App Overview
Weight PK is an innovative social weight management app that uses gamified PK challenges to help users achieve health goals through friendly competition. The app combines scientific data tracking, social interaction, and motivational mechanisms for effective weight management.

Key Features
Weight Tracking & Management
Daily Recording
• Multiple weight units (kg, lb)
• One-tap quick recording
• Edit and delete history
Data Visualization
• Line charts showing weight trends
• Customizable time ranges
• Multi-user comparison charts
• Goal weight reference line
Goal Management
• Set target weight and duration
• Progress percentage display
• Achievement celebration

PK Challenge System (Core Feature)
Create Challenges
• Custom PK name and type (loss/gain)
• Flexible duration (supports long-term)
• Invite 2-10 friends
Participation & Interaction
• Real-time leaderboard
• View participants' weight changes
• Like and encourage challengers
• PK history review
Data Display
• Trend comparison charts
• Progress statistics
• Final results snapshot

Social Features
Friend System
• Add friends via user ID or email
• Friend request management
• View friend profiles
Message Center
• Friend request notifications
• PK invitation reminders
• System messages
• Read/unread status
Interaction
• Like friends' weight records
• Share achievements

Check-in System
• Daily one-tap check-in
• Consecutive check-in streak
• Check-in calendar
• Achievement badges
• Build healthy habits

Premium Membership
Free
• 90-day weight history
• 1 active PK
• 2-person PK
• Basic charts
Premium
• Full history access
• 10 simultaneous PKs
• 10-person PK
• Ad-free
• Data export
• Exclusive badges & VIP support
Subscription
• Monthly: $4.99/month
• Yearly: $19.99/year (67% savings, 7-day trial)

Data Sync & Security
• Real-time cloud sync (Firebase)
• Multi-device support
• Offline recording
• HTTPS encryption
• Account deletion available

Other Features
Multi-language: Simplified Chinese, English
Notifications: Check-in reminders, PK deadlines, friend updates
Privacy: Control data visibility, online status

App Highlights
Gamified Design: PK challenges, leaderboards, achievements
Social-Driven: Friends supervise, encourage, progress together
Scientific Management: Data visualization, goal tracking, trend analysis
Simple & Easy: Clear interface, one-tap recording, smooth experience

Use Cases
Personal Weight Loss: Set goals, daily tracking, monitor progress
Friend PK: Create challenges, invite friends, compete on leaderboard
Long-term Maintenance: Continue recording, maintain healthy lifestyle

Target Users
• People seeking scientific weight loss
• Fitness enthusiasts
• Those needing external motivation
• Social interaction lovers

Contact & Support
In-app feedback, Help & Feedback page

Weight PK - Make weight loss fun, make sticking to it easy!