Preabsorptive

Preabsorptive is an adjective used in physiology and nutrition to describe processes or states that occur before nutrients from a meal are absorbed into the bloodstream. It is often contrasted with the absorptive (fed) state, when nutrients are entering the circulation, and the postabsorptive (fasting) state, when digestion has largely concluded and nutrient absorption is minimal.

In the preabsorptive period, the body relies on energy reserves to maintain blood glucose and supply tissues. Metabolic activities typically include hepatic glycogenolysis and gluconeogenesis to sustain glucose levels, along with lipolysis in adipose tissue to provide fatty acids for energy. Ketone body production may begin during longer fasts. Hormonal regulation commonly features relatively low insulin levels and higher concentrations of glucagon, epinephrine, cortisol, and growth hormone, with autonomic nervous system signals promoting hepatic glucose output and fat mobilization.

The preabsorptive state serves to bridge episodes of feeding, supporting metabolic stability between meals. It can encompass the interdigestive period and conditions of limited nutrient absorption, before the next meal’s nutrients are delivered to the gut and absorbed. In research, the term helps distinguish early, anticipatory, or fasting-related processes from those driven by nutrient absorption.

See also: postabsorptive state, absorptive state, cephalic phase, interdigestive period.