GTM Sauce

B2C · science-based fitness coaching app

How Built With Science grows

21 tactics and 22 figures from 1 interview.

A fitness coaching app built on a YouTube channel of about 3M subscribers, Built With Science turned its workout course into an app, launched it to that audience, then spent a year improving trial-to-paid and retention before buying any ads. Growth since then has come mainly from in-house Meta ads that do not rely on the creator, sent to a long quiz on its website, alongside YouTube videos and free tools.

Summary written 2026-09-26 from the tactics below. Figures are as founders stated them.

About Built With Science

What it is
Personalized workout and nutrition app with AI coaching, built on Jeremy Ethier's fitness YouTube channel
Who it's for
People wanting research-backed training and nutrition guidance, largely from Jeremy Ethier's YouTube audience
Business model
subscription with free trial, sold mainly through a web quiz funnel
Pricing
about $189/year or $30/month; 14-day free trial; tested: pay upfront with no trial for 20% off, with 30-day money-back guarantee; gym buddy plan: both users get 15% off
Launched
early January 2025
Team
Internal content team, product managers, in-house engineers; Meta ads run in-house

As described in the interviews, not independently verified.

Built With Science's 21 tactics

Built With Science · B2C · science-based fitness coaching app

Annual picks rose from ~60% to 75-80%, with no price change

Before: monthly and annual shown side by side. Variant: only the annual plan shown up front, with a Blinkist-style timeline above it: Day 1 you get your personalized plan; Day 7 your plan adapts to you; Day 12, before the 14-day free trial ends, 'we'll send you a reminder' and you can cancel anytime. Monthly is reachable via a 'view all plans' link. Price and positioning unchanged; UI-only change.

Workedpaywallpricing
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

15% of trial starts add a buddy; higher order value and better retention

Prompted by members asking for a family plan. The web quiz asks 'Do you have a gym buddy? Would you like to add them onto your plan?' Both users get 15% off. Those who decline see only a small gym buddy toggle on the pricing page, keeping the paywall simple. Buddies can see each other's workouts and meals and send nudges in the app.

Workedupsell-expansionpricing
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Quiz beat direct-to-store; now gets ~90% of traffic; same quiz in the iOS app did worse

About 90% of traffic goes to a long personalized quiz on the website. The quiz educates users on the product, overcomes objections, raises perceived value and shows how personalized the plan will be; answers are used to build the user's plan in the app. Tested traffic to the App Store vs the quiz: the quiz converted much higher. An almost identical quiz inside the iOS app converted worse than web, while the same quiz on Android converted about as well as web. They may retest App Store traffic later.

Workedweb-to-apponboarding
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Quite negative, even with a 30-day money-back guarantee

Paywall toggle: pay upfront with no trial and get 20% off (with a 30-day money-back guarantee), or toggle off to take the 14-day free trial. The copy framed no-trial as much better and the trial as losing out. Expected a win because much traffic is warm and trusts the brand. Inspired by in-app paywalls; not seen on web.

Failedpaywallpricing
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Story videos bring more trials than broad educational ones; old videos give steady monthly trials

Content-first: most long-form YouTube videos include a smooth, soft transition to the app in the middle or near the end rather than a hard pitch (hard pitches only on Instagram shorts). Every click from the video and description link is tracked per video, which showed that stories about a user who transformed their body on the app drive more trial starts than broad educational videos (a diet or a workout program) that reach more people. New videos are now planned around stories that tie into the product pitch.

Workedfounder-brandcontent
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Scaled from zero to ~$100K/month (host figure); 25% trial-to-paid

Deliberately avoided relying on Jeremy (already stretched) to remove the single point of failure of the YouTube channel. Creatives are B-roll 'sell' videos, testimonial content and many AI-made static ads. Angles are built around specific avatars and their pain points, sourced from surveys and past warm-traffic customers; winners are iterated while new avatars are slowly added. Run in-house rather than via an agency. After the Andromeda update, the focus is on better creatives rather than campaign/bid/targeting tinkering in Ads Manager.

