HRZE Fasted/Fed in Newly Diagnosed TB

WHO recommends to take TB drugs while fasting: if TB drugs are taken with food, perhaps drug concentrations are too low; on the other hand: if this is not tolerated, drugs could also be taken with food. Do lower drug concentrations - with improved adherence to therapy - outweigh the disadvantage of lower drug blood concentrations over time? How exactly do the drug concentrations over time (pharmacokinetics) compare between fasting and fed conditions, especially in the early stage of TB treatment when patients are relatively sick, and relatively poorly tolerate TB drugs?