Aug 8, 2022 · 1h 10m · how-i-built-this
Noom: Saeju Jeong
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gold bands on the timeline = statements, start to end. Hover to read, click to jump. CC turns on captions
In this episode of How I Built This, host Guy Raz speaks with Noom co-founder and CEO Saeju Jeong about his journey from launching a heavy metal e-commerce business in South Korea to building a psychology-driven, multi-billion-dollar digital wellness platform through repeated pivots, near bankruptcy, and relentless resilience.
How this conversation actually went
Every chapter scored 0–10 on four independent dynamics. Hover any point for the reasoning behind the score. Guy holds 41.6% of the talking time here. How this is scored →
Guy as informed peer 3.7 Guest teaching 2.2 Guest disagreement 0.3 Guy pushing back 1.1
speaking balance: gold is Guy, purple is the guest (3 minute bins)
Sharpest disagreement ▶ 1:03:34 Saeju rejects the premise that Noom prescribes dietary restriction
Saeju firmly counters Guy's assumption about meal prescription, emphasizing that dictating meals creates stress and unsustainable habits.
Hardest push from Guy ▶ 44:01 Guy challenges the decision to abandon 5 million existing app downloadsGuy directly questions the strategic wisdom of sunsetting an established #1 app rather than iterating within its existing user base.
Biggest teaching moment ▶ 1:04:49 Saeju breaks down the behavioral psychology behind food color-codingSaeju educates Guy on how red labels trigger counterproductive psychological guilt, prompting Noom to switch to orange to foster sustainable moderation.
Guy holds their own ▶ 44:01 Guy demonstrates product distribution expertiseGuy offers sharp operational critique about leverage and distribution, leading the founder to admit that killing the original app was a mistake.
the scores for every segment, with the reasoning behind each
| Chapter | Topic | Guy as informed peer | Guest teaching | Guest disagreement | Guy pushing back | Why |
|---|---|---|---|---|---|---|
| Prologue: Surviving on Low Funds in a Sweltering Office | 6 | 0 | 0 | 0 | Guy Raz sets up the episode with an in-depth prologue analyzing Richard Thaler and Cass Sunstein's book Nudge, connecting behavioral economics directly to Noom's product thesis. | |
| Childhood in Yeosu and Academic Pressure to Enter Medicine | 2 | 3 | 0 | 0 | Saeju explains South Korean academic pressure and the national exam day atmosphere, while Guy actively listens and asks clarifying questions about medical school expectations. | |
| Discovering a Lifelong Passion for Heavy Metal | 3 | 2 | 0 | 0 | A friendly cultural exchange where Guy recognizes heavy metal bands and Saeju shares his youthful discovery of extreme metal and his family's supportive reaction. | |
| Launching Buy Hard Productions E-Commerce Venture | 3 | 2 | 0 | 0 | Guy clarifies the business model of Buy Hard Productions, distinguishing an import/distribution service from an original recording studio. | |
| Tragic Loss of Father and Family Reorientation | 1 | 1 | 0 | 0 | Saeju shares the emotional narrative of his father's terminal cancer diagnosis, and Guy maintains a supportive, reverent listening posture. | |
| Military Service and Shifting Perspective on Adversity | 1 | 2 | 0 | 0 | Saeju describes the pivotal confrontation during military service that shifted his mindset from grief to living up to his father's expectations. | |
| Arriving in New York and Overcoming Isolation | 3 | 1 | 0 | 0 | Guy injects humor regarding Long Island geography as Saeju candidly shares his extreme isolation and calling phone support just to practice English. | |
| Serendipitous Meeting with Artem Petakov | 2 | 1 | 0 | 0 | Saeju details the serendipitous encounter with Artem Petakov and their immediate connection over shared immigrant backgrounds. | |
| Reframing Healthcare from Sick Care to Prevention | 4 | 3 | 0 | 0 | Guy cleanly articulates Saeju's father's core philosophical tension between reactive sick care management and preventative wellness. | |
| Founding Work Smart Labs and the Smart Bike Prototype | 5 | 2 | 0 | 1 | Guy contextualizes why venture capitalists rejected the smart stationary bike prototype by referencing hardware manufacturing and total addressable market constraints. | |
| Mid-Episode Transition: Facing Near Failure | 3 | 3 | 0 | 0 | Saeju outlines the unexpected user behavior data showing that 90% of CardioTrainer users were primarily using the app for step-counting to lose weight. | |
| From Calorific to a Holistic Behavioral Strategy | 7 | 2 | 1 | 6 | Guy pushes back on the decision to completely kill CardioTrainer rather than repurposing its 5 million downloads for Calorific, prompting Saeju to concede Guy is right in hindsight. | |
| Rebranding to Noom and Tackling Chronic Health Habits | 6 | 4 | 2 | 5 | Guy raises biological and genetic obstacles to weight loss, questioning whether behavioral interventions alone are sufficient, and Saeju responds by defending personalized behavioral frameworks. | |
