Question

What are discretionary calories?

Answer 1

Simply stated, discretionary calories are those calories that can be used ‘at your discretion’ after basic nutrition needs are met without exceeding energy requirements. It is the difference between your total energy requirement and the energy (calories) you consume to meet nutrient requirements.
for more reading https://www.bcm.edu/research/centers/childrens-nutrition-research-center/consumer/nyc/vol_2005_4/page4.htm