Charles Duhigg Lost 45 Lbs on a GLP-1 | Why Food Noise Vanishes

A Note from James:

I’m doing a big experiment in my life.

I recently started taking a GLP-1—tirzepatide, one of the so-called weight-loss drugs. But I didn’t start taking it specifically for weight loss. I had some blood work done for the first time in a long time, and there was a small indication that I might be pre-diabetic. My doctor suggested trying tirzepatide, and I wanted to understand what I was getting into.

The first person I wanted to talk to was Charles Duhigg, author of The Power of Habit and Supercommunicators. Charles has been taking a GLP-1 for about two years, and he says it has changed his life. He has lost around 45 pounds, but what interested me most was not just the weight loss. It was the habit change.

Charles explains that GLP-1s can quiet what people now call “food noise”—the constant background pull toward eating even when you are not actually hungry. When that noise quiets down, something interesting happens: you get a window where your old habits become more malleable.

That is the key idea of this conversation. The drug may help you eat less, but the bigger opportunity is that it gives you a chance to build new routines around food, exercise, alcohol, sleep, and identity. And if you build those habits while the window is open, those habits may continue even after you stop taking the medication.

We talk about food noise, cravings, the habit loop, keystone habits, stated versus revealed preferences, placebo effects, alcohol, sleep, exercise, blood sugar, identity, and whether GLP-1s are a lifelong drug or a tool for changing who you become.

Episode Description:

James is at the beginning of a GLP-1 experiment. Charles Duhigg is two years in.

In this conversation, Charles explains what he has learned from taking tirzepatide and from studying GLP-1s through the lens of habit formation. He describes the first phase of public understanding around these medications as weight loss. Phase two, he argues, is about behavior change.

The central concept is “food noise.” Charles describes it as the background craving that turns a basket of fries into an almost automatic behavior. You may not even notice the noise until it goes away. Once it quiets, the cue that normally triggers the habit loop weakens. That creates a temporary window where new habits can be built.

James and Charles use the GLP-1 experience to revisit the basic habit loop: cue, routine, reward. They talk about why habits feel automatic, why willpower is often the wrong tool, and why successful behavior change depends on identifying the cue and replacing the routine while still satisfying the underlying reward.

Charles also introduces the idea of GLP-1s as a catalyst for keystone habits. Eating less can make exercise easier. Drinking less can improve sleep. Better sleep can improve focus. Focus can improve work. One changed habit can set off a chain reaction.

The conversation then becomes more philosophical: Who are we if one part of the brain says “I want to be healthy,” while another part of the brain keeps revealing different preferences through action? Charles explains the difference between stated preferences and revealed preferences, and how repeated behavior can shift identity.

This is not a conversation about taking GLP-1s casually. It is a conversation about using a medical intervention deliberately, under appropriate medical guidance, as a chance to change the patterns that shape daily life.

Editorial Note:

This episode discusses prescription medications, including tirzepatide and semaglutide, as well as personal experiences with GLP-1 drugs. It should not be treated as medical advice.

GLP-1 medications can have side effects and risks, including gastrointestinal symptoms, dosing concerns, and contraindications for some patients. They should be used only under the supervision of a qualified medical professional. Any decision to start, stop, adjust, or combine medications should be made with a clinician.

James and Charles also discuss personal experience, habit change, appetite, alcohol cravings, and identity. Individual responses to these medications vary.

What You’ll Learn:

• Why Charles believes GLP-1s are entering “phase two”: not just weight loss, but habit change.
• What “food noise” feels like—and why people often do not notice it until it disappears.
• How GLP-1s may create a temporary “habit window” where old routines become easier to change.
• Why the habit loop—cue, routine, reward—matters when trying to change eating behavior.
• Why people often regain weight after stopping GLP-1s if they have not built new habits.
• How keystone habits can create a chain reaction across food, exercise, alcohol, sleep, and focus.
• Why micro habits may work better than a full lifestyle overhaul.
• How stated preferences and revealed preferences shape identity.
• Why eating less can make exercise easier, and why exercise can reinforce healthier choices.
• Why tracking behavior may be essential while taking a GLP-1.
• How placebo, alter egos, and rituals may influence identity and performance.
• Why the goal is not just losing weight, but becoming the kind of person whose habits support health.

Timestamped Chapters:

[03:36] James Begins His GLP-1 Experiment

James explains his early experience, including confusion between medication side effects and a bout of COVID.

[04:16] Charles’s Two-Year Experience

Charles describes taking tirzepatide, losing roughly 45 pounds, and why the biggest changes came months into the process.

[05:38] Phase One vs. Phase Two of GLP-1s

Phase one was about appetite and weight loss. Phase two, Charles argues, is about habits that can last.

[06:42] The Habit Window

How GLP-1s can quiet food noise and create a period where eating habits become more malleable.

