LA Startup's AI Fitness App Scales to Millions, Sells to MyFitnessPal

Cal AI cofounders grew their lean team and leveraged influencer marketing to rapidly expand their AI-powered calorie tracking app.

Apr. 20, 2026 at 9:11am

Got story updates? Submit your updates here. ›

A highly detailed, glowing 3D macro illustration of a futuristic AI-powered fitness tracker or calorie counting device, illuminated by neon cyan and magenta lights. The device has a sleek, organic shape with recognizable tech elements like sensors, circuits, and displays, conceptually representing the advanced technology powering the Cal AI app's rapid growth and acquisition.An AI-powered fitness tracker glows with the promise of personalized health insights, reflecting the rapid growth and acquisition of the innovative Cal AI app.Los Angeles Today

Jake Castillo, the 31-year-old CMO and cofounder of Cal AI, an AI-powered calorie tracking app based in Los Angeles, shares how his lean team of four quickly scaled the app to millions in monthly revenue through influencer partnerships, leading to its acquisition by MyFitnessPal less than two years after launch. Castillo emphasizes the importance of speed and trusting instincts in the AI era, where execution is everything.

Why it matters

This story highlights how small, nimble teams can leverage AI and influencer marketing to rapidly build and scale a successful tech product, even without significant funding. It provides insights into the "Tiny Teams" era of AI-powered startups and the human skills required to thrive in this environment.

The details

Cal AI launched in April 2024 with a founding team of four. To grow quickly, they focused on influencer marketing, going from one influencer partnership to onboarding 20 per week. They reinvested aggressively into influencer deals, seeing a direct effect on their business. The team tried to avoid bureaucracy, keeping a flat management structure and empowering everyone to be a decision-maker. After less than two years, Cal AI was acquired by MyFitnessPal.

  • Cal AI launched at the end of April 2024.
  • Castillo joined as a cofounder at the beginning of May 2024.
  • The acquisition talks with MyFitnessPal started a while ago and picked up steam around the end of 2025, closing the deal in December 2025.

The players

Jake Castillo

The 31-year-old CMO and cofounder of Cal AI, an AI-powered calorie tracking app based in Los Angeles.

Zach

Castillo's cofounder at Cal AI, known for his confidence in trusting his gut instincts.

Cal AI

An AI-powered calorie tracking app co-founded by a lean team of four in Los Angeles.

MyFitnessPal

The health and fitness app that acquired Cal AI in December 2025.

Got photos? Submit your photos here. ›

What they’re saying

“Imagine holding your breath for two years, and then finally exhaling. That's how I felt when the app I cofounded in 2024 was acquired by MyFitnessPal at the end of last year.”

— Jake Castillo, CMO and Cofounder, Cal AI

“If similar apps are always chasing us, our strategies, and our features, they will keep chasing us if we keep our pace. I think it just comes down to that.”

— Jake Castillo, CMO and Cofounder, Cal AI

“A lot of our decision-making comes down to trusting our gut and intuition, too. That's one thing I definitely want to shout out my cofounder, Zach, for. He's so confident in his gut. If he's got a hunch, he's like, 'Yeah, let's run with it.'”

— Jake Castillo, CMO and Cofounder, Cal AI

What’s next

The MyFitnessPal acquisition has closed, and the Cal AI team is now focused on integrating the app and technology into the larger MyFitnessPal platform to continue scaling the product and user base.

The takeaway

This story demonstrates how small, agile teams can leverage AI and innovative marketing strategies to rapidly build and scale a successful tech product, even without significant funding. It highlights the importance of speed, trusting instincts, and maintaining a lean, high-agency mindset as key factors for thriving in the "Tiny Teams" era of AI-powered startups.