From Invisible to Integrated: How Metabolic Fitness Built a Retention Program That Actually Knows Its Members
Metabolic Fitness was running email marketing with no visibility into member behavior — class bookings, cancellations, memberships, and attendance were invisible to their retention program. Here's how Zettler Digital migrated them from Mailchimp to Klaviyo and connected Mindbody to change that.
A Fitness Brand Built on Community. A Retention Program That Didn't Know Its Members.
Founded in 2012 out of a converted truck-stop diner in upstate New York, Metabolic Fitness has grown into a multi-location group fitness brand built around 45-minute strength training sessions that work for every age, fitness level, and goal. What sets Metabolic apart isn't just the workout — it's the community. Members don't just show up to class; they show up for each other.
That community deserved a retention program to match.
A Retention Program Flying Blind
Metabolic was running email marketing through Mailchimp — but their member management lived inside Mindbody, the software powering class bookings, membership billing, and studio operations across every location.
The two systems didn't talk to each other.
That meant class bookings, cancellations, membership starts, trial expirations, and attendance patterns were completely invisible to their email program. Every send was a batch blast to the full list with no knowledge of where a member was in their journey — whether they'd just booked their first class, hadn't shown up in three weeks, or were days away from canceling.
For a brand whose entire value proposition is personal, community-driven fitness, that disconnect was costing them.
Building the Infrastructure First
The engagement started with a full migration from Mailchimp to Klaviyo — the platform built for exactly this kind of data-connected retention marketing.
Platform migration
Zettler Digital managed the complete move from Mailchimp to Klaviyo, preserving list history and establishing a clean, properly structured account from day one.
List cleaning and deliverability setup
Before a single campaign went out, the list was cleaned and the sending infrastructure was configured for maximum inbox placement — proper authentication, suppression hygiene, and a thoughtful warm-up approach.
Mindbody integration
This was the unlock. By connecting Klaviyo directly to Mindbody, Metabolic's email program can now see what their members are actually doing: when someone books a class, cancels a membership, completes a trial, or goes quiet. For the first time, the retention program has the same view of a member that a coach on the floor does.
Campaign execution
With the foundation in place, Zettler Digital began executing campaigns to Metabolic's engaged list — putting the new infrastructure to work immediately while the automation layer is built out.
The Foundation Is Working
Doing the migration and integration work correctly from the start shows up immediately. Within the first 30 days on Klaviyo, Metabolic's email program is hitting every deliverability benchmark — inbox placement is strong, the audience is engaged, and there isn't a spam complaint in sight. The program has a real foundation to build on.
CEO, Metabolic Fitness
What's Next
With Mindbody now feeding real behavioral data into Klaviyo, Metabolic is positioned to build automations that mirror the attentiveness of their in-studio coaching staff: welcoming new members, re-engaging members who've gone quiet, converting trial members before they lapse, and reinforcing the community between classes.
The infrastructure is live. The results are already showing. The retention engine is just getting started.
