What the 5% calorie substitution represents
Nutrition trials often model fat changes as isocaloric swaps: holding total calories constant while replacing one fat type with another. Replacing roughly 5% of daily energy from saturated fat with monounsaturated fat is associated with an average LDL-C reduction in the order of about 10 mg/dL in pooled feeding data, though the exact figure varies by study and baseline.
Framing it as a swap matters because adding monounsaturated fat on top of an unchanged diet, rather than substituting for saturated fat, does not produce the same effect.
Why the replacement nutrient drives the result
The lipid response depends on what saturated fat is replaced with. Swapping toward monounsaturated or polyunsaturated fat generally lowers LDL-C, while swapping toward refined carbohydrate tends to lower HDL and can raise triglycerides instead. The diagram isolates the MUFA case to keep one variable in view.
Average effects from controlled studies do not predict any single person's outcome, which depends on genetics, the rest of the diet, and overall energy balance. This is general educational information, not personalized dietary or medical advice.