2-fold increased prevalence of chronic kidney disease. ref 59 Patients who are overweight or obese with NAFLD should be screened for obstructive sleep apnea. ref 69

Statins are safe and recommended for cardiovascular risk reduction across all stages of NAFLD, including compensated cirrhosis. ref 14

Alcohol and NAFLD
Patients with clinically significant fibrosis (stage F2 or higher) should abstain from alcohol completely. ref 32 Even moderate alcohol use increases the probability of advanced fibrosis, especially in patients with obesity or diabetes. ref 33
Cirrhosis requires active surveillance
Patients with NASH cirrhosis need biannual HCC screening, variceal screening, and ongoing monitoring for signs of decompensation. ref 31 An ELF score ≥11.3 is associated with increased decompensation risk and should prompt these screenings. ref 27

Lifestyle Treatment: The Foundation

A healthy diet and regular exercise form the foundation of NAFLD treatment for virtually all patients. Even if weight loss is not needed, improved diet and exercise promote cardiovascular health along with liver health.

Weight Loss Targets

Even modest weight loss helps: 3–5% reduces liver fat (steatosis). But greater than 10% weight loss is generally required to improve NASH and fibrosis. ref 35 Unfortunately, achieving this is difficult — fewer than 10% of patients sustain effective weight loss at 1 year despite structured programs, and fewer than half maintain it at 5 years. ref 36

Diet

AASLD recommends a caloric deficit diet for overweight patients, with limited carbohydrates and saturated fat and enriched with fiber and unsaturated fats. The Mediterranean diet is specifically recommended due to its cardiovascular and liver fat benefits. ref 37 Excessive fructose consumption — from sugar-sweetened beverages and processed foods — independently increases the risk of NAFLD, NASH, and fibrosis. ref 60

Coffee consumption (caffeinated or decaffeinated) of 3 or more cups daily is associated with less advanced liver disease and can be recommended in the absence of contraindications. ref 38

Exercise

Exercise benefits the liver and cardiovascular system independently of weight loss. ref 40 Regular moderate exercise at least 5 times per week, totaling 150 minutes per week, or increasing activity by more than 60 minutes per week, can prevent or improve NAFLD. ref 39

Bariatric Surgery

For patients meeting criteria (BMI ≥40, or BMI ≥35 with comorbidities), bariatric surgery can be highly effective. NAFLD/NASH is increasingly accepted as a qualifying comorbidity. ref 42 In a prospective study, NASH resolved in 80% of patients by one year, and this was maintained at five years. ref 41

Bariatric surgery and cirrhosis
Decompensated cirrhosis or clinically significant portal hypertension is a contraindication for bariatric surgery due to increased mortality risk. ref 43 Compensated cirrhosis requires careful evaluation by a multidisciplinary team.

Available Medications

See 2024 and 2025 AASLD updates for newer treatment options
As of March 2026, US FDA has approved Resmetirom and Semaglutide for treatment of MASH/NASH fibrosis and consequently AASLD has published updates to this original guidance recommending these as treatment options. Look at AASLD Resmetirom for MASH (Oct 2024) and AASLD Semaglutide for MASH (Nov 2025) for more information.

At the time of this 2023 guidance, no drugs were FDA-approved for NASH. ref 44 However, certain medications approved for related conditions may benefit the liver.

Vitamin E (800 IU daily)

In the PIVENS trial, natural vitamin E (800 IU/day for 96 weeks) improved NASH histology compared with placebo. ref 45 AASLD suggests it can be considered in select individuals with NASH who do not have diabetes. ref 51 In patients with advanced fibrosis, vitamin E use was associated with lower decompensation rates (37% vs 62%) and higher transplant-free survival (78% vs 49%). ref 46

Pioglitazone (30–45 mg daily)

Pioglitazone improves NASH histology and insulin resistance in patients with or without T2DM. ref 47 AASLD recommends it can be considered in the context of T2DM. ref 50 Side effects include weight gain, osteoporosis in postmenopausal women, a debated bladder cancer risk, and possible worsening of heart failure. ref 71

Semaglutide and GLP-1 Receptor Agonists

In a phase 2b trial, daily semaglutide achieved NASH resolution in 59% vs 17% placebo. ref 48 AASLD says semaglutide can be considered for its approved T2DM/obesity indications in patients with NASH, as it confers cardiovascular benefit and improves NASH. ref 49

Important limitation of current therapies
AASLD notes that available data (when this guideline was published) on pioglitazone, and vitamin E do not demonstrate a direct antifibrotic benefit, and none has been carefully studied in cirrhosis. ref 52. As of March 2026, US FDA has approved Resmetirom and Semaglutide for treatment of MASH/NASH fibrosis and consequently AASLD has published updates to this original guidance recommending these as treatment options. Look at AASLD Resmetirom for MASH (Oct 2024) and AASLD Semaglutide for MASH (Nov 2025) for more information.

