If men eating low-carb food swap out butter and fatty meats for oils like olive or fish oil, their blood gets more of the good fats that fight inflammation, the bad-to-good fat ratio drops a lot, and their cholesterol and triglycerides still improve.

If you swap out butter and fatty meats for oils and nuts, your 'bad' cholesterol goes down, which helps prevent clogged arteries and heart problems.

If you eat less saturated fat (like butter) and more unsaturated fat (like olive oil) while staying on a low-carb diet, your blood fat levels drop by about 11.5% and your body shows less signs of cellular stress.

Taking fish oil supplements with EPA and DHA over time makes the membranes of your red blood cells more filled with these types of fats, making them more flexible but also more prone to damage from oxidation.

If you swap out butter and fatty meats for bread, pasta, or olive oil, your blood might show higher levels of a type of fat particle called lipoprotein(a), which could be a concern for heart health — carbs raise it more than olive oil.

If you're a man who's keeping your weight steady and eating very few carbs, doubling the amount of butter and fatty meats you eat won't raise the level of saturated fat in your blood — meaning carbs might be the key link between what you eat and what shows up in your blood.