| Integrating Human Coaches and Transitioning to Subscriptions | 4 | 3 | 0 | 0 | Saeju explains the critical findings around human coaches versus pure AI and the resulting painful fallout among product staff when transitioning away from freemium. | |
| Mid-Episode Transition: The Subscription Overhaul | 5 | 2 | 0 | 3 | Guy directly asks about user backlash and legal scrutiny regarding hard-to-cancel subscription renewals, and Saeju explains their revamped self-cancellation architecture. | |
| The Science of Color Coding and Sustainable Eating | 4 | 6 | 3 | 3 | When Guy suggests Noom must mathematically enforce strict dietary restrictions, Saeju rejects the premise, explaining that restrictive dieting causes psychological stress and yo-yo effects. | |
| Scaling Through the Pandemic and Evaluating Success | 4 | 1 | 0 | 0 | Guy asks the signature How I Built This question regarding skill versus luck, and Saeju responds with humble gratitude toward his early team and investors. |
Statements from this episode (14)
Jeong: Father's Passing Completely Changed How He Views the World
“Basically my father's departure and you know, the last month with him was a precious gift to me and to my family, and that event completely changed the way I view the world still today.”
Jeong generated over $1 million with his heavy metal venture, Buyhard Production
“So, when I left Korea, my mom, I told my mom, mom, I figure from Byhar production, at first, I made more than a million dollars, mom.”
Jeong arrived in NY with under $5,000 after giving earnings to mother
“Below 5000 dollars, actually and the reason is I gave all my money to my mom, what I made from By Heart, and I reset myself again.”
Jeong: Traditional healthcare functions merely as reactive "sick care management"
“He always told patients to make sure that they have a healthy lifestyle. But Like, majority of patients develop the conditions, and he has to do, in other words, sick care management. So, he left a very big question to me that, why? Why are the societies point…”
Noom's earliest prototype was an interactive screen for a stationary bike
“So our first prototype was interactive screen with a stationary bike that you can touch the screen, you can follow the guide from the screen, all that.”
Noom precursors faced two years of rejections and dwindled to $2,700
“After two years of straight, like getting a no from all the NJ investors or VCs or even friends, It became clear. And the reality was, Guy, that we didn't have much money left in the bank. I remember we had, like, 2700 dollars”
Jeong: Early app CardioTrainer hit 5 million downloads in six months
“We, yeah, we received like five million downloads within six months by then. And by the time that was a break, like record breaking number.”
Jeong: Over 90% of CardioTrainer users ignored main features for step counting
“Majority of our users, 90% plus more, our users are not using the major features, which is tracking their running or the cycling. They are actually using our product for parameters.”
Jeong: Calorific became a top downloaded app within three months with zero marketing
“We literally launched the Colorific with no marketing budget. We just, we were probably naive by then. We launched the product. We firmly believe that if the product is good, people will somehow just download it. And matter of fact, the Colorific actually rece…”
Noom co-founder: True empathy cannot be recreated by computers
“Empathy cannot be made up. Empathy cannot be recreated by computer.”
Jeong: Paywalls filter uncommitted users and yield higher-quality behavioral data
“We had a moment that we need to put the price, price wall. That is the way we can weed out who are not ready to commit for adopting healthy behavior, and that is the way also, as we are a product company, we can actually gather, gather higher quality data in o…”
Jeong: Noom subscriptions can now be canceled online in three clicks
“So matter of fact, we invested a ton into that the opportunity, and now the 100% self-cancellation is right there. You can, you have three clicks, then you can cancel that.”
Jeong: Strict diets fail after two weeks, triggering yo-yo behaviors
“The thing is, if we limit our users, there's enough study in our own, from our experience, if we limit our users, do this, not that, they may work for maybe two weeks, but it Cannot work more than that, and that create, as we know, and which make me sad, yo-yo…”
Noom changed its "red" food category to orange to prevent user misconceptions
“By the way, we actually wanted to update our food color system from red to orange. The reason is, because we use the red, people associate the red color that means, oh, this is bad, this is warning, blah, blah. It's not true. Red category food is is we need to…”