Harvard Doctor Reveals Why You Have Cravings and How to Stop Them | The Mel Robbins Podcast

KEYPOINTS

• 01

  Hunger and cravings run on separate systems

  Dr. Amy Shah, a double-board-certified physician trained at Cornell, Harvard and Columbia, describes hunger as the body's need for nutrients, signalled by hormones such as ghrelin, which rises on a daily timer. Cravings travel the dopamine pathway, the same one alcohol, drugs and sugar use. Ordering dessert when you're already full is a craving, not hunger.

• 02

  Ask whether you'd eat a bowl of vegetables

  Shah's quick test: if you wouldn't eat plain vegetables right now, you're not hungry. Next, drink a glass of water (sparkling with lemon or lime is fine) and check again in 15 minutes, because the brain easily confuses thirst with hunger. She calls the 64- or 80-ounce targets estimates rather than science.

• 03

  Ultra-processed food hijacks dopamine the way a first trip to Miami does

  Shah calls it the 'Miami phenomenon': South Beach feels thrilling on day one, and by day three you need the club to feel anything. Foods that don't exist in nature pack sugar without the fiber, water and nutrients of an apple, producing a dopamine spike she compares to cocaine, then a drop that leaves you irritable and wanting more. Her definition of ultra-processed: something you couldn't make in any kitchen, even with every ingredient in the world.

• 04

  Many poor food choices aren't simply a willpower failure

  Shah argues food companies design products to trigger the craving pathway. She cites findings that people eating the most ultra-processed food have 80% more poor mental-health days than those eating the least, and says over 70% of kids' diets are now ultra-processed. Her goal isn't zero, but cutting adults from roughly 60% to 30–40% so your own signals become audible again.

• 05

  Food and exercise may rival medication for depression

  Shah cites a South Australian analysis finding diet and exercise about 1.5 times more effective for depression than leading treatments, with medication and therapy grouped together, and says the authors recommended lifestyle change as first-line therapy. Mel frames it as hopeful rather than a reason to drop treatment, and the show's disclaimer says it doesn't replace a physician.

• 06

  Some foods support dopamine and serotonin

  Tyrosine-rich protein (dairy, soy, nuts, cherries) feeds dopamine production, so Shah favours a 'high-dopamine breakfast' such as cottage cheese with fruit and nuts. Tryptophan sources such as eggs, turkey, dairy, lean meat and fish, paired with a complex carb like sweet potato, squash or quinoa, support calming serotonin in the evening, which she says can help people who wake at night.

• 07

  Sleep, omega-3s and protein strengthen fullness signals

  Leptin, the fullness hormone, is about 33% lower after a bad night, Shah says, which is why you wake up starving. Omega-3s from salmon, algae oil or walnuts also help. GLP-1 drugs like Ozempic and Wegovy amplify a natural fullness hormone, and she says nuts, sleep and exercise raise it naturally. Protein also tells hunger hormones to stop.

• 08

  The gut and brain talk in both directions

  Gut bacteria produce dopamine and serotonin and signal the brain in at least four ways, including nerves, hormones and short-chain fatty acids. Shah describes a mouse study where researchers could tell which animals had received gut microbes from a person with schizophrenia just from their behaviour. She links the gut to anxiety, depression, ADHD, autism and Parkinson's, an area still being researched.

• 09

  Fermented foods beat probiotic pills, and exercise beats both

  Results for supplements like lactobacillus and Prevotella are inconsistent, Shah says, partly because the body attacks free bacteria. Bacteria inside the food matrix of yogurt, kimchi, kombucha, sauerkraut or raw apple cider vinegar survive better, and one study found four to six servings a day raised 'happy' bacteria most. Her 'number one probiotic' is exercise, which boosts anti-inflammatory short-chain fatty acids.

• 10

  Delay coffee and food for 45 minutes and eat in daylight

  Morning grogginess is largely adenosine, which clears in 30 to 40 minutes. Coffee only blocks its receptors, so drinking it immediately sets up a crash and a second or third cup. Shah argues intermittent fasting is often done backwards: eat during daylight and stop late-night eating, since the body processes sugar poorly once melatonin rises two to three hours before bed. Habitually skipping meals, she says, is linked to worse outcomes.