Almost everyone who switched to a low-fat, high-carb diet saw their blood fat levels go up—only one person didn’t, which means this effect happens in nearly all people.

When you swap fats (like butter or oil) for carbs (like bread or sugar), your blood fat levels (triglycerides) tend to go up.

Intermittent fasting might help lower triglycerides a little more than regular calorie cutting in people with overweight or obesity, but the difference is so small that scientists can't say for sure it's not just due to chance.

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.

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.

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.