Baseline Hepatic Steatosis
Fat has quietly accumulated inside liver cells for years.
- 32%: Global MASLD prevalence (of adults worldwide)
- >5.5%: Diagnostic fat threshold (intrahepatic triglyceride)
- ~20%: Progression to MASH (of steatosis cases)
- 18.4%: Baseline fat (this sim) (starting value)
What is hepatic steatosis
Triglycerides build up inside hepatocytes, past 5% of liver weight.
Steatosis alone is often silent — no symptoms, no pain.
Why fat accumulates
Insulin resistance drives fat delivery, lipogenesis, and poor fat export.
Risk of silent progression
Untreated steatosis can advance toward inflammation and fibrosis over years.
Treatment Initiated
Two different drug classes attack liver fat from separate angles.
- GLP-1 RA: Semaglutide class (incretin agonist)
- TZD: Pioglitazone class (PPAR-gamma agonist)
- 2.4 mg: Typical sema dose (weekly, subcutaneous)
- 30-45 mg: Typical pio dose (daily, oral)
Semaglutide mechanism
Mimics GLP-1, suppresses appetite, slows gastric emptying.
Weight loss is the dominant driver of fat reduction here.
Pioglitazone mechanism
Activates PPAR-gamma, boosts adipose and hepatic insulin sensitivity.
Choosing a regimen
Dose and drug choice set the pace of fat clearance.
Weight & Insulin Sensitivity Improve
Systemic metabolism changes before the liver visibly clears fat.
- ~15%: STEP trial weight loss (semaglutide, 68 wk)
- ~30%: Pioglitazone HOMA-IR drop (insulin resistance index)
- 2-8: Onset of metabolic change (weeks typical)
- up to 47: Insulin sensitivity gain (index points, this sim)
Weight loss trajectory
Semaglutide weight loss front-loads early, then plateaus by week 52.
Insulin sensitivity trajectory
Pioglitazone raises sensitivity steadily and linearly across the year.
Both mechanisms converge on the same downstream target: liver fat.
Why order matters
Metabolic improvement always precedes measurable hepatic fat decline.
Liver Fat Reduction
Intrahepatic triglyceride content falls week over week.
- ~66%: Sema fat reduction (72wk) (relative, high dose)
- ~52%: Pio fat reduction (52wk) (relative, steady rate)
- gold standard: MRI-PDFF (fat quantification method)
- <5.5%: Resolution threshold (intrahepatic fat)
Semaglutide fat kinetics
Fast early decline, tracking rapid weight loss curves.
Faster starters, but pioglitazone often closes the gap by week 52.
Pioglitazone fat kinetics
Slower, steadier decline tied to sustained insulin sensitization.
Dose-duration dependence
Higher dose and longer duration both deepen fat reduction.
Steatohepatitis Resolution
Inflammation clears once fat drops below the resolution threshold.
- ~63%: MASH resolution (sema, 72wk) (no fibrosis worsening)
- ~51%: MASH resolution (pio, 52wk) (biopsy-confirmed trials)
- possible: Fibrosis stage improvement (with sustained therapy)
- 24 wk: Minimum duration for resolution (in this sim)
What resolution means
Inflammatory cells clear and fat stays under threshold sustainably.
Resolution needs both low fat and enough elapsed treatment time.
Durability of response
Stopping therapy often lets liver fat and weight rebound.
Clinical takeaway
Sustained dosing, not a single milestone, drives lasting resolution.