The Freshman fifteen refers to an amount (somewhat arbitrarily set at fifteen pounds) of weight often gained during a student's first year at college.

The expression is commonly used in the United States and Canada. In Australia and New Zealand it is sometimes referred to as First Year Fatties, Fresher spread, or Fresher Five, the latter referring to a five kilogram gain.

The purported causes of this weight gain are increased alcohol intake and the consumption of fat and carbohydrate-rich cafeteria-style food and fast food in university dormitories. Many dining halls in United States universities are all-you-can-eat style and offer copious dessert choices. In addition, lack of sleep may lead to overeating and weight gain, because it lowers the level of leptin.