Do different types of fat have different effects on body composition?
It is well established that caloric balance (ingested calories minus calories burned) is the most important determinant of changes in bodyweight. However, this does not mean that all foods or nutrients will have exactly the same impact on body composition.
Athletes intentionally overeat (also known as bulking) to maximize muscle mass gains. However, ideally they would gain as much muscle as possible, while minimizing the amount of fat they put on.
In the current study, subjects overfed (750 calories a day) on cupcakes with polyunsaturated fat (sunflower oil) or on cupcakes with saturated fat (palm oil).
After 7 weeks, both groups gained similar amounts of weight (~1.8 kg). However, in the saturated fat group about 80% of the weight that was gained was fat mass. In contrast, in the polyunsaturated fat group only about 50% of the weight gained was fat mass. Conversely, in the polyunsaturated fat group a much higher percentage of the weight gain consisted out of lean mass (50 vs 20%, respectively).
In addition, liver and visceral (i.e. between the organs in the abdominal region) fat deposition was lower in the polyunsaturated group. This type of fat storage is very bad for your metabolic health (2).
Go to the next study in the fat series:
Processing peanuts increases fat absorption?
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