“The Limited Nutritional Value of Cannibalism”, 1970-02 (; backlinks):
…A 50 kg man might yield 30 kg edible muscle mass if well and skillfully butchered, and 30 kg edible muscle would yield about 4.5 kg (4,500g) protein, or 4.0 kg protein assuming 90% digestibility. [no sources given]
Assuming quality protein requirements as 1g per kilogram of body weight, this would provide one-day’s protein requirements for ~60 60-kilogram adults. One man, in other words, serves 60, skimpily.
…While human flesh may serve as an emergency source of both protein and calories, it is doubtful that regular people-eating ever had much nutritional meaning.