Hormonal

Overfeeding-induced insulin resistance is driven by the depletion of small, peripherally located intramyocellular lipid droplets and the subsequent accumulation of large lipid droplets and ceramides, rather than by an increase in total intramyocellular lipid content.

If you are concerned about insulin resistance, focus on maintaining physical activity levels that preserve small, peripheral muscle lipid droplets. High physical activity and efficient lipid oxidation are associated with resistance to weight gain and better insulin sensitivity, even during periods of overfeeding. The total amount of fat in your muscles matters less than how your body organizes that fat.