Workedpaid-social
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Clickbait ads brought cheap trials but a huge drop in trial-to-paid

Kept Meta in-house so someone passionate about the product writes ads that don't over-promise. Tested click-baity ads that cheaply drive clicks and trial starts, but judged them on trial-to-paid; those showed a big drop. Ads built around a specific person's pain points and how the app uniquely solves them brought higher-quality trials.

Mixedpaid-social
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Kept $189/year since launch; 35-40% organic and ~25% Meta trial-to-paid

Priced at about $189/year or $30/month since launch and never changed. Positioned against the cost of a personal trainer ('a personal trainer in your pocket') rather than as a workout/nutrition tracker; Meta ads never call it a tracker but a coach guiding you. Trust from the YouTube channel supports the premium. Price testing deliberately postponed because price changes distort product metrics while they work on retention and trial-to-paid.

Workedpricingpositioning-niche
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Very strong lift after a few weeks, vs the version that shamed the trial

After the no-trial toggle lost, the documented hypothesis was that the copy framed no-trial as far better and the trial as losing out. Added a new test arm where both options are framed as good choices, neither as bad.

Workedpaywallexperimentation
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Hurt conversion; extra text overwhelmed buyers who were ready to start

To make the value proposition clearer, added more context/copy to one of the pricing pages as an A/B test.

Failedpaywall
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

~70% of tests fail first time; written notes turn failures into later winners

1) Use Amplitude to find the biggest drop-offs with the most room to improve across web and app onboarding. 2) For the chosen page (e.g. pricing), list as many problems as possible (lack of trust, unclear value proposition) and agree as a team on the biggest one. 3) Only then list solutions (e.g. testimonials for trust) and run the test. Document everything instead of Slacking an engineer, so failed tests can be diagnosed and iterated. Test bigger swings batching several hypotheses, since traffic is too low for many small tests; strip down if a batch fails. Apply winning messaging from one part of the funnel (quiz) to others (app).

Workedexperimentation
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Founder says it gives cleaner reads than email-hyped launches; no numbers

Previously announced every feature by email to all members, which inflated the engagement metrics they wanted to measure. Now: tell a beta pool (~100 long-time former course members plus ~1,000 beta testers) about the feature, collect feedback and iterate, then release it publicly with no announcement and watch the metrics. Only once there is signal it adds value do they announce it.

Workedfeature-development
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Founder says it lifted the floor for every channel; paid traffic later converted at 25%

Launched the app in January 2025 to the YouTube audience but ran no Meta ads until January 2026. Spent that year acting on launch feedback and improving trial-to-paid, retention and churn, reasoning that paid traffic converts much lower than warm organic traffic. Only once those numbers looked right did they add acquisition channels (Meta, SEO/AEO).

Workedproduct-activationpaid-social
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Some clips go viral; their hooks now shape new long videos

Recently onboarded a few clippers who cut existing long-form YouTube videos and post them on Instagram Reels and TikTok, run independently of Jeremy. Hooks from clips that go viral feed back into scripting future long-form videos.

Workedorganic-short-videougc-creators
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Took about a month to get a baseline to set the allowed cost per customer

Expecting cold Meta traffic to convert trial-to-paid lower than warm organic traffic, they first ran ads to gather data on the paid trial-to-paid rate, then used that baseline to calculate how much they could spend to acquire a customer before scaling and testing angles.

Workedanalytics-attributionpaid-social
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Working well, founder says; tools convert slightly better than blog posts

SEO from old blog posts once drove 30-40% of traffic but declined with AI search. In 2026 they hired an external AI-search consultant, optimized existing content, and built free web tools (calorie calculator, macro calculator, etc.) that give real value and transition into the web quiz. Tools tend to rank well in AI search.

Workedseoweb-to-app
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

One of customers' favorite features, founder says; no numbers

Jeremy AI: a chat trained on all of Jeremy's YouTube videos and blog history that answers fitness and nutrition questions as Jeremy would, and also reads the user's workout, nutrition and progress data to personalize answers. Built in-house by one engineer over a weekend.

Workedproduct-activationretention
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

Founder says it adds credibility; no numbers

Jeremy collaborates with lesser-known researchers, coaches and dieticians on videos about their findings, partners with UBC on studies, and runs studies inside the app with customers (e.g. a 3 vs 6 training days per week study, using in-app data). A team of dieticians, coaches and researchers watches for new research to inform content.

Workedcontentpositioning-niche
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

A launch spike, then a steady trickle; not a growth engine on its own

Converted a web course (spreadsheets for workouts and nutrition, ~100K members over the years) into an app after members kept requesting it. Hyped the launch to members, email lists and publicly on the ~3M-subscriber channel.

Mixedpr-launchemail
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

One of the year's top videos; decent but not major app conversion

Rented a full studio and brought in six or seven participants to measure body fat (DEXA), total energy expenditure and actual intake, over months of work, as a big bet on something new.

Mixedcontentfounder-brand
Sub Club by RevenueCat · 2026-09-02

Built With Science · B2C · science-based fitness coaching app

An engineer built a custom dashboard that validates each new trial as coming from Meta, because heavy organic reach makes Meta blend sources. Trial-to-paid is tracked per Meta trial and the highest-intent users are fed back to Meta as conversion signals.

Unknownanalytics-attributionpaid-social
Sub Club by RevenueCat · 2026-09-02

Built With Science by the numbers

MetricValueContextSaid in
users100K users
approximate
People who joined the web-based courses before the appSub Club by RevenueCat
2026-09-02
followers1M subscribers
approximate
YouTube subscribers when they decided to build the appSub Club by RevenueCat
2026-09-02
followers+1M subscribers/year
approximate
YouTube subscriber growth per yearSub Club by RevenueCat
2026-09-02
followers3M subscribers
approximate
YouTube subscribers at app launchSub Club by RevenueCat
2026-09-02
followers7M subscribers
approximate
YouTube subscribers nowSub Club by RevenueCat
2026-09-02
ad spendUSD 100K/month
approximate
Meta ad spend, scaled from zero in 2026, described by host as profitableSub Club by RevenueCat
2026-09-02
time to milestone1 months
approximate
Time to get a Meta trial-to-paid baseline before scaling spendSub Club by RevenueCat
2026-09-02
share90%
approximate
Share of (paid) traffic sent to the website quiz rather than the App StoreSub Club by RevenueCat
2026-09-02
priceUSD 189/year
approximate
Annual plan, unchanged since launchSub Club by RevenueCat
2026-09-02
priceUSD 30/month
approximate
Monthly planSub Club by RevenueCat
2026-09-02
conversion rate15%
approximate
Share of trial starts who add a gym buddy to their planSub Club by RevenueCat
2026-09-02
price15%Discount each user gets on the gym buddy two-person planSub Club by RevenueCat
2026-09-02
conversion rate35–40%
approximate
Trial -> paid for warm organic traffic from YouTubeSub Club by RevenueCat
2026-09-02
conversion rate25%
approximate
Trial -> paid for Meta ad trafficSub Club by RevenueCat
2026-09-02
share75–80%
approximate
Share of subscribers choosing the annual plan, after the annual-first pricing page experimentSub Club by RevenueCat
2026-09-02
share60%
approximate
Share choosing annual before the pricing page experiment (60/40 annual/monthly)Sub Club by RevenueCat
2026-09-02
share85%
approximate
Host's recap of annual share after the experiment; conflicts with guest's 75-80%Sub Club by RevenueCat
2026-09-02
share30–40%
approximate
Share of traffic historically coming from SEO (old blog posts), since declining with AI searchSub Club by RevenueCat
2026-09-02
share70%
estimate
Share of experiments that fail on the first attemptSub Club by RevenueCat
2026-09-02
count100 users
approximate
Core beta group of former web-course membersSub Club by RevenueCat
2026-09-02
count1,000 users
approximate
Wider beta tester poolSub Club by RevenueCat
2026-09-02
price20%Discount for paying upfront with no trial (vs 14-day free trial), in a paywall testSub Club by RevenueCat
2026-09-02

Topics

Interviews