The bottles are sorted. Coconut oil stays. Avocado oil stays. The sunflower oil is gone. You watched enough, heard enough, read enough to know which cooking oil belongs in a kitchen that takes muscle building seriously.
A randomized double-blind trial fed two groups identical surplus calories from different fats, then put both groups inside an MRI scanner after seven weeks.
Which Cooking Oil Is Best for Building Muscle?
Surplus calories from polyunsaturated fat (sunflower oil) produced nearly three times more lean tissue than the same surplus from saturated fat (palm oil), despite identical weight gain on the scale. The partitioning advantage held in lean adults but disappeared in people with overweight.
— Rosqvist et al. 2014 · American Journal of Clinical Nutrition · n=37
Both groups gained 1.6 kilograms. Identical number on the scale, identical surplus on the meal plan. The bodies underneath were composed differently.
The sunflower oil group partitioned their surplus roughly evenly, about half to lean tissue and half to fat. The palm oil group stored four parts fat for every one part lean — with twice the visceral fat deposited and liver fat up 50%. Same calories consumed. Same weight gained. The oil on the pan decided where the surplus landed.
The oil that fitness culture ranks last, the seed oil, the one you physically removed from your shelf, built more muscle per calorie of surplus than the oil you kept. Your kitchen hierarchy and the evidence hierarchy run in opposite directions.
The oil that fitness culture ranks last, the seed oil, the one you physically removed from your shelf, built more muscle per calorie of surplus than the oil you kept.
Here is where this gets conditional. In adults carrying more body fat (BMI 25 to 32), the lean tissue advantage vanished. The gap between the two oils dropped so close to zero that no scanner could separate them. The partition benefit was specific to lean bodies in a surplus. Carry more body fat, and the oil type stops separating what the surplus builds.
Your cooking oil changes what a surplus builds inside your body, if your body is lean enough for the partition to matter. That condition puts the cooking oil question inside a larger one: whether a calorie really is a calorie when the fat source changes. Saturated vs unsaturated fat and body composition picks up there.
