The famine in question (early '20s, not the later famine that resulted from de-kulakization) was made much worse because Lenin kept exporting food during it. The Bolsheviks did this because it was their only source of the foreign credit they needed to buy the machine tools and whatnot they needed to ramp up their industrial sector. I wouldn't call that "war communism", just straight "communism" as per Marx they felt industrialization was everything.
Interestingly, the only reason the death toll from this earlier famine wasn't even larger was that Herbert Hoover (of all people) organized an international relief effort that at one point was feeding about 10% of the USSR. When the agricultural situation improved, the Bolsheviks neglected to tell Hoover.