Unhealthy food choice is one of the main causes of being overweight. Nutritionists blame a particular category of food: junk food. Several authors have proposed a fat tax for reducing the junk food demand, but others have demonstrated that these taxes must be very high in order to be effective. Therefore, a warning label about calorie content may be an alternative way to reduce the consumption of junk food. In this exploratory study, using students as respondents, a high‐calorie warning label is explored with an incentive compatible valuation method. The results indicate that a high‐calorie warning label has little effect on respondents’ choices, even when they have no prior familiarity with the food.