Olive Oil vs Butter: A Weight Study
In February 2025, a large US study found that swapping butter or margarine for olive oil tracked with less long-term weight gain. Encouraging — and, as ever, observational.
What was studied
Published in the American Journal of Clinical Nutrition, the study tracked 121,119 US adults across three cohorts over 20–24 years. Greater olive-oil intake was associated with less long-term weight gain, while butter, margarine and some other fats were tied to gains.
It’s a big, careful study — but observational, so it shows association, not proof that oil itself prevents weight gain (olive-oil users tend to eat differently overall). The sensible reading isn’t “olive oil is slimming”; it’s that, calorie-for-calorie, a good fat in place of a worse one fits a healthier way of eating. Olive oil is food, not magic. See is olive oil a superfood?
Source, Feb 2025: American Journal of Clinical Nutrition (via News-Medical).