High triglycerides are most commonly caused by eating too much sugar and refined carbohydrates, drinking excess alcohol, being physically inactive, or carrying extra weight. Levels below 150 mg/dL are considered healthy, 150 to 199 mg/dL is borderline high, 200 to 499 mg/dL is high, and anything at or above 500 mg/dL is very high. But diet and lifestyle are only part of the picture. Underlying medical conditions, genetics, and certain medications can all push triglycerides up, sometimes dramatically.
Sugar and Refined Carbs Are the Biggest Dietary Drivers
When most people think about triglycerides, they think about fatty food. But sugar is actually a more powerful trigger. Both table sugar (sucrose) and high-fructose corn syrup are at least 50% fructose, and fructose is the real problem. Your liver processes fructose differently than other nutrients. When you eat more sugar than your liver can store as glycogen, the excess gets converted directly into fat through a process called de novo lipogenesis. That fat gets packaged into large particles your liver releases into the bloodstream, raising your triglyceride levels.
Fructose also works against you from the other direction. It increases the levels of proteins that inhibit lipoprotein lipase, the enzyme responsible for breaking down triglyceride-rich particles in your blood. So excess sugar both increases the production of triglycerides and slows their removal. This double hit makes sugary drinks, candy, baked goods, and other sources of added sugar especially effective at raising levels. Refined carbohydrates like white bread, white rice, and pasta have a similar effect because they rapidly convert to glucose, triggering the same fat-production pathways in the liver through insulin signaling.
How Alcohol Raises Triglycerides
Alcohol increases triglycerides through multiple mechanisms. It stimulates the liver to produce large triglyceride-rich particles and release them into the bloodstream. At the same time, alcohol directly inhibits lipoprotein lipase activity, slowing the breakdown of those particles. This combination of increased production and decreased clearance is why even moderate drinking can nudge levels upward, while chronic heavy drinking often causes significant elevations.
Alcohol also impairs a key enzyme involved in regulating fat metabolism in the liver. Over time, this can lead to fat accumulation in liver tissue itself, a condition called fatty liver, which further worsens triglyceride levels.
Physical Inactivity Slows Triglyceride Clearance
Your muscles are one of the main sites where triglycerides get broken down and used for energy. When you’re sedentary, lipoprotein lipase activity drops in muscle tissue, meaning fewer triglyceride-rich particles get cleared from your blood. Regular physical activity does the opposite: it ramps up lipoprotein lipase, helping your body process and remove triglycerides more efficiently. This is one reason exercise can lower triglycerides fairly quickly, often within days of becoming more active, even before any weight loss occurs.
Insulin Resistance and Type 2 Diabetes
Insulin resistance is one of the most common medical causes of high triglycerides, and it creates a vicious cycle. When your cells stop responding properly to insulin, fat cells release more free fatty acids into the bloodstream. Those fatty acids flood the liver, which packages them into triglyceride-rich particles and ships them back out. Normally, insulin helps suppress this process, but when resistance develops, that brake is gone.
At the same time, insulin resistance impairs lipoprotein lipase activity in fat tissue, so fewer triglycerides get pulled out of the blood and stored properly. The result is a persistent state of elevated triglycerides that often accompanies prediabetes, type 2 diabetes, and metabolic syndrome. If you’ve been told your triglycerides are high and your blood sugar is also creeping up, the two problems are likely connected.
Hypothyroidism
Thyroid hormones play a direct role in triglyceride clearance. They upregulate lipoprotein lipase, the enzyme that breaks down triglyceride-carrying particles, and they increase the number of receptors on liver cells that pull remnant particles out of circulation. When thyroid hormone levels drop, as in hypothyroidism, both of these clearance pathways slow down. Triglyceride-rich particles linger in the bloodstream longer, and levels rise. Treating the underlying thyroid condition typically brings triglycerides back down.
Medications That Raise Triglycerides
A surprising number of common medications can push triglycerides higher, sometimes substantially. The effects vary by drug class:
- Beta-blockers (used for blood pressure and heart conditions) can increase triglycerides by 10 to 40%.
- Estrogen therapy can raise levels by around 40%, and in people with an underlying predisposition, it can trigger extreme elevations.
- Corticosteroids like prednisone raise triglycerides by a variable amount depending on dose and duration.
- Antipsychotic medications increase triglycerides by roughly 20 to 50%, with newer (second-generation) drugs generally having a bigger effect.
- Retinoids such as isotretinoin (used for severe acne) can raise triglycerides by 35 to 100%, likely by reducing the breakdown of triglyceride-rich particles.
- HIV protease inhibitors have the most dramatic effect, with reported increases of 15 to 200%.
- Thiazide and loop diuretics have more modest effects, typically raising levels by 5 to 15%.
If your triglycerides climbed after starting a new medication, that connection is worth discussing with your prescriber. In many cases, an alternative drug within the same class can be used.
Genetic Causes
Some people have high triglycerides primarily because of their genes. Familial hypertriglyceridemia is a relatively common inherited condition that causes moderate elevations. A rarer and more severe form, familial chylomicronemia syndrome (FCS), is caused by mutations in the gene for lipoprotein lipase. About 80% of FCS cases come from defects in both copies of this gene, while the remaining 20% involve mutations in related genes that help lipoprotein lipase function properly.
People with FCS often have triglycerides that soar into the thousands, even with a careful diet. But even milder genetic tendencies can amplify the effect of other triggers. You might eat the same diet as someone else and end up with significantly higher triglycerides simply because your body clears them less efficiently.
Pregnancy
Triglycerides rise naturally during pregnancy as part of the body’s strategy to supply energy to the developing baby. By the third trimester, average levels reach around 215 to 220 mg/dL, which would be classified as “high” outside of pregnancy but is considered a normal physiological change. Levels climb progressively from the second trimester onward and typically return to baseline after delivery. Extremely high pre-pregnancy triglycerides, however, can become dangerously elevated during pregnancy and may need monitoring.
Why Very High Levels Are Dangerous
Moderately elevated triglycerides contribute to cardiovascular risk over the long term. But very high levels carry an additional, more immediate danger: acute pancreatitis. The risk climbs steeply once triglycerides exceed 1,000 mg/dL. Among people with levels between 1,000 and 1,999 mg/dL, roughly 10% develop pancreatitis. Above 2,000 mg/dL, that prevalence doubles to about 20%. Pancreatitis is a painful and potentially life-threatening inflammation of the pancreas, which is why triglycerides above 500 mg/dL are treated more aggressively than lower elevations.
For most people, high triglycerides result from a combination of causes rather than a single one. A diet high in sugar, a sedentary routine, and early insulin resistance can stack on top of a genetic predisposition, with a medication adding further pressure. Identifying which factors are at play in your case is the first step toward bringing levels down effectively.