Macro partitioning
Overfeeding saturated fatty acids (SFAs) promotes hepatic and visceral fat storage, whereas overfeeding polyunsaturated fatty acids (PUFAs) promotes lean tissue gain in healthy, normal-weight individuals.
If you are in a caloric surplus, the type of fat you consume matters for body composition. Replacing saturated fats (like palm oil) with polyunsaturated fats (like sunflower oil) may help direct excess calories toward lean tissue rather than liver and visceral fat, provided you are healthy and normal-weight. This does not apply to obese or insulin-resistant individuals based on this study.
In conclusion, overeating SFAs promotes hepatic and visceral fat storage, whereas excess energy from PUFAs may instead promote lean tissue in healthy humans.
Why this rating
Double-blind, randomized controlled trial with MRI assessment, but limited to healthy, normal-weight, young adults (n=37), limiting generalizability to obese or insulin-resistant populations.
Source
Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans
Fredrik Rosqvist et al. · Diabetes · 2014
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