Liver Enzymes (ALT, AST, GGT)
Your liver's report card. These three enzymes tell you whether your liver is inflamed, fatty, or stressed — often years before symptoms show up.
ALT, AST, and GGT are enzymes your liver releases into the bloodstream when it's under stress. Even mildly elevated levels — within the lab "normal" range — can signal fatty liver, which affects an estimated 30–40% of urban Indians. Optimal ranges are tighter than what the lab prints.
What are liver enzymes?
Your liver contains enzymes that help it process nutrients, detoxify chemicals, and produce bile. When liver cells are damaged or inflamed, they leak these enzymes into your bloodstream — which is what the blood test picks up.
- ALT (Alanine Aminotransferase) — the most liver-specific. Elevated ALT almost always means a liver problem.
- AST (Aspartate Aminotransferase) — found in the liver, heart, and muscles. Can be elevated from exercise, not just liver issues.
- GGT (Gamma-Glutamyl Transferase) — sensitive to alcohol and bile duct problems. Also rises with metabolic syndrome and obesity.
Think of these as smoke detectors. They don't tell you the size of the fire, but they tell you something is off.
What your numbers mean
| Enzyme | Lab "normal" | Optimal |
|---|---|---|
| ALT | <40 U/L | <25 U/L (M) · <20 U/L (F) |
| AST | <40 U/L | <25 U/L |
| GGT | <55 U/L (M) · <38 U/L (F) | <25 U/L |
AST/ALT ratio <1 = typical of fatty liver (NAFLD). AST/ALT ratio >2 with elevated GGT = suggests alcohol-related liver damage. AST > ALT with normal GGT = could be muscle-related (check if you exercised heavily before the test).
How to lower elevated liver enzymes
- Cut sugar and refined carbs — the single biggest driver of fatty liver in India. Excess fructose (from soft drinks, sweets, fruit juice) is directly metabolised by the liver and converts to fat.
- Lose visceral fat — even 5–7% weight loss can normalise ALT in most fatty liver cases.
- Limit alcohol — if your GGT is elevated, this is the first thing to address.
- Review medications — paracetamol, statins, antifungals, and certain antibiotics can raise liver enzymes. Don't stop anything without consulting your doctor.
- Consider liver-supportive supplements — NAC (600 mg 2x/day), milk thistle (silymarin 420 mg/day), and omega-3 can support liver recovery alongside lifestyle changes.
- Recheck in 8–12 weeks — liver enzymes respond relatively quickly to interventions.
Watch your liver enzymes trend over time
eterni tracks ALT, AST, and GGT across your reports — so you can see whether your lifestyle changes are actually reversing fatty liver.
Get early accessFrequently Asked Questions
What is a normal ALT level?
Most labs report ALT normal as up to 40 U/L, but research suggests optimal is below 25 U/L for men and below 20 U/L for women. An ALT of 35 might be "normal" on paper, but it could indicate early fatty liver — especially if your BMI is elevated.
What causes elevated liver enzymes?
The most common cause in India is non-alcoholic fatty liver disease (NAFLD), driven by excess carbohydrates, obesity, and insulin resistance. Other causes include alcohol, medications (paracetamol, statins, antibiotics), viral hepatitis (B and C), and intense exercise (which temporarily raises AST).
What's the difference between ALT and AST?
ALT is more liver-specific — when it's elevated, the problem is almost always in the liver. AST is found in the liver, heart, and muscles, so elevated AST alone can also come from a hard workout, muscle damage, or heart issues. The AST/ALT ratio helps: a ratio above 2 with elevated GGT suggests alcohol-related liver damage.
Can I lower my liver enzymes naturally?
Yes, in most cases. Reduce sugar and refined carbohydrate intake (the main driver of fatty liver in India), lose excess body fat (even 5% body weight reduction can normalise ALT), limit alcohol, avoid unnecessary paracetamol, and consider NAC or milk thistle for liver support. Recheck in 8–12 weeks.
The fatty liver epidemic in India
Non-alcoholic fatty liver disease (NAFLD) has become one of the most common chronic conditions in urban India, with prevalence estimated at 30–40%. The primary driver isn't alcohol — it's excess carbohydrate intake (especially refined carbs, sugar, and fruit juice) combined with sedentary lifestyles and visceral fat accumulation.
What makes NAFLD dangerous is its silent progression: fatty liver → steatohepatitis (NASH) → fibrosis → cirrhosis. ALT is the earliest signal. By the time you have symptoms, significant liver damage may have already occurred. This is why monitoring ALT as part of routine bloodwork is so important — especially if you carry weight around your midsection.
GGT as a metabolic and longevity marker
GGT has emerged as more than just a liver enzyme. Elevated GGT — even within the "normal" range — is independently associated with higher cardiovascular mortality, metabolic syndrome, and type 2 diabetes risk. In longevity research, keeping GGT below 20 U/L tracks with lower all-cause mortality risk. It's one of the most underappreciated markers on a routine LFT panel.
Know what's working. Know what's not.
eterni connects your lab results, supplements, and retests — so you can see the trajectory, not just a snapshot.
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