Disclosed are methods and compositions for increasing the triacylglycerol content of a cell by increasing the activity of a type 1 diacylglycerol acyltransferase (i.e., DGA2) and increasing the activity of a type 2 diacylglycerol acyltransferase (i.e., DGA1). In some embodiments, the triacylglycerol content of a cell is also modified by decreasing the activity of a triacylglycerol lipase in the same cell. Also disclosed are methods and compositions for increasing the triacylglycerol content of a cell by increasing the activity of a type 1 diacylglycerol acyltransferase (i.e., DGA2), or by increasing the activity of a type 3 diacylglycerol acyltransferase (i.e., DGA3).