Elroy Is Eager to Lose Weight After Gaining 15 Pounds

Elroy is eager to lose weight after gaining 15 pounds during his freshman year of college. He decides to do a crash diet over the summer, which starts with cabbage soup and salad every day for two weeks. Elroy loses weight at first but quickly puts weight back on, even gaining an extra 5 pounds before returning to college. What is the most likely reason for this?

A) By choosing low fat foods, he increased ghrelin levels.
B) He ate too many vegetables that contained a high carbohydrate content.
C) He chose a diet that was not diverse and this led to an increase in his metabolism.
D) He lowered his metabolism by triggered mechanisms designed to prevent starvation.