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.

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.

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 low-carb or low-fat diets that are full of meat or sugary refined foods might raise your risk of heart disease by about 14% to 17% compared to eating healthier versions of those same diets.

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.

People who eat low-carb or low-fat diets full of sugary foods and meat have a 14% to 20% higher chance of getting heart disease than those who eat similar diets but with healthier foods.