Which molecule is less soluble in water–a fat or a phospholipid? why? which molecule is less soluble in water–a fat or a phospholipid? why? a fat molecule is less soluble in water because it has more carbons and hydrogens than a phospholipid. a phospholipid is less soluble in water because it is smaller than a fat molecule. a fat molecule is less soluble in water because it has three non-polar fatty acids and no polar or charged head like a phospholipid has. a phospholipid is less soluble in water because even though it has one end that is hydrophilic, the end that is hydrophobic is larger?