Joined Nov 2015
757 Posts | 7+
Australia
Find a study of a medieval or ancient rural burial ground, and scroll to the stats. Then you'll see how big a problem 'malnutrition' was (i.e., not very).
I could be wrong. My opinion is population will expand rapidly until it meets the constraints. Then those at the bottom of the social scale will have a hard time.
By Tudor times the population had doubled. This could be due to more stable social conditions. Access to better quality tools. Expanding trade. The crafts expanded so there was surplus to support more tradesmen.
Going the Swedish data the availability of iron increased greatly. The price falling seven fold from 1350 to 1720. Iron seems to have been very affordable in the early days of the classical period. But there are signs iron was becoming scarce in the 3rd century Roman Empire. For example "lorica segmenta" that used 9 kg of iron fell out of use then. A shortage of iron tools would lead to reduced agricultural output.
My estimate is the availability of iron didn't match the early classical period per capita until the 17th century. Hence iron might have been a scarce commodity through out most of the dark and middle ages.
Here is an old thread on the subject of living conditions. There might be some others.
http://historum.com/medieval-byzantine-history/21422-peasant-life-middle-ages.html