NPR Podcast Recap: Mind Over Milkshake

Alia Crum, a psychologist from Colombia University, recently questioned in an experiment the impact that food labels have on people psychologically, as well as the way the body corresponds to this psychological impact in the biological processing of food. After research especially on the placebo effect, Crum set up an experiment and began to take action. In the experiment, Crum made a batch of French vanilla milkshakes, all with the same calorie count of 300 calories. She then divvied the milkshakes up into two groups. One group she named Sensishake, a healthy milkshake containing only 140 calories (despite the fact that this was the 300 calorie shake). The other group was named Indulgence, a more decadent yet less healthy shake with 640 calories (though this shake, too, was the same 300 calorie milkshake). Then, she split those participating in her experiment into two groups, with one receiving Sensishake and one Indulgence - both groups were told the fake information about the shakes' calorie counts. Nurses were to monitor the participants' levels of a hormone called ghrelin before and after the consumption of the shakes, ghrelin being a hormone found in the gut that scientists often have deemed the "hunger hormone". Ghrelin levels rise when one is hungry and send a signal to the brain, telling it to find food; it also slows metabolism incase one may not find that food. Ghrelin levels drop after a large meal and send a signal to the brain, this time telling it to start metabolism and burn the calories. On the other hand, ghrelin levels drop considerably less after a smaller meal than after a bigger meal, and the corresponding signal sent to the brain tells it that one needs more food. For a while, scientists believed that the rising and falling of ghrelin levels correlated with the size of a meal and the nutrients consumed in that meal. However, Crum concluded through her experiment that that is not the case, and that ghrelin levels instead depend on what one believes they are consuming. She reached that conclusion because ghrelin levels dropped three times more when people thought they were having the Indulgent shake as opposed to people who had the Sensishake. Though more testing is necessary, Crum thinks scientists' perception of metabolism must change to account for peoples' beliefs about food and the significant impact those beliefs have.