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.

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.

Eating too many sugary, processed carbs and not enough good fats might make your body less responsive to insulin and mess up your cholesterol levels, which could raise your chance of heart disease—especially if you're older, female, don't move much, or are overweight.

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.

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.