You eat well and still have fatty liver. Your genes may be the reason.

GSTM1 encodes an enzyme responsible for the critical second phase of liver detoxification. Its job is to grab environmental toxins, heavy metals, and carcinogens and conjugate them with glutathione so they can be excreted safely. Without this step, toxins recirculate and accumulate in fat.

Roughly 50% of people carry a null genotype, meaning the entire GSTM1 gene is deleted. If this is you, you have zero functional copies of this enzyme. You lose the ability to conjugate a whole class of environmental toxins that most people clear without thinking. Pesticides, air pollution, mold metabolites, and heavy metals all depend on GSTM1 to be eliminated.

Without working GSTM1, your liver compensates by storing these toxins in fat cells to prevent them from damaging mitochondria and other critical structures. This is a survival mechanism, but it means your liver looks fatty on imaging even if you eat perfectly and exercise daily.

CYP2E1 is a phase I detoxification enzyme that metabolizes alcohol, acetaldehyde, and volatile organic compounds. It’s one of the first responders when alcohol or toxins enter the liver. Its other critical job is to neutralize acetaldehyde, a toxic byproduct of alcohol metabolism that damages cells and drives inflammation.

Certain genetic variants in CYP2E1 increase enzyme activity, meaning your liver produces more free radicals while processing toxins and alcohol. Roughly 20 to 30% of people carry variants that increase this activity. Higher CYP2E1 activity means more oxidative stress inside your liver cells, and more fat accumulation as a buffer against that stress. Even if you don’t drink much, smoking, secondhand smoke, and environmental chemical exposure activate this enzyme.

If you have an overactive CYP2E1 variant, your liver is constantly generating reactive oxygen species. Your mitochondria work overtime to neutralize the damage. Fat accumulates as your body’s way of managing the oxidative burden. You may notice that even small amounts of alcohol hit you harder or make you feel hungover longer.

MTHFR catalyzes a critical step in the methylation cycle, which fuels the production of glutathione, your liver’s primary detoxification molecule. Without sufficient methylation, your body cannot make enough glutathione to bind and eliminate toxins. MTHFR also controls the conversion of folate into its active form, which is required for detoxification and DNA repair.

The C677T variant, carried by roughly 40% of people of European ancestry, reduces MTHFR enzyme efficiency by 35 to 70%. This means your methylation cycle runs slower, glutathione production drops, and your detoxification capacity plummets. Heavy metals, pesticides, and environmental chemicals linger in your system longer because you lack the glutathione to conjugate and excrete them.

Your liver responds by storing these toxins in fat. You may also notice that standard B vitamin supplements don’t help your energy or metabolism the way they do for other people. This is because your body cannot convert regular folic acid or cyanocobalamin into active forms efficiently. Your liver is working harder to detoxify on less fuel.

SOD2 is an antioxidant enzyme that sits inside mitochondria and neutralizes superoxide, a particularly damaging free radical produced during energy production. It’s your first line of defense against oxidative stress at the cellular level. When SOD2 is working well, your mitochondria can handle the oxidative load of detoxification without accumulating damage.

The Val16Ala variant, present in roughly 40% of people, reduces SOD2 enzyme efficiency. With a less efficient SOD2, oxidative stress accumulates faster in your mitochondria, especially when your liver is processing toxins. Your cells respond to this mitochondrial damage by storing energy as fat, which is a less metabolically demanding form of fuel. Your liver also stores fat as a way to isolate damaging free radicals from vital structures.

If you have this variant, you may notice that detox protocols make you feel worse before better, or that you have difficulty with exercise tolerance. This is because standard detox increases the oxidative load on mitochondria that already have a harder time neutralizing free radicals. Your liver stores fat as a protective barrier against the damage.

ALDH2 neutralizes acetaldehyde, the toxic intermediate produced when your body metabolizes alcohol. It also clears acetaldehyde from smoking, secondhand smoke, and environmental air pollution. This enzyme is critical because acetaldehyde is far more damaging to cells than alcohol itself. It drives inflammation, damages mitochondria, and promotes fat accumulation.

The Glu487Lys variant (*2 allele) severely impairs ALDH2 function. Roughly 30 to 40% of people of East Asian ancestry carry this variant, and it occurs in roughly 5 to 10% of Europeans. With a deficient ALDH2, acetaldehyde accumulates in your system even from small amounts of alcohol, and exposure to air pollution and smoke becomes far more damaging. Your body has no choice but to store the accumulated acetaldehyde in fat cells.

If you carry this variant, you may flush easily when drinking, feel hungover from tiny amounts of alcohol, or notice that air pollution and smoke exposure trigger inflammation and fatigue. Your liver stores fat as a response to acetaldehyde toxicity that it cannot efficiently clear.

TNF is a cytokine that coordinates your immune response to toxins, pathogens, and environmental stressors. It’s essential for fighting infections and clearing damaged cells. But TNF also drives inflammation in the liver. When your detoxification system is overwhelmed by toxins or your mitochondria are under oxidative stress, TNF levels spike to trigger an inflammatory response.

The -308G>A variant, carried by roughly 30% of people, increases TNF production in response to environmental triggers. Higher TNF means your liver becomes more inflamed when exposed to toxins, mold, chemicals, or other stressors, and inflammation promotes fat accumulation in liver cells. This variant also drives stronger immune reactions to mold metabolites and chemical exposures, which then feed back into liver inflammation and fat storage.

If you have this TNF variant, you may notice that exposure to mold, air pollution, or chemical smells triggers fatigue, brain fog, or joint pain within hours. Your body is mounting an inflammatory response that overwhelms your detoxification system. Fat accumulates in your liver as inflammation escalates.