You finished your grilled chicken salad an hour ago—the one with no dressing, light on the quinoa, heavy on the virtue—and you’re already fantasizing about raiding the pantry. Meanwhile, your coworker who demolished a burger and fries at lunch seems perfectly content until dinner. What gives?
Here’s the uncomfortable truth that Yale researchers discovered: the problem isn’t that you didn’t eat enough. The problem is that you believed you were eating “healthy” food—and that belief literally changed your body’s hormonal response, leaving you hungrier than if you’d eaten the same exact meal with a different mindset.
In “The Expectation Effect,” science writer David Robson reveals one of the most counterintuitive findings in nutrition research: when you think you’re eating diet food, your hunger hormone levels barely budge, your metabolism slows down, and your gut empties faster. You’re not weak-willed. You’re experiencing a physiological response triggered by your expectations, not your actual food intake.
The Milkshake Study That Changed Everything
Alia Crum and her colleagues at Yale and Arizona State University ran an experiment that should make every dieter rethink their entire approach to “eating clean.”
They invited participants into the lab on two separate occasions to drink milkshakes. One was labeled “Indulgence: decadence you deserve” with marketing copy that read: “Indulge yourself with this rich and creamy blend of all our premium ingredients—sumptuously smooth ice cream, satin whole milk, and sweet vanilla.” The nutritional label claimed 620 calories, and the picture showed a glass loaded with ice cream, chocolate sauce, and sprinkles.
The other shake was called a “Sensi-Shake” for “guilt-free satisfaction.” The label promised: “Get sensible with the new light, healthy Sensi-Shake. It has all the taste without the guilt—no fat, no added sugar, and only 140 calories.” The illustration was a plain vanilla flower.
Here’s the kicker: both shakes were exactly identical. Both contained 380 calories.
Crum’s team took blood samples before and after participants drank the shakes, measuring levels of ghrelin—often called the “hunger hormone,” though Robson points out it’s better understood as an energy regulator.
The results were stark. After drinking the “indulgent” shake, participants’ ghrelin levels dropped exactly as you’d hope after a satisfying meal. Their bodies registered satiety and ramped up metabolism.
After the “sensible” shake? Ghrelin levels barely changed at all.
With nothing but a label change—no difference in actual nutrition—Crum’s team had manipulated the participants’ hormonal profiles. “When people think they are eating healthily, that’s associated with the sense of deprivation,” Crum concluded.
What Ghrelin Actually Does (And Why It Matters)
Before you dismiss this as just about “feeling” full versus “being” full, understand what ghrelin actually controls.
Ghrelin isn’t just a signal that says “I’m hungry, go eat something.” It’s a master switch for your entire energy management system.
When ghrelin levels are high, your body:
- Reduces its resting metabolic rate (burns fewer calories at rest)
- Starts preserving body fat in case of scarcity
- Makes you lethargic so you’ll expend less energy
When ghrelin levels drop after eating, your body:
- Increases metabolic rate
- Releases stored energy for use
- Makes you more physically active
This is why the expectation effect is so brutal for dieters. When you eat something labeled “healthy” or “low-calorie,” your ghrelin response is blunted. Your body interprets this as: We’re still in scarcity mode. Slow everything down and hold onto every ounce of fat we’ve got.
You’re physiologically primed to feel hungrier, move less, and burn fewer calories—all because of what you believed about your lunch, not what was actually in it.
The “Healthy” Chocolate Bar That Made People Hungrier Than Fasting
If the milkshake study seems hard to believe, consider this even more extreme finding that Robson cites.
Researchers gave participants a chocolate-flavored protein bar. Some were told it was “healthy.” Others were told it was “tasty.”
The people who ate the “healthy” bar weren’t just less satisfied than those who ate the “tasty” version of the same bar. They actually felt hungrier than people who had eaten nothing at all.
Read that again. Eating “healthy” food made them hungrier than fasting.
This isn’t about being grateful or having the right attitude. This is about your brain’s predictive processing system responding to expectations about nutrients—and those expectations directly controlling your digestion, metabolism, and hormonal responses.
Why “Healthy = Less Filling” Is Destroying Your Diet
Robson points to research showing that most people unconsciously link healthy foods with words like “hungry” and “starved.” When researchers survey people about their beliefs, they find strong agreement with statements like:
- “There is usually a trade-off between healthiness and tastiness of food”
- “There is no way to make food healthier without sacrificing taste”
- “Things that are good for me rarely taste good”
The higher someone scores on these beliefs, the higher their Body Mass Index.
This isn’t because they lack willpower. It’s because their beliefs create a deprivation mindset that sabotages their physiology. When you eat a salad while thinking “this is diet food, it won’t be satisfying,” you’re not just bummed out—you’re triggering a hormonal cascade that will leave you genuinely, physically hungrier than if you’d approached the same salad as a delicious, nourishing meal.
The same pasta salad will lead to lower satiety when labeled “healthy” compared to when it’s labeled “hearty.” Your gut actually empties the food faster, your insulin response changes, and your brain regions associated with energy regulation show measurably different activity—all based on the label, not the ingredients.
How Restaurants Keep You Trapped in the Deprivation Cycle
In 2019, Alia Crum analyzed the menus of 26 American chain restaurants that offer “healthy eating” options. The pattern was depressingly consistent.
Standard menu items used language suggesting enjoyment (“crazy,” “fun”), vice (“dangerous,” “sinful”), and decadence (“bliss,” “succulent,” “mouth-watering”). They emphasized texture (“crispy,” “creamy,” “gooey”) and taste (“tangy,” “flavorful”).