Medications That Do NOT Help NASH

Metformin, ursodeoxycholic acid (UDCA), DPP-4 inhibitors, statins, and silymarin (milk thistle) have all been well studied and should not be used as treatments for NASH, as they do not offer meaningful histological improvement. ref 53 Statins remain important for cardiovascular risk reduction but do not treat the liver disease itself. ref 14

How to Track Treatment Response

Improvement in ALT or reduction in liver fat on imaging can be used as surrogates for histological improvement. ref 56 ALT normalization is predictive of NASH resolution in response to both lifestyle changes and drug therapy. ref 72

An ALT reduction of ≥17 IU/L has been associated with histological improvement. ref 54 A ≥30% decline in MRI-PDFF (liver fat) is associated with a 5-fold improvement in odds of NASH resolution. ref 55

An increase in liver stiffness of ≥20% on either FibroScan (VCTE) or MRE may signal disease progression and worsening long-term outcomes. ref 30

Track your progress on LiverDecoded
Upload your lab reports to the LiverDecoded Dashboard to visualize ALT, FibroScan, and other values over time. An ALT drop of ≥17 IU/L is a positive sign. ref 54
Calculator
FIB-4 Score Calculator
Calculate your fibrosis risk score from standard lab values
Topic
FibroScan (VCTE) Results Explained
What your liver stiffness kPa score means for fibrosis staging
Condition
MASLD / Fatty Liver / MASH / Hepatic Steatosis Overview
Screening, diagnosis, staging, and treatment pathways
Guideline
AASLD MASLD Nomenclature Update (2023): What NAFLD to MASLD Means for Patients
2023 AASLD update renaming NAFLD to MASLD and NASH to MASH. Covers new definitions, CMRF criteria, the SLD classification system, and the evaluation algorithm
Guideline
AASLD Semaglutide for MASH (Nov 2025 Update)
Who qualifies for Wegovy under the MASLD/MASH nomenclature
Guideline
AASLD Resmetirom Guidance (Oct 2024 Update)
The other FDA-approved MASH treatment

Frequently Asked Questions

NAFLD means at least 5% of liver cells contain fat, in the absence of other causes like alcohol or medications. ref 10 It affects an estimated 25–30% of adults worldwide. ref 1 The spectrum ranges from simple fatty liver (NAFL) to NASH, which includes inflammation and cell damage, and can progress to cirrhosis.
AASLD recommends screening for advanced fibrosis in high-risk groups: people with type 2 diabetes, medically complicated obesity, family history of cirrhosis, or more than mild alcohol consumption. ref 17 T2DM is the strongest risk factor for NAFLD progression, with 30–75% prevalence. ref 12 General population screening is not recommended. ref 15
FIB-4 is a simple calculation using your age, ALT, AST, and platelet count. A FIB-4 below 1.3 means advanced fibrosis is unlikely. ref 18 A FIB-4 above 2.67 signals high risk. ref 19 If you are over 65, a higher cutoff of 2.0 is used. ref 19 FIB-4 has low accuracy in those under 35. ref 74
A FibroScan (VCTE) liver stiffness below 8 kPa helps rule out advanced fibrosis. Values between 8 and 12 kPa may indicate fibrotic NASH. Above 12 kPa suggests a high likelihood of advanced fibrosis, and above 20 kPa raises concern for cirrhosis. ref 22 ref 23
If you have type 2 diabetes, prediabetes, or two or more metabolic risk factors, AASLD recommends repeating FIB-4 every 1–2 years. ref 20 If you have fewer risk factors and no diabetes, reassessment every 2–3 years may be sufficient.
Yes. ALT levels are frequently normal in patients with advanced liver disease from NASH. ref 61 True normal ALT is 29–33 U/L for men and 19–25 U/L for women — lower than most lab reference ranges report. ref 9 ALT above 30 U/L should be considered abnormal. ref 67
As little as 3–5% weight loss can reduce liver fat (steatosis). To improve inflammation and fibrosis, greater than 10% weight loss is generally needed. ref 35 However, fewer than 10% of patients achieve and sustain this through lifestyle alone. ref 36
At the time of this 2023 guidance, no drugs were FDA-approved specifically for NASH. ref 44 However, vitamin E (for non-diabetic NASH) ref 51, pioglitazone (for NASH with T2DM) ref 50, and semaglutide (for its obesity/T2DM indications) ref 49 may benefit the liver. Note: semaglutide has since received FDA approval for MASH in August 2025.
No. AASLD states that metformin does not improve NASH histology and should not be used as a treatment for NASH. ref 53 However, metformin may still be appropriate for managing type 2 diabetes.
Yes. NAFLD in lean individuals (BMI <25) occurs in about 4.1% of people in the US and up to 19% in Asia. ref 57 Lean patients with NAFLD still tend to have increased insulin resistance, visceral fat, and decreased muscle mass compared to healthy controls. ref 58
If you have clinically significant fibrosis (stage 2 or higher), AASLD recommends complete abstinence from alcohol. ref 32 Even moderate drinking increases fibrosis risk, particularly if you also have obesity or diabetes. ref 33