I have not spent time in the archives studying the famine. Most of my references are books by Indian economists. I am curious what effect the famine, a really large event, had on the Battle of Imphal which happened very soon afterwards and pretty close by.
Some generaliities. Famines are generally ascribed to a year when in fact they span a few. The famine is described at 1943 but in fact it started well before and was not fully relieved in 1944. Casualty estimates vary from 1 to 3 million. So a lot of people and it pretty amazing it was not seen as a global disaster at the time, but it really was not.
Modern economists maintain that famines are never about a shortage of food which is often plentiful in the region. Rather, they argue the food has not been got to the point of need often because of a war or smoother social disruption. That seems to be true on Bengal in 1943. There was plenty of surplus food in other regions of India but such was the uncertainty of war, the regions were unwilling to give it up to feed Bengal.
There was some other causes, all very disputed. They include that there was a policy of removing surplus food to ensure if the Japanese invaded there would be none for them. Surplus food in Bengal is a tenuous concept given how common hunger was generally.
There was a newly industrialised Calcutta to feed. Workers in factories were making ammunition and this meant food was being diverted for that purpose.
There was a war, so food was controlled indeed there was rationing in UK. But Indian economists have pointed out that most measurements of public health in UK went up, even during rationing, whereas in Bengal there was a famine. Rationing and food control done properly should not lead to a famine.
It is a subjective judgement but there was an attitude in the British Raj that famines were a feature of Bengal, too many people with too little land, often flooded. This attitude prevailed not just in 1943 but well before.
So what did this mean for the Battle of Imphal. Not certain yet but here are some thoughts.
Chandra Bose, the INA leader with the Japanese in 1944 was spreading a narrative of India on the verge of insurrections. He was Bengalis himself and the famine certainly feed the narrative he put forward. It turned out to be false but he was believed at the time. Thus the Bengal Famine played a part in the Japanese making the wrong intelligence assessment of the situation in India.
As noted before, few troops at Imphal were from Bengal. Most were from other parts of India. So there was not much direct impact on units.