From the Guidelines
Fasting is a highly effective method for reducing triglyceride levels in the blood, with intermittent fasting protocols showing a 15-30% reduction in triglyceride levels in many individuals. When you fast, your body depletes its glycogen stores and begins to use fat as an energy source, which leads to decreased triglyceride production in the liver and increased breakdown of existing triglycerides 1. The most recent and highest quality study, published in 2025, recommends addressing and treating lifestyle factors, such as obesity and metabolic syndrome, as well as secondary factors, such as diabetes and chronic liver or kidney disease, to reduce triglyceride levels 1.
Key Points to Consider
- Intermittent fasting protocols, such as time-restricted eating or alternate-day fasting, have been shown to reduce triglyceride levels by 15-30% in many individuals 1.
- A fasting period of at least 12 hours is typically needed to impact triglyceride metabolism, with longer fasts potentially yielding greater benefits.
- Fasting decreases insulin levels, which normally stimulates triglyceride production, while simultaneously activating hormone-sensitive lipase that breaks down stored triglycerides.
- For those with very high triglycerides (above 500 mg/dL), fasting should be implemented under medical supervision, as initial changes in diet can sometimes temporarily increase triglyceride levels before they improve 1.
Recommendations for Implementation
- Evaluate for secondary causes of hypertriglyceridemia and consider medical therapy to reduce the risk of pancreatitis in individuals with fasting triglyceride levels ≥500 mg/dL 1.
- Address and treat lifestyle factors, such as obesity and metabolic syndrome, as well as secondary factors, such as diabetes and chronic liver or kidney disease, to reduce triglyceride levels 1.
- Consider the addition of icosapent ethyl to reduce cardiovascular risk in individuals with ASCVD or other cardiovascular risk factors on a statin with managed LDL cholesterol but elevated triglycerides 1.
From the Research
Relationship Between Fasting and Triglyceride Levels
The relationship between fasting and triglyceride (TG) levels is complex, with various studies providing insights into this association.
- Fasting serum triglyceride levels of 150 mg per dL or higher are associated with increased risk of cardiovascular disease 2.
- Severely elevated triglyceride levels (500 mg per dL or higher) increase the risk of pancreatitis 2.
- A study found that fasting for 8 hours before measurement of serum triglyceride may be sufficient, as there was no significant difference in triglyceride levels between patients who had fasted for 8 hours and those who had done so for 12 hours 3.
- Elevated fasting TG levels are associated with incident cardiovascular events, and omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), lower TG levels and may have additional atheroprotective properties 4.
Fasting Time and Triglyceride Levels
- The optimal fasting time before measurement of serum triglyceride levels is a topic of debate, with some studies suggesting that fasting for 8 hours may be sufficient 3.
- A study found that fasting TG < 100 mg/dL was associated with a reduced mean 4-hour peak postprandial triglyceride level compared with fasting TG > 100 mg/dL 5.
- Nonfasting triglyceride levels were associated with incident cardiovascular events, independent of traditional cardiac risk factors, levels of other lipids, and markers of insulin resistance 6.
Triglyceride Levels and Cardiovascular Risk
- Triglyceride levels, both fasting and nonfasting, are associated with cardiovascular risk, with elevated levels increasing the risk of cardiovascular events 2, 4, 6.
- A study found that nonfasting triglyceride levels maintained a strong independent relationship with cardiovascular events in fully adjusted models 6.
- Omega-3 fatty acids, such as EPA, have been found to inhibit cholesterol crystal formation, inflammation, and oxidative modification of atherogenic lipoprotein particles, and may have additional atheroprotective properties compared to other TG-lowering therapies 4.