The way our bodies regulate appetite is a complex process, but the gut peptide ghrelin plays a key role. Famously known as the “hunger hormone,” ghrelin spikes before meals when we are hungry and returns to lower levels after mealtimes. Recent research shows that it isn’t just hunger levels that regulate ghrelin—it is our belief about how filling a food may be.

Study to Measure if Mindsets Matter

In a study published in the Health Psychology journal (1), researchers conducted a randomized control trial to determine the effect of mindset on satiety (feeling full) after consuming two different milkshakes. One was labeled “indulgent” and its fake food label showed it contained a whopping 640 calories. The other was labeled “sensible” and was shown to contain 140 calories. In reality, both milkshakes were identical and had 380 calories.

Researchers measured ghrelin levels in the blood at three different points: baseline (20 minutes), anticipatory (60 minutes) and postconsumption (90 minutes). During the first interval, participants were asked to read the fake nutritional labels. During the second interval, participants were asked to drink the milkshake and rate their satiety level.

Study Findings

Participants who thought they were consuming a high-calorie, indulgent milkshake ranked the drink as more filling than the sensible milkshake. More importantly, levels of ghrelin in the bloodstream reflected this. Ghrelin levels dropped—indicating fullness—when participants thought their drink was the higher calorie version. Ghrelin levels were consistent with what people believed they were consuming, rather than the nutritional value of the milkshake.

Study Implications

Beyond our physiological responses to food, it appears that the effect of food consumption on ghrelin may be psychologically mediated. If only we could shift our mindset about baby carrots and believe them to be as filling as a piece of chocolate cake! Future research may show if this is possible.