What is the milkshake study?

The "milkshake study" refers to a research experiment led by Alia Crum, which investigated the influence of mindset on physiological responses to food. Participants were given the same milkshake on two different occasions but informed it was either a high-calorie indulgent shake or a sensible low-calorie shake. Despite both shakes being identical with moderate calories, the study found that when participants believed they were consuming the high-calorie version, their levels of ghrelin—a hormone linked to hunger—decreased at a rate three times greater than when they believed they were consuming the sensible version. This has powerful implications on how belief itself can affect the body's hormonal response to food, regardless of its actual nutrient content 1.