When I rented my first off campus apartment at Penn State two years ago, my mom gave me some strange advice. “Never go grocery shopping on an empty stomach, you buy more food” she said in Russian over the phone during my first week settling into my new place. I shrugged this off as some typical weird mom advice that made no sense. Two weeks later, I was all out of water and found myself at Weis. There was just a slight problem, I was starving. What was supposed to be a quick trip to the grocery store for a case of water turned into a shopping cart full of Doritios, Oreos, and Ben & Jerry’s ice cream. As I am checking out and see my grocery total rising astronomically with every food item that gets scanned, I hear my mom in my head saying “never go grocery shopping on an empty stomach.” The whole car ride home the only thing I thought about was if she was true. Do you actually spend more money at the grocery store when you are hungry?
In this case, the null hypothesis is that you do not spend more money at the grocery store and the alternative hypothesis is that you do spend more money at the grocery store when you are hungry because something is going on. Scientists can either accept the null hypothesis or reject it. After giving this question some thought, it actually does make sense. The hungrier you are, the more food you buy. However, just because something makes sense does not mean that it is true. For example, Dr. Benjamin Spock thought that by having babies sleep on their stomach this would reduce the risk of them choking on their own vomit and dying in their sleep. Makes sense, right? However, his intuition was not backed by any scientific evidence and what was thought to be a good idea and logical ended up killing thousands of young children. So if you actually do spend more money at the grocery store when hungry, we are going to have to prove it by using the scientific method.
A study was conducted by The JAMA Network that tried to examine if you actually bought more items at the grocery store when hungry. The study was a randomized controlled trial where the researchers gathered 68 participants and randomly allocated them to one of two groups, the control group and the “treatment” group. The participants were told not to eat anything within 5 hours of showing up for the study. When the participants showed up, the treatment group was told to eat as many Wheat Thins as you want so you do not feel hungry while the control group was not given any food. Then, the participants were told to do some grocery shopping in a virtual grocery store. There was a variety of options available for purchase including healthy items like apples and broccoli and some not so healthy items like Twizzlers, Doritos, and red meat.
The results of the study were incredibly interesting. Unlike I had thought, the total amount of items purchased between the treatment group and the control were fairly similar. This meant that hungry people did not buy more items than the non-hungry group. The amount of healthy (low calorie) items was also fairly similar between the groups. However, the control group that did not eat Wheat Thins prior to going virtual grocery shopping, actually ended up buying a significantly larger amount of unhealthy, high caloric items. Although the hungry individuals did not buy more total items, the ended up purchasing more unhealthy items.
So if hungry people buy more unhealthy and caloric items, why is this so? A study conducted by the Max Planck Institute of Neurobiology says that people who are hungry tend to struggle weighing risk against benefit. The bag of Doritos might sound more appealing than the kale chips because your hungry mind may not being thinking about nutritional facts as much as what would taste the best right now. A person that is not hungry might take an extra couple minutes to think about the decision.
With that said, I do have a few concerns about the actual study. 48 out of the 68 participants were female. Would the data look different if there were more males in the study? Are males more likely to buy junk foods? Additionally, the grocery shopping was done online. According to Statista, only 0.4% of consumers prefer to shop online for their groceries. How would the data look if the participants were taken to a physical grocery store? Nonetheless, if you are concerned about buying too many unhealthy things at the grocery store, it won’t hurt if you have a snack before going shopping.
“Hunger Affects Decision Making and Perception of Risk.” Max Planck Gesellschaft. Max Planck Institute of Neurobiology, 25 June 2013. Web. 19 Oct. 2016.
Mela DJ, Aaron JI, Gatenby SJ. Relationships of consumer characteristics and food deprivation to food purchasing behavior. Physiol Behav. 1996;60(5):1331-1335
Tal, Aner, PhD. “Fattening Fasting: Hungry Grocery Shoppers Buy More Calories, Not More Food.” The JAMA Network. N.p., 24 June 2013. Web. 19 Oct. 2016.