A start-to-finish read of every designed OnWeight flow through the Built for Mars lens — the eight core UX-psychology principles, scored, plus what works, what hurts and the fixes that matter most, each grounded in real BFM case studies. The product is already strong and unusually research-led; this audit is written to find the edges, not to restate what it gets right. It is a guide, not gospel — weigh every call against your own user research and the realities of the cut.
This audit has been actioned. Landed in the prototype + All Screens + docs: social proof (paywall + Coach's Read), trial lifeboat with honest pre-charge framing, a 2–3 plan / annual-default paywall offer, the activation reorder (empty dashboard first, opt-in "Sharpen your plan"), a habit reward on the result screen, a one-tap division picker, and the cycle "typical" number alignment. Four recommendations are drafted as future-state sandbox screens (win-back, next-camp-smarter, reminder + widget, coach/peer view). Full record in Logic & Flows §18.8. Open items are business/content calls (trial length + price; replacing labelled placeholders).
Every flow is scored 1–5 against the same eight principles. 1 = violated or absent, 3 = present but unremarkable, 5 = exemplary. Scores are judgement calls against the BFM framework, not measured metrics — treat them as a shared language for the conversation, not a grade.
Where each flow sits across the eight principles. The pattern to notice: OnWeight is excellent at the principles that reduce load and anxiety (Progressive Disclosure, Cognitive Load, Goal Gradient) and consistently thin on one — Social Proof — across every flow. That single column is the biggest systemic opportunity in the product.
Overall the product reads as strong — iterate. The fixes below are sharpening, not rescue: most are about retention beyond a single camp, proof, and the one load-bearing open decision (the trial).
Four patterns recur across the flows — worth deciding at the product level, not flow by flow.
If the team did nothing else, do these, in this order. Ranked by impact on conversion, activation and retention — BFM's house rule is to sequence by user-experience impact, never by build cost.
Companion to OnWeight — Logic & Flows (§10 flows, §9 tracking), the Onboarding & Goal-Setting, Daily Loop and Camp Lifecycle flow maps, and the live screens in All Screens. Framework & case studies: the Built for Mars library (Peter Ramsey) — 48 psychology principles, 90+ case studies, 12 cheatsheets. Cases cited are real BFM teardowns; the mapping to OnWeight is this audit's own. Numbers and verdicts are judgement against that framework, not measured outcomes.