For the better part of a year, the tech industry has been buzzing about Project Mulberry: Apple's ambitious AI-powered health coaching service. Back in February, reports indicated that these efforts had been scaled back. According to Bloomberg's Mark Gurman, the features are still expected to arrive with iOS 27, though they may not debut until later in the release cycle.
On the other hand, Apple is reportedly going to significantly improve Apple Watch heart-rate tracking with watchOS 27, which could tie in nicely with Apple's eventual AI health coach. This year's watchOS 27 update will focus largely on stability, performance and smaller refinements, rather than introducing major new capabilities. Still, concrete improvements to heart-rate tracking are coming.
Improved heart-rate tracking
Gurman's latest Power On newsletter offers limited details on how exactly Apple Watch heart-rate tracking will be enhanced. However, the announcement signals a long-overdue upgrade to one of the device's core health-monitoring features. Many users and reviewers have noted that while Apple Watch provides generally reliable heart-rate data, it lags behind dedicated fitness trackers like WHOOP in terms of consistency and granularity. WHOOP, for instance, samples heart rate at a much higher frequency throughout the day and night, delivering more detailed insights into recovery, strain, and sleep patterns.
Apple's current implementation typically reads heart rate every few minutes during rest and more frequently during workouts. This can result in gaps that affect the accuracy of daily metrics such as resting heart rate, heart rate variability (HRV), and overall cardiovascular load. With watchOS 27, Apple aims to close that gap by improving both the frequency and precision of readings, potentially using new sensor algorithms or hardware tweaks. The improvement could also lay the groundwork for more advanced features tied to the AI health coach, such as real-time stress detection or personalized workout suggestions based on heart-rate trends.
Beyond sheer data collection, the user interface for heart-rate data has been a popular point of critique. While the Health app aggregates a wealth of information, navigating it can be cumbersome. The iPhone's Health app presents heart-rate trends in line graphs and bar charts, but lacks the contextual insights that competitors like Fitbit or Garmin offer. Apple's upcoming redesign of the Health app, expected in iOS 27, may address these usability issues by providing more intuitive dashboards and smarter notifications.
Project Mulberry delays
We first heard about Project Mulberry around this time last year. It was described as an AI agent that would provide personalized health insights based on Apple Health data, including activity, sleep, nutrition, and vitals. Users would also be able to share their camera feed with the agent, which could offer real-time feedback during workouts—such as correcting posture or suggesting exercise modifications. This feature was initially slated to roll out with a redesigned Health app in iOS 26.4, but was pushed back to iOS 27 while the development team scaled back its ambitions.
Now, it’s sounding like the AI health coach may be delayed even further into the iOS 27 release cycle. Gurman notes, "I don’t expect features from that endeavor to launch until later in the iOS 27 update cycle." This suggests a possible launch with iOS 27.1 in October, or even iOS 27.4 next spring. Apple's decision to hit pause earlier this year stemmed from concerns that its offering wasn't competitive with other health subscriptions on the market, such as those from WHOOP, Oura, or Fitbit Premium. The company wants to take more time to get the product right, potentially integrating deeper machine learning models and more accurate coaching algorithms.
It’s still very likely that the redesigned Health app itself will debut in iOS 27, even if the AI coach arrives later. The redesign is expected to streamline the interface, surface more actionable insights, and better organize the myriad data points Apple Watch collects. The AI health coach would then be made available as part of an Apple Health+ subscription, adding a new revenue stream for Apple's services division. However, with delays, Apple may risk losing early adopters to established competitors.
The health coaching market has become increasingly crowded. WHOOP offers a subscription-based coaching service that analyzes strain and recovery without a display; Oura Ring provides sleep and readiness scores with tips; and Fitbit Premium uses guided programs and health metrics to motivate users. For Apple to stand out, its AI coach needs to be deeply integrated into the ecosystem, leveraging the Apple Watch’s superior sensor suite and the iPhone’s computational power. A camera-based feature could be a differentiator, but it also raises privacy concerns that Apple must address carefully.
Another factor in the delay is leadership changes. In early 2026, Sumbul Desai took over Apple's health group, replacing the previous management. Under her direction, the team reportedly scaled back the initial scope of Project Mulberry, focusing on core features rather than an all-encompassing assistant. This pivot may have set back development timelines, but could ultimately result in a more polished and effective product.
For users who rely on Apple Watch for fitness and health tracking, the improvements to heart-rate monitoring in watchOS 27 will be immediately welcome. Better data quality means more accurate resting heart rate, calories burned, and VO2 max estimates—all of which feed into Apple's Health Sharing and Trends features. The combination of enhanced heart-rate tracking and a redesigned Health app could make iOS 27 and watchOS 27 one of the most significant updates for health enthusiasts in years.
Beyond heart rate, there are expectations that watchOS 27 may also refine sleep tracking and introduce more robust blood oxygen monitoring algorithms. However, Gurman's report focused solely on heart-rate improvements for this cycle. It remains to be seen whether Apple will integrate the enhanced heart-rate data with the delayed AI coach, or if the coach will rely on a broader set of inputs. Given that coaching recommendations often depend on accurate baseline metrics, the timing of these two updates could be complementary.
Apple's long-term vision for health appears to center on proactive wellness rather than passive tracking. With Project Mulberry, the goal is to move from "what happened" to "what should I do next?" The AI coach would analyze trends and suggest changes to diet, exercise, and sleep habits—effectively functioning as a digital personal trainer and nutritionist. If Apple can nail this, it could transform the Apple Watch from a fitness accessory into an essential health companion.
Until then, users can look forward to more reliable heart-rate readings and a smoother Health app experience. The incremental improvements in watchOS 27 are a reminder that Apple often polishes existing features before rolling out major new ones. As with other aspects of the ecosystem, stability and accuracy lay the foundation for advanced intelligence.
Source: 9to5Mac News