Healthy options? They emphasized simplicity (“plain,” “mild”), thinness (“lite,” “skinnylicious”), and deprivation (“fat free,” “low carb,” “guilt-free”).
The “healthy” foods were described by what they weren’t, not what they were. And every one of those deprivation-focused words was programming diners’ brains to expect less satisfaction, triggering exactly the hormonal response that would send them back to the kitchen two hours later.
When Crum’s team tested rewriting vegetable descriptions with indulgent language—”zesty ginger-turmeric sweet potatoes” instead of “cholesterol-free sweet potatoes,” or “sweet sizzlin’ green beans and crispy shallots” instead of “light ‘n’ low-carb green beans”—vegetable consumption increased by 29%.
More importantly, the people who ate the indulgently-described vegetables were less likely to snack afterward.
The Self-Fulfilling Prophecy of “Healthy” Eating
Here’s how the deprivation mindset becomes a self-fulfilling prophecy, according to Robson:
You visit a doctor who tells you you’re at risk for obesity. You respond with good intentions and stock up on low-calorie foods. But the moment you think “I’m eating healthy now,” you’ve activated associations with deprivation.
After each meal, you have higher levels of ghrelin running through your body. Your gut empties its contents more quickly. You feel more ravenous. Your cravings intensify. The belief that dieting is inherently difficult has become physiologically true.
Even someone with high willpower will struggle against this. You’re not fighting a lack of discipline—you’re fighting your body’s hormonal response to your own expectations.
What This Means for Your Next Meal
The solution isn’t to pretend kale is ice cream or to gaslight yourself into thinking Brussels sprouts taste like candy.
The solution is to stop seeing “healthy” and “pleasurable” as opposites.
When you eat nutrient-dense food, frame it as nourishing and satisfying—not as virtuous sacrifice. Don’t think “I’m being good by eating this salad instead of what I really want.” Think “This salad with roasted chicken, avocado, nuts, and a real dressing is genuinely delicious and will keep me satisfied for hours.”
Use sensual, indulgent language when you think about your food. Not lies—actual accurate descriptions that emphasize what the food is rather than what it isn’t.
Instead of “low-fat Greek yogurt,” think “thick, creamy yogurt with berries.”
Instead of “I’m eating grilled chicken because it’s healthy,” think “I’m eating this well-seasoned, juicy chicken because it tastes good and makes me feel strong.”
Pay attention to your actual experience while eating. Notice flavors, textures, satisfaction. Slow down. Let your brain register that you’re eating something substantial and enjoyable, not engaging in caloric penance.
This isn’t just positive thinking. It’s leveraging the same expectation effect that’s been working against you—but this time, using it to align your beliefs with your body’s actual needs.
The Bigger Picture
Robson’s research on food expectations is part of a larger pattern documented in “The Expectation Effect”: your beliefs about what you’re experiencing directly shape your physiological responses in measurable, concrete ways.
The food industry and diet culture have spent decades programming us to associate “healthy” with deprivation, sacrifice, and unsatisfying eating. Every “guilt-free” label, every “lite” product, every menu description emphasizing what’s been removed rather than what remains—it all reinforces the expectation that nourishing your body means punishing your palate.
And those expectations quite literally change your ghrelin response, your metabolism, your gut motility, and your subsequent hunger.
The good news? Once you understand the mechanism, you can start to reprogram your expectations. Not through willpower or positive affirmations, but through deliberately shifting how you think about and describe the food you’re eating.
Your body will follow where your mind leads. Make sure you’re leading it toward satisfaction, not deprivation.
FAQ SECTION
Q: Does this mean I can eat junk food as long as I believe it’s healthy?
A: No. Robson’s research from “The Expectation Effect” shows that expectations affect how your body responds to actual nutrients—they don’t replace nutrients. The point is that when you eat genuinely nourishing food, framing it as satisfying (rather than “diet food”) helps your body respond appropriately. Eating junk food while pretending it’s nutritious won’t give you the vitamins, minerals, fiber, and protein your body actually needs.
Q: How long does it take to change my food expectations and see results?
A: In Crum’s milkshake study published in “The Expectation Effect,” ghrelin responses changed immediately based on labeling. Your hormonal response shifts in real-time based on current expectations. However, changing deeply ingrained beliefs about healthy eating being inherently unsatisfying takes conscious practice over weeks or months. Start by reframing how you describe your next meal.
Q: What if I genuinely don’t enjoy healthy foods?
A: According to Robson’s research, part of your dissatisfaction likely stems from expectations, not taste. When researchers had people eat vegetables described with indulgent language (“zesty ginger-turmeric sweet potatoes”), consumption increased 29% and people enjoyed them more. Focus on preparation methods, seasonings, and descriptions that emphasize what foods are rather than what they lack. Many people discover they actually do enjoy nutritious foods once deprivation framing is removed.
Q: Can changing my mindset actually help me lose weight?
A: Robson’s findings in “The Expectation Effect” suggest that shifting from a deprivation mindset to a satisfaction mindset can improve your ghrelin response, metabolism, and subsequent hunger levels—all factors that affect weight management. However, this isn’t a magic solution. It’s one important piece of the puzzle that makes sustainable healthy eating easier by aligning your physiology with your goals instead of working against you.
Q: Is this the same as positive thinking or manifestation?
A: No. This isn’t about vague positivity or “believing” yourself thin. Robson documents specific, measurable physiological changes (ghrelin levels, metabolic rate, gut motility, brain activity) triggered by concrete expectations about food. It’s about understanding that your brain’s predictive processing system uses expectations to regulate bodily functions—and learning to provide accurate, satisfaction-focused expectations rather than deprivation-focused ones.