With the launch of Fitbit's latest devices, the "Fitbit by Google" branding was introduced. The Sense 2 and Versa 4 already have a user UI designed according to Wear OS 3, but the integration becomes even deeper from 2023 onwards, when Google Accounts will be required to use Fitbit.
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For now, “Fitbit continues to provide its products and services separately from Google” and a Fitbit account is required to use the app and devices (smartwatches, fitness trackers, and scales).
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However, Fitbit will "allow Fitbit to be used with a Google account sometime in 2023.".
Google accounts on Fitbit will support a range of benefits for Fitbit users, including a single sign-on for Fitbit and other Google services, industry-leading account security, centralized privacy controls for Fitbit user data, and more features from Google on Fitbit.
There are many benefits touted, with security being notable for something as sensitive as health and fitness. Fitbit currently maintains its own two-factor authentication (2FA) login system that is done via SMS. There is already a Google login option, and Fitbit removed its Facebook last year.
However, this change involves more than just the login process and unification into a set of credentials.

After next year's change, "some uses of Fitbit will require a Google account, including signing up for Fitbit or activating recently released Fitbit devices and features." The latter is notable in the context of Fitbit working on a premium Wear OS 3 watch. New customers will have to use a Google Account starting next year, while gating features to the new backend is similar to the Nest app/account transition to Google Home.
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Once the change is made, there will be an “option to move Fitbit to your Google account,” while existing users can continue to use their Fitbit account “until at least early 2025.” However, again, those users won’t be able to use new devices or health features until they migrate.
Sometime in 2025, "a Google account will be required to use Fitbit." More details coming next year:
We will be transparent with our customers about the timeline for terminating Fitbit accounts through notifications within the Fitbit app, via email, and in help articles.
Google will abide by the “binding commitments” it made with global regulators to complete the acquisition. This includes ensuring that Fitbit users’ health and wellness data will not be used for Google Ads.
Information source: 9to5google.com
