The claim concerning Auschwitz is not correct or at least not without qualification at which point in time, in which Auschwitz camp, and concerning which prisoner group, given how the Nazis differentiated between different groups of prisoners based on their racial theory.

First of all, there is a need to differentiate between what the Nazis wrote about allotted food in Concentration Camps and what they did. Similarly to there existing written guidelines on when a guard could punish or kill a prisoner that had nothing to do with reality, there is an absolute necessity to look at the difference what the general guidelines stated a prisoner was to receive food-wise and what kind of food and caloric intake, they actually got.

According to guidelines produced in 1943 in Berlin, prisoners were to be allotted at least 1200 calories a day – more for hard workers – in the form of "food for hard workers", meaning heavy on beef or other meat, rye bread, and vitamin heavy crudités.

The reality however looked completely different: Concentration Camp prisoners would receive Ersatzcoffee and a piece of bread of varying size in the morning, another piece of bread for lunch and soup at dinner. Both soup and Ersatzcoffee were very heavy on the water, with the soup especially containing hardly anything other than warm water and often only rotten ingredients. The bread they received also was of questionable nutritional value. Most camp bakeries produced what the Germans called "Russenbrot", a mix of bread initially mandated for Russian foreign workers in Germany, which consisted of a mix of sawdust, leaves, and wood baked into something resembling bread (the receipt called for "50% rye grist, 20% sugar beet husks, 20% saw dust, and 10% wood chips or leaves").

Recalling the food they were served, most former prisoners e.g. recall that they were quite happy to receive the Ersatzcoffee in the morning with the coffee decoction in it since that provided something solid to eat since the constant diet of soup the Nazis kept the prisoners on produced an almost universal diarrhea in the camps.

Concerning the nutritional value of that diet, Christine Stahl calculated that in the Mauhtausen Concentration Camp, it delivered about 800 calories (whereas a grown person performing similar labor would need between 3000 and 4000), which in turn had to do with the camp administration calculating that most prisoners should and would only stay alive for 3 months maximum.

In Auschwitz, especially Auschwitz I Stammlager and Auschwitz III Monowitz, a similar diet of roughly equal nutritional value can be observed. In Auschwitz II Birkenau however, given that most inmates were Jewish a diet of even lower nutritional value can be observed. Going into the latter half of 1944 and with massive amounts of Hungarian Jews arriving in Auschwitz, in Birkenau daily caloric intake as low as 300 cal/day can be observed when the majority of prisoners started receiving nothing but the thin soup.

So, in short, the claim made here is not exactly right. Also, I think that one can observe the horror and injustice of the mentioned famine without needing to make such references, I mean 1200 cal/day and less is observably not very much for someone so I don't see the necessity of the comparison.