[07:21] COVID, Side Effects, and Early Signals

James explains why his first few weeks were hard to interpret and why he is still figuring out what the medication is doing.

[09:00] What Food Noise Actually Feels Like

Charles uses the example of a basket of fries to explain cravings, cues, and automatic eating.

[09:55] The Habit Loop: Cue, Routine, Reward

Charles revisits the framework from The Power of Habit and applies it directly to food cravings.

[10:42] How GLP-1s Interrupt the Cue

The fries are still there, but the craving does not activate in the same way.

[11:40] What GLP-1s Do in the Body and Brain

Charles explains what researchers know about gastric emptying, glucagon-like peptides, and what remains uncertain about the brain.

[12:43] What Happens When You Stop

Why the medication alone may not be enough if old habits return after discontinuation.

[13:36] Pleasure, Food, Alcohol, and Anhedonia

Charles discusses reduced pleasure from food and alcohol, while separating clinical findings from broader claims about losing joy in life.

[15:54] Why Charles Stayed With It

Early changes were not dramatic weight loss, but a growing feeling that eating became more of a choice.

[16:40] Eating as a Keystone Habit

How changing food behavior can trigger changes in exercise, alcohol, sleep, focus, and work.

[19:31] Why Structure Matters

Charles explains why tracking and guided habit systems can help people see patterns they might miss on their own.

[20:32] What Changes Physically Over Time

Slower stomach emptying, feeling full longer, more stable blood sugar, and gradual changes in appetite.

[21:43] Stated Preferences vs. Revealed Preferences

Why one part of the brain says “I want to change,” while another part watches what you actually do.

[23:22] Identity Change and Habit Formation

How repeated behavior can teach the brain, “I am the kind of person who eats this way” or “I am the kind of person who exercises.”

[24:16] Placebo, Belief, and Becoming the Person You Want to Be

James and Charles explore whether placebo effects may work partly by changing identity.

[28:07] Alter Egos, Athletes, and Rituals

The conversation turns to Kobe Bryant, Michael Phelps, and how pre-performance routines can cue a desired identity.

[29:15] Start With Micro Habits

Charles explains why small behavior changes can compound more effectively than trying to overhaul an entire life at once.

[30:40] Charles’s First Micro Habits

Drinking less, eating fewer fries, stopping when full, and choosing healthier meals without relying on willpower.

[31:24] Feeling Full for the First Time

Charles describes the surprising experience of leaving food unfinished because his body had had enough.

[33:03] Why the Stomach Shrinks

The medication does not shrink the stomach directly; eating less over time changes how much food the body expects.

[33:21] Why Slower Stomach Emptying Helps

James asks why a weight-loss drug would slow digestion instead of speeding metabolism.

[35:00] The Cumulative Effect

Why the most visible changes often appear after several months, once habits, body size, and identity begin reinforcing each other.

[37:03] Is a GLP-1 a Lifelong Drug?

Charles explains what research and personal experience suggest about stopping, restarting, and maintaining results.

[38:56] James’s Health Motivation

James explains that his motivation is not primarily weight loss, but a desire to respond to possible pre-diabetic markers.

[39:36] Why Attitude Is Not Enough

Charles argues that wanting to be healthy helps, but habit change still requires structure.

[40:02] What Changed at Home

Charles explains how his family’s food did not need to change, even though his own choices and portions did.

[41:02] Weight, Body Composition, and Pre-Diabetes

Why blood sugar, insulin resistance, fat, and muscle matter more than the scale alone.

[42:38] Semaglutide, Tirzepatide, and What Comes Next

James and Charles compare different GLP-1 medications and discuss how newer drugs may work through multiple receptors.

[44:27] Will Charles Stop Taking It?

Charles explains why he may eventually discontinue the medication, but values having more choice over weight and behavior.

[45:24] Blood Work, Snoring, and Health Markers

Charles describes improvements in lab results, cholesterol, snoring, and overall health.

[46:31] Who Are We, Really?

James and Charles talk about identity, brain chemistry, sugar, alcohol, cravings, and the substances that shape behavior.

[48:32] Choosing the Person You Want to Become

Charles explains how better self-awareness can help people change habits deliberately rather than being pulled by cravings.

[49:00] Tracking the Experiment

Charles advises James to track food, feelings, and behavior so he can notice changes that might otherwise be invisible.

Additional Resources:

• Charles Duhigg Official Website
• The Power of Habit by Charles Duhigg
• Supercommunicators by Charles Duhigg
• Noom’s GLP-1 Companion / Habit Formation Announcement
• FDA: Zepbound Approval for Chronic Weight Management
• FDA: Concerns With Unapproved GLP-1 Drugs Used for Weight Loss
• BMJ: Weight Regain After Stopping Weight-Loss Medication
• Todd Herman — The Alter Ego Effect

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