In a fascinating study conducted at Yale University, participants were each given a 380-calorie milkshake. Half the participants were told it was a sensible, 140-calorie shake, and half were told it was an indulgent, 620-calorie shake. In reality, everyone received the same 380-calorie milkshake. In a testament to the subjectivity of satiation, the people in the indulgent milkshake group rated themselves as fuller than those in the sensible milkshake group. But the researchers did not just rely on the participants’ self-report of how full they felt. The researchers also measured the levels of ghrelin, a gut hormone whose presence is associated with feeling hungry. They found lower levels of ghrelin in the people who thought they were drinking the indulgent shake, even though in reality they ingested the same number of calories! The researchers conclude that “mindset meaningfully affects physiological responses to food.”
In Parshat Ekev, Moshe informs Bnei Yisrael that when they enter the Land of Israel, “you will eat, be satisfied, and bless G-d.” This is the source for the commandment of Birkat HaMazon – to recite blessings after eating a meal that contains bread. The trigger for being obligated in the commandment is the feeling of satiety. Despite the subjectivity of satiation inherent in the verse, the rabbis of the Talmud set specific criteria to obligate Birkat HaMazon (either an olive sized or egg-sized amount of bread).
The Talmud presents an enigmatic Aggadic dialogue between G-d and the angels, where the angels ask G-d how He is able to show favor to the Jewish people (as is implied in the Priestly Blessing), as this does not seem to align with fairness and justice. G-d justifies his decision to show favor by pointing to the fact that even though the verse only requires Birkat HaMazon after being satiated, Bnei Yisrael recite the blessings even after only eating an olive or egg sized piece of bread.
This cryptic passage requires explanation. If the message is the importance of going above and beyond the bare requirements, is there any significance to choosing Birkat HaMazon as the example? Additionally, if the Biblical obligation is triggered only after feeling full, wouldn’t it be problematic to recite the blessings if one is not full? Wouldn’t this be considered a blessing made in vein (bracha le-vatala)?
Perhaps the significance of reciting the blessing on an olive or egg sized piece of bread is not that the Jewish people recite blessings even though they aren’t full. Rather, they worked on their attitude and changed their mindset, and as a consequence their biology, as it relates to being full. That is, they trained themselves to become satiated with the smaller amount.
The verse in Proverbs states “a righteous person eats to satisfy his soul.” Our ideal is to eat enough to have energy to serve G-d, not to indulge if there is no physical or spiritual benefit. While we should all consult the relevant health professionals for guidance on what and how much to eat, perhaps the message of the Talmud is that we could work on being mindful of our satiation and adjust our mindset to decrease the amount of food we require in order to become satiated.