BACKGROUND: Olive oil intake is inversely associated with risk of cardiometabolic diseases. However, its energy density has raised concerns about weight gain. OBJECTIVE: To examine the associations between long-term changes in olive oil consumption and changes in body weight in three prospective cohort studies. METHODS: We examined data from 121,119 females and males from the Nurses' Health Study (NHS, 1990-2010), NHSII (1991-2015), and Health Professionals Follow-up Study (HPFS, 1990-2014), aged 65 y or younger and who were free from chronic disease at baseline. We assessed the associations between changes in olive oil intake within each 4-y interval and concurrent body weight changes using multivariable linear regression models. Results across the 3 cohorts were pooled using inverse-variance weights. RESULTS: At baseline, the mean body mass index (BMI in kg/m CONCLUSIONS: A long-term increase in olive oil intake was inversely associated with body weight in middle-aged adults in the United States. Conversely, increased consumption of other added fats, such as butter and margarine, was positively associated with body weight.