Problem

rex.fit addresses the adherence problem in nutrition and fitness tracking: conventional tools demand too much manual input, so users fail to build a durable habit. Its central use case is someone trying to lose weight, gain muscle, or improve long-term health who wants a reliable picture of what they eat without weighing, searching, and logging every meal. The economic value is primarily behavioral: reducing the friction that causes users to abandon tracking and making nutrition coaching more persistent. Rex says more than 20,000 people used its earlier WhatsApp product, but that experience showed the underlying problem was not solved by chat-based logging alone.

Product / Service

The flagship product is The Drop, a wearable AI camera and companion app. Its onboard computer vision identifies when the user is eating, records the meal, and sends a cropped image to the cloud, where AI estimates calories, protein, carbohydrates, and fats. The app then provides nutrition and health feedback, with integrations planned or available for Apple Health and Google Health. The product is sold through a direct preorder model, with the YC launch materials listing a starting price of $199.

rex.fit also operates a lighter-weight software service through WhatsApp: users can send a food photo or text, request workout suggestions, and receive daily reports and personalized feedback. The company’s terms describe Rex Premium as a subscription unlocking unlimited interactions with its AI fitness and nutrition coach, while its site also advertises B2B API solutions for fitness businesses. Together, the wearable, messaging interface, and coaching layer aim to replace manual logging with passive tracking plus actionable guidance.

Market

rex.fit competes at the intersection of consumer health technology, AI nutrition coaching, calorie-tracking apps, and wearable computing. Its closest alternatives include established logging platforms such as MyFitnessPal and Lifesum, as well as newer photo-based AI calorie trackers such as Cal AI. Rex’s differentiation is the attempt to make tracking passive through a dedicated camera wearable rather than requiring users to initiate a log in a mobile app; its WhatsApp coach is a more accessible software-only entry point.

The company is an active YC Winter 2023 startup and has demonstrated early demand rather than remaining purely conceptual. The Drop’s Kickstarter raised $93,288 from 411 backers against an $8,600 goal, and YC reported more than $93,000 in preorders, approximately 450 units, after launch. The product site was still taking preorders in 2026, while Rex’s terms and B2B API offering indicate intended subscription and business monetization. However, the available evidence does not disclose Rex.fit’s own recurring revenue, shipped-unit count, or profitability, so it is best characterized as a commercially launched but revenue-unverified startup rather than confidently labeled either mature or pre-revenue.