Browse evidence-based analysis of health-related claims and assertions
Saturated fat raises LDL cholesterol, but mostly the 'bigger, fluffier' kind that doesn't clog arteries as much as the small, sticky kind.
Mechanistic
Cutting back on saturated fat might lower your risk of having a stroke, even if it doesn't help much with heart disease or overall death risk.
Descriptive
Eating foods high in saturated fat doesn't seem to make you more likely to have a heart attack or die sooner, according to a review of many studies.
Even though athletes are super fit, their heart plaques aren’t more stable or ‘safer’ than those of healthy non-athletes—so being an elite athlete doesn’t make plaque less dangerous.
Correlational
Endurance athletes have more heart arteries affected by plaque buildup than healthy non-athletes—even when both groups have the same cholesterol and blood pressure levels.
Quantitative
For older male athletes, how much they exercise overall doesn’t seem to affect whether their heart arteries get more calcium buildup over time—it’s more about how hard they push during workouts.
For older male athletes, doing hard but not extreme workouts (like steady running or cycling) seems to be linked to less calcium buildup in heart arteries over time, compared to doing ultra-intense workouts.
For older male athletes who exercise a lot, doing very hard workouts (like sprinting or intense cycling) seems to be linked to more calcium buildup in the heart arteries over time, while moderate hard workouts might not have the same effect.
A key heart stress hormone doesn’t go up after a marathon, even in beginners — so it’s not useful for detecting heart strain in runners.
Beginner runners still show signs of heart stress a day after a marathon, but experienced runners’ hearts look normal again by then.
Experienced runners have less heart cell damage after a marathon than beginners, even though everyone’s heart gets stressed.
After running a marathon, everyone’s heart pumps a bit harder right after finishing, but it goes back to normal by the next day.
Runners who train harder and faster for years tend to have bigger heart chambers than those who run less, which helps their hearts pump more blood.
About 1 in 4 older male athletes who train regularly have significant plaque buildup in their heart arteries, even if they feel fine and have no symptoms.
For older male athletes who are otherwise low-risk for heart disease, doing a lot of exercise may help reduce plaque buildup in their heart arteries.
Older male athletes who have high heart disease risk and train a lot are much more likely to have serious plaque buildup in their heart arteries than those who train just as much but have lower heart risk.
Exercise helps women with PCOS handle fat better and improves their insulin sensitivity, but even after training, their muscles still react more strongly to fat overload than healthy women who don’t exercise.
Even after exercising, the body’s worst-case reaction to a fat overload stays the same — exercise helps you handle fat better, but doesn’t change the core way fat messes up your insulin system.
Women with PCOS who exercised regularly became fitter and had better blood sugar control, but didn’t lose weight or change their fat levels in the blood.
Women with PCOS are more sensitive to the negative effects of fat in the blood — their muscles struggle much more to use sugar when fat levels rise, compared to women without PCOS.
Women with PCOS who did 3 moderate workouts a week for 2 months became better at handling fat in their blood without losing weight — their muscles could use sugar more efficiently even when fat levels were high.
Even though endurance athletes have more plaque in their heart arteries, the dangerous, rupture-prone kind is actually rarer in them than in healthy non-athletes, which might explain why they rarely have heart attacks.
Endurance athletes have more heart arteries blocked by plaque than healthy non-athletes—even when both groups are fit and have normal cholesterol—meaning their arteries are affected in more places.
Even though endurance athletes and healthy non-athletes have about the same amount of calcium in their heart arteries, the athletes’ calcium levels are higher than 90% of people their age, suggesting their arteries are aging faster from exercise.