Weight-Loss Analysis Skill

Analyze weight-loss data, calculate metabolic rate, track energy deficit, and manage weight-loss phases.

Functions

1. Body-composition analysis

BMI calculation and classification

• BMI = weight(kg) / height(m)²
• Classification (WHO Asian criteria):
• Underweight: BMI < 18.5
• Normal: 18.5 ≤ BMI < 24
• Overweight: 24 ≤ BMI < 28
• Obese: BMI ≥ 28

Body-fat percentage assessment

• Men: 15-20% (normal), 20-25% (high), >25% (obese)
• Women: 20-25% (normal), 25-30% (high), >30% (obese)

Circumference analysis

• Waist assessment
• Men: < 90cm (normal), ≥ 90cm (abdominal obesity)
• Women: < 85cm (normal), ≥ 85cm (abdominal obesity)
• Waist-to-hip ratio
• Men: < 0.9 (normal), ≥ 0.9 (abdominal obesity)
• Women: < 0.85 (normal), ≥ 0.85 (abdominal obesity)

Ideal-weight calculation

• BMI method: ideal weight = height(m)² × 22
• Broca method (adjusted): ideal weight = (height cm - 100) × 0.9

2. Metabolic-rate calculation

Harris-Benedict equation (original 1919)

• Men: BMR = 88.362 + (13.397 × weight kg) + (4.799 × height cm) - (5.677 × age)
• Women: BMR = 447.593 + (9.247 × weight kg) + (3.098 × height cm) - (4.330 × age)

Mifflin-St Jeor equation (recommended, more accurate)

• Men: BMR = (10 × weight kg) + (6.25 × height cm) - (5 × age) + 5
• Women: BMR = (10 × weight kg) + (6.25 × height cm) - (5 × age) - 161

Katch-McArdle equation (based on lean body mass)

• BMR = 370 + (21.6 × lean body mass kg)
• Lean body mass = weight kg × (1 - body-fat %)

TDEE calculation

• TDEE = BMR × activity factor
• Activity factors:
• Sedentary: 1.2
• Lightly active: 1.375
• Moderately active: 1.55
• Highly active: 1.725
• Extremely active: 1.9

3. Energy-deficit management

Daily energy-deficit tracking

• Deficit = TDEE - actual intake + exercise burn
• Target analysis: actual deficit vs. target deficit

Weight-loss estimation

• 1 kg of fat ≈ 7700 kcal
• Estimated weekly loss = daily deficit × 7 / 7700
• Safe rate of loss: 0.5-1 kg/week (deficit 500-1000 kcal/day)

Calorie safety floor

• Minimum for men: 1500 kcal/day
• Minimum for women: 1200 kcal/day
• Absolute minimum: BMR × 1.2

4. Phase management

Weight-loss phase

• Track weight change
• Compute weight-loss progress
• Monitor rate of loss

Plateau detection

• Definition: no clear weight change for >2 weeks (fluctuation <0.5 kg)
• Possible causes: metabolic adaptation, water retention, muscle gain
• Breakthrough methods: adjust calories, change exercise, intermittent fasting

Maintenance phase

• Within ±2 kg of target weight
• Monitor weight regularly
• Adjust the plan promptly

Data Sources

Primary data sources

1. Fitness tracker

• Path: data/fitness-tracker.json
• Content: weight records, body composition, metabolic rate, phase management

1. Nutrition tracker

• Path: data/nutrition-tracker.json
• Content: calorie intake, energy deficit, meal plan

1. Health logs

• Path: data/health-logs/YYYY-MM/YYYY-MM-DD.json
• Content: daily weight, food records

Output Format

Body-composition analysis report

# Body-Composition Analysis Report

## Basic information
- Sex: Male
- Age: 52
- Height: 175cm
- Weight: 75kg

## Body metrics

### BMI
- Current BMI: 24.5
- Classification: overweight
- Ideal weight: 67kg (BMI=22)
- Weight to lose: 8kg

### Body-fat percentage
- Current body fat: 25%
- Classification: high
- Target body fat: 15-20%

### Circumference analysis
- Waