What started as a weekend project in high school led to a deal most founders wait a lifetime for
On an average weekday afternoon, most high schoolers would spend their time thinking about the next class, practice, or deadline. But not Zach Yadegari and Henry Langmack.
Instead, the two teenage co-founders spent their time thinking about why calorie tracking feels like punishment – and it turned into a viral calorie-counting app that’s now been snapped up by one of the biggest names in the category, MyFitnessPal.
“We built Cal AI in our high school classrooms and grew it to one of the fastest-growing apps in the category, generating over $40 million in sales in the last 12 months,“ Yadegari, the now-19-year-old CEO, says. “It exceeded all expectations.”
How two teenagers spotted a frustration millions felt
Picture the same failure loop play out – over and over – in gym classes and group chats. Someone downloads a calorie app on a Monday, full of intent. They log breakfast and lunch once, maybe twice.
Then the friction of searching, typing, guessing, and portioning out ingredients arrives. By Wednesday, the streak is gone because the process feels more like paperwork than a newly-forming habit.
In 2024, Yadegari and Langmack launched Cal AI, a viral photo-based calorie counting app designed to kill that friction at the source.
Instead of turning dinner into data entry, Cal AI tries to make logging feel instant. Users simply snap a picture, get an estimate, and move on with their day.
Cal AI has said it combined AI models, including ones from OpenAI and Anthropic, with retrieval techniques trained on open food and calorie datasets to improve recognition. The team has also claimed the system reaches about 90% accuracy for many foods, though independent validation details haven’t been published.
Solid tech, however, was only half the equation when it came to building a million-dollar consumer app in under two years time. The real inflection point came with distribution, which can be the part most early consumer founders underestimate.
They built the app, but the internet made it work
The fledgling startup’s growth really took off thanks to social media and influencer marketing, helping the app reach 8.3 million downloads by July 2025.
The founders, who knew how powerful it can be to capture attention online, leaned into viral creator content and platforms like TikTok and X to spread the word in a fun, organic, and cost-effective way.
The business model followed the same founder pragmatism. Cal AI ran on subscriptions, offering options like $2.49 per week or $29.99 per year. Free trials, too, helped pull users through the first “this actually works” moment.
Meanwhile, the team scaled to around 30 people, pushing continual product improvements and keeping the growth loop alive.
And then the headline became inevitable.
Earlier this week, MyFitnessPal announced it had acquired Cal AI, framing the deal as part of a broader push to expand its AI-powered nutrition tracking portfolio.
It positioned the two products as “distinct but complementary,” arguing that no single experience fit every user. While some want depth and structure, others want speed and simplicity.
TechCrunch reported the acquisition had closed in December 2025, after MyFitnessPal had pursued Cal AI for nearly a year.
MyFitnessPal also said Cal AI had reached 15 million downloads and over $30 million in annual revenue in under two years – and that the Cal AI team (including Yadegari) had been retained.
According to TechCrunch, what ultimately persuaded MyFitnessPal CEO Mike Fisher to move forward wasn’t just Cal AI’s rapid climb up the app store rankings, but the discipline and focus of the young team behind it.
In an interview, he noted that the founders’ age brought plenty of headlines, and with that, a tendency for some people to underestimate them. But after meeting with the team himself, his view changed:
“You have a conversation with them, like I did late spring last year, and you walk away saying this is an impressive young man.”
A new blueprint for young founders
Perhaps Yadegari and Langmack’s story is a reminder of how much the rules of building a company have changed.
As teenagers, they didn’t need a huge team, a fancy office, or millions in venture funding. With a laptop, off-the-shelf AI tools, and a strong feel for what users actually wanted, they built something people downloaded millions of times.
But what’s just as interesting is how they built it. In an earlier era, founders were told to protect their ideas at all costs. Now, the advantage often comes from doing the opposite – sharing progress, learning in public, and letting the internet become your feedback loop.
Social media, in today’s startup ecosystem, is the concept of distribution, testing, hiring, and brand-building all rolled into one.
There’s also a broader shift happening beneath stories like theirs, with the average breakout AI founder getting younger. Experience still matters, but speed, curiosity, and the ability to adapt quickly are starting to matter more.
When powerful tools are accessible to almost anyone, the edge goes to the people willing to ship fast, listen closely, and improve constantly.
