In 2021, burnout was the number one health complaint. The Growth Experiment mandated 7-8 hours of sleep tracking and "stress washes" (decompression walks without a phone). Envall famously stated, “You cannot out-train a stressed nervous system.”
Why 108 days? Most fitness challenges run for 4, 6, or at most 8 weeks. Christine Envall deliberately chose 108 days (roughly 15.5 weeks) for a specific physiological reason.
In 2021, the world was still grappling with lockdowns and gym closures. Stress hormones (cortisol) were at an all-time high, and metabolic adaptation (a slowdown in metabolic rate due to prolonged calorie restriction) was rampant. Envall argued that 4-week challenges were too short to change deep-seated habits, and too aggressive for a broken metabolism.
The number 108 also holds spiritual significance in various cultures, representing the wholeness of existence, but for Envall, it represented the number of days required to: Christine Envall The Growth Experiment 108 -2021-
Envall removed the obsession with macro perfection. Instead of demanding that participants hit exact numbers every day, the 2021 experiment utilized a traffic light system (Red, Yellow, Green) for adherence. This allowed for flexibility—essential for mothers and shift workers—without losing the plot entirely.
Although 2021 has passed, the principles of this specific 108-day iteration are timeless. As of 2025, the fitness industry is finally catching up to what Envall preached in 2021: aggressive dieting fails; reverse dieting works; and you cannot hate yourself into a version of yourself you will love.
The "Growth Experiment" is currently being repurposed and updated (there are rumors of a 150-day version), but the 2021 cycle remains the gold standard for those looking to fix damage caused by previous dieting attempts. In 2021, burnout was the number one health complaint
While the 2020 fitness trends were obsessed with tracking macros to the gram, Envall’s 2021 experiment pushed for metabolic flexibility. Participants learned to cycle their carbohydrate and protein intake based on "High Volume Days" versus "Recovery 108s."
Christine Envall is known for her science-based approach to bodybuilding, combining her expertise as a sports nutritionist with her experience as a champion bodybuilder. Her "Growth Experiment" series is a long-running vlog style format documenting her journey to build muscle, manage body composition, and prepare for competitions.
What "Experiment 108" Represents: In Christine’s content library, videos are often numbered sequentially (like a diary entry). "108" indicates the 108th installment of this specific video series. While I cannot provide a verbatim transcript of the specific video, videos from this period (2021) generally focused on the following key areas: One testimonial from a 54-year-old participant read: "I
Those who completed the Christine Envall The Growth Experiment 108 -2021- reported staggering statistics:
One testimonial from a 54-year-old participant read: "I spent 30 years hating my body. Christine’s 2021 experiment taught me that growth isn't about pain. It’s about presence. The 108 minutes became my church."