"Freshman fifteen" is a term which means fifteen pounds, or about seven kilograms— the weight students might expect to gain in their first year of college. People used to talk about the "freshman ten." Before that, it was the "freshman five." Are freshman more inflated, or just the expression？ The fact is, many young men and women do put on extra weight when they start college. Some schools that have done research on the issue including Cornell University in Ithaca, New York, have found that freshmen gain an average of four pounds during their first twelve weeks, the equivalent of two kilograms. If weight gain continues at this rate, how long before they put on fifteen pounds？ The answer is forty-five weeks, or almost a year. The next question is, why do so many freshmen gain weight？ The answers listed by experts are not so surprising. One is poor diet: College students often eat foods high in fat and sugar and starch with no parents around to say no to junk food. Students may also miss meals. They could be in class or studying or just ... busy. In any case, those who miss meals are more likely to overeat when they do have food. Also, freshmen often use food to put their mind at ease. They have college pressures to deal with. Not only that, many are living away from home for the first time. Another reason college students gain weight is that they often do not get enough exercise. Finally, there is something else that can add up to the "freshman five" or ten or fifteen, alcohol. Alcohol is high in calories and this is especially true of beer. And, no, freshmen are not supposed to be drinking, not unless they are twenty-one, the legal drinking age in America. For many college students, the extra weight they put on in their freshman year can be as hard to escape as term papers and final exams.
Paragraph 1 is centered on______.

A. why freshmen put on weight in college
B. why freshmen worry about their weight
C. how the "freshman fifteen" gets its name
D. how the "freshman fifteen" amazes freshmen