Would you believe that what you think you're eating can affect what you're actually eating? That there's a difference between the food placed in front of you -- and what you perceive that food to be? That your body may respond to what you *think* you're eating OVER what you're actually taking in?
The first time I was introduced to this topic was throughout the book Mind Over Medicine. Author Dr. Lissa Rankin wrote this book to discuss the body's innate ability to self-repair -- and highlight our capacity for influencing this ability through the power of the mind.
In Mind Over Medicine, Dr. Rankin shares a study done by Dr. Alia Crum, clinical psychologist at Yale University, called "Mind Over Milkshake". This study has since become one of my most favorite examples of how the mind can influence the physical body. It shows how our beliefs about the foods we're eating can impact the digestive system even more than the contents of the food itself.
To understand this study, we first need to talk about Ghrelin.
Ghrelin is the "hunger hormone" produced in the gut. It signals to your brain that it's time to eat. Ghrelin levels increase during a diet and intensify hunger, since they're secreted when the stomach is empty and designed to make sure you're fed. The higher the Ghrelin levels in your body, the more you need to eat to feel satisfied The lower the Ghrelin levels in your body, the less you need to eat to feel satisfied. All in all, Ghrelin can be seen as a signal for the digestive system. When levels are low, it's time to eat and even slow down metabolism in case it's awhile before you can.
However, as yet ghrelin seems rather a signal by which the digestive system regulates functions other than the digestive process itself. (Source.)
Through what's known as The Milkshake Study, Dr. Crum was curious to see if our beliefs affect how the body responds to food. To do so, Dr. Crum gave participants the same 380-calorie drink -- but with two different labels attached.
One group of participants believed they were given a "sensible shake", a healthy diet drink with only 140-calories. The other group of participants believed they were given an "indulgent shake", a full-fat and sugary drink with 680 calories.
Here's what happened:
Dr. Crum measured the hunger controlling hormone Ghrelin in blood samples at 3 time points... In the study, Dr. Crum discovered ghrelin levels (and thusly metabolism) were directly related to what the participants thought they were eating. When they had the supposedly indulgent milkshake, ghrelin levels plummeted, and when they consumed what they thought was a lighter treat, the ghrelin response was far less dramatic. (Source.)
In other words, as Dr. Crum says, “What we found is that when people believe they're consuming an indulgent, high-calorie milkshake, their bodies responded as if they had consumed more calories." The levels of satiety felt by participants in the study was consistent with what they believed they were consuming. (Instead of the actual nutritional value!)
The Milkshake Study is an example of the power of the Placebo Effect -- and an introduction into why it might be possible to use the mind to participate in our own healing. If you're curious to learn more, I highly recommend watching the TedTalk presented by Dr. Alia Crum on the Placebo Effect.