Last night I came across the Wikipedia articles on both these books that made those kind of claims, and I was wondering where on the scale between "conspiracy theory" and "credible" these two were:

Other Losses is a 1989 book by Canadian writer James Bacque, in which Bacque alleges that U.S. General Dwight Eisenhower intentionally caused the deaths by starvation or exposure of around a million German prisoners of war held in Western internment camps briefly after the Second World War. Other Losses charges that hundreds of thousands of German prisoners that had fled the Eastern front were designated as "Disarmed Enemy Forces" in order to avoid recognition under the third Geneva Convention, for the purpose of carrying out their deaths through disease or slow starvation. Other Losses cites documents in the U.S. National Archives and interviews with people who stated they witnessed the events.

The book claims that there was a "method of genocide" in the banning of Red Cross inspectors, the returning of food aid, the policy regarding shelter building, and soldier ration policy.

And the other one:

An Eye for an Eye: The Untold Story of Jewish Revenge Against Germans in 1945 is a 1993 book by John Sack, in which Sack states that some Jews in Eastern Europe took revenge on their former captors while overseeing over 1,000 concentration camps in Poland for German civilians. Sack provides details of the imprisonment of 200,000 Germans "many of them starved, beaten and tortured" and estimates that "more than 60,000 died at the hands of a largely Jewish-run security organisation." A professor of Jewish history at Brandeis University, Antony Polonsky, said that his "research appears to be sound",[1] but he and other reviewers have questioned the "extent of Jewish persecution of Germans", in Sack's book.[2][3][4]