When dietary saturated fat intake is reduced without a concurrent improvement in carbohydrate quality, there is no significant reduction in the incidence or mortality of coronary heart disease.

Study: Saturated Fat Restriction for Cardiovascular Disease Prevention: A Systematic Review and Meta-analysis of Randomized Controlled Trials

This study found that just eating less saturated fat didn’t lower heart disease or death rates — which matches the claim that you also need to eat better carbs to see any real benefit.

Study: Reduction in saturated fat intake for cardiovascular disease.

Cutting back on saturated fat didn’t明显 lower heart disease deaths or heart attacks, even when people replaced the fat with carbs — meaning just swapping fat for carbs, without making the carbs healthier, didn’t help much.

Study: Low-Fat Dietary Pattern and Risk of Cardiovascular Disease

The study cut down on fatty foods but didn’t really fix the carbs people were eating (like white bread or sugar). Even though they ate less saturated fat, their heart disease rates didn’t go down — which means just cutting fat isn’t enough if you’re still eating bad carbs.

Study: Effect of reducing saturated fat intake on cardiovascular disease in adults: an umbrella review

Cutting back on saturated fat alone didn’t lower the risk of dying from heart disease in this big review — which matches the claim that you also need to eat better carbs to see real benefits.