Low triglycerides are uncommon, and in most cases they reflect something straightforward like diet, medication, or an overactive thyroid rather than a serious problem. A normal triglyceride level falls below 150 mg/dL, and most labs consider anything under about 50 mg/dL unusually low. If your results came back well below that threshold, there are several possible explanations worth understanding.
What Triglycerides Actually Do
Triglycerides are the main form of fat circulating in your blood. After you eat, your body converts calories it doesn’t need right away into triglycerides, which get stored in fat cells and released later for energy between meals. Your liver also produces triglycerides on its own. So a low reading means either your body isn’t making or absorbing enough fat, or it’s burning through fat faster than usual.
An Overactive Thyroid
One of the more common medical causes of low triglycerides is hyperthyroidism. When your thyroid gland produces too much hormone, it speeds up nearly every metabolic process in your body, including fat metabolism. Thyroid hormones cause rapid mobilization of fat from stored tissue, increase the concentration of fatty acids in your blood, and accelerate how quickly cells burn through those fatty acids. The net effect is that triglycerides get used up faster than they’re replenished, pulling your blood levels down.
If your triglycerides are low and you’re also experiencing unexplained weight loss, a racing heart, anxiety, or heat intolerance, thyroid function is a logical place to investigate. A simple blood test measuring thyroid hormone levels can confirm or rule this out quickly.
Problems Absorbing Fat
Your body can only put triglycerides into your bloodstream if your gut absorbs dietary fat properly in the first place. Conditions that damage the lining of the small intestine, particularly celiac disease, can significantly reduce blood lipid levels. In active celiac disease, the damaged intestine loses its ability to synthesize key proteins needed to build and transport cholesterol and triglycerides. Production of apolipoprotein A-1, the main protein carrier for HDL cholesterol, is virtually absent when the intestinal lining is severely inflamed.
Other malabsorption conditions, including chronic pancreatitis, inflammatory bowel disease, and small intestinal bacterial overgrowth, can have similar effects. If your low triglycerides come alongside symptoms like bloating, diarrhea, fatty stools, or unintentional weight loss, a digestive cause is worth exploring.
Diet and Calorie Intake
What you eat has a direct effect on your triglyceride levels. If you follow a very low-fat diet, restrict calories significantly, or fast regularly, your triglyceride levels will naturally drop because there’s simply less raw material for your body to convert into blood fats. This is especially true if you’re also physically active, since exercise burns triglycerides for fuel.
Interestingly, the type of diet matters in ways that aren’t always intuitive. Research from the Journal of Clinical Investigation found that low-fat, high-carbohydrate diets actually tend to raise triglycerides in most people, because the liver converts excess carbohydrates into fat. But if your overall calorie intake is low, or you’re eating a very restrictive diet with minimal fat and moderate carbohydrates, the opposite can happen. A diet that’s genuinely low in both fat and total calories will typically produce lower triglyceride readings.
Medications That Lower Triglycerides
If you take any cholesterol-lowering medication, that could easily explain a low reading. Three main classes of drugs reduce triglycerides:
- Statins like atorvastatin (Lipitor) and rosuvastatin (Crestor), prescribed primarily for cholesterol, also bring triglycerides down.
- Fibrates like fenofibrate and gemfibrozil, which target triglycerides specifically and can lower them substantially.
- Niacin (vitamin B3 in prescription doses), which reduces both triglycerides and LDL cholesterol.
If you’re on any of these and your triglycerides have dropped very low, it may simply mean the medication is working aggressively. Your doctor can adjust the dose if the level seems unnecessarily low.
Inherited Genetic Conditions
In rare cases, very low triglycerides run in families due to genetic mutations that affect how the body packages and transports fat. The most well-characterized of these is familial hypobetalipoproteinemia, caused by mutations in the APOB gene. People who carry one copy of the mutation (heterozygous) typically have triglyceride levels below 45 mg/dL. Those with two copies can have extremely low or nearly undetectable triglycerides.
A related condition called familial combined hypolipidemia, involving a different gene (ANGPTL3), produces very low triglycerides along with low HDL cholesterol. Another rare disorder, abetalipoproteinemia, caused by mutations in the MTTP gene, can produce similarly severe lipid deficiencies and may cause fat-soluble vitamin deficiencies, neurological symptoms, and digestive problems starting in childhood.
These genetic conditions are uncommon, but if your triglycerides have always been extremely low and no other explanation fits, genetic testing can identify them.
Are Low Triglycerides Harmful?
Most of the time, mildly low triglycerides aren’t dangerous and don’t need treatment. The medical world spends far more energy worrying about high triglycerides. But very low levels aren’t entirely without risk.
A study published in Neurology tracking women over time found that those in the lowest quartile of triglycerides (at or below 74 mg/dL fasting) had roughly double the risk of hemorrhagic stroke, the type caused by bleeding in the brain, compared to women with the highest triglyceride levels. This association held even after adjusting for LDL cholesterol and other risk factors. The relationship between very low blood lipids and hemorrhagic stroke likely involves the structural integrity of blood vessel walls, which depend partly on circulating fats to maintain their strength.
This doesn’t mean moderately low triglycerides are an emergency. The absolute risk of hemorrhagic stroke is small, and this finding comes primarily from observational research. But it does suggest that triglycerides that are consistently very low deserve some attention rather than being dismissed as automatically healthy.
What to Look Into Next
If your triglycerides came back low on routine bloodwork, the most practical next steps depend on how low the number actually is and whether you have other symptoms. A reading in the 40 to 60 mg/dL range in someone who exercises regularly, eats a lean diet, or takes a statin is rarely concerning. A reading well below 40 mg/dL, especially with no obvious dietary or medication explanation, is more unusual and worth investigating.
The most useful follow-up tests typically include thyroid hormone levels, a complete metabolic panel to assess liver function, and screening for malabsorption if you have any digestive symptoms. If your levels are extremely low and have been for as long as you can remember, or if close family members also have very low lipid levels, genetic testing for inherited lipid disorders can provide a definitive answer.