Eating a diet low in fat and high in carbs makes the body less able to clear fat from the blood, causing triglyceride levels to rise sharply.

People with high triglycerides process fat differently than those with normal levels when eating a low-fat, high-carb diet — their bodies use different fat sources and clear fat slower, which may explain why this diet raises their triglycerides more than it does in others.

When people eat less fat and more carbs, their blood fat levels (triglycerides) go up a lot—even if their cholesterol stays the same—and high blood fat is linked to heart disease.

For people with a genetic tendency to have high triglycerides, eating a diet where 60% of calories come from carbohydrates raises fasting triglyceride levels and lowers HDL cholesterol, without changing total cholesterol levels.

After eating, people on a low-fat, high-carb diet have higher levels of fat, sugar, and insulin in their blood for longer than when they eat a diet with more fat, which might stress the body over time.

Eating fewer carbs might help people with type 2 diabetes who are overweight or obese improve their cholesterol numbers — lowering bad fats in the blood and raising good cholesterol — which could mean a healthier heart over time.