Final answer:
With a daily caloric deficit of 500 kcal, consuming only 1900 kcal/day against a maintenance requirement of 2400 kcal/day, Ryan is expected to lose approximately 4 pounds over the course of four weeks.
Step-by-step explanation:
Calculating Weight Loss through Caloric Deficit
When attempting to lose weight, a caloric deficit is necessary. This means consuming fewer calories than the body requires to maintain current weight. For Ryan, who needs 2400 kcal/day to maintain his weight, eating around 1900 kcals/day creates a deficit of 500 kcal daily. Over a week, he will have a total deficit of 3500 kcal, which approximately equates to losing one pound, as 3,500 kcal corresponds to about one pound of body fat. After four weeks with a consistent daily deficit of 500 kcal, Ryan can expect to lose approximately 4 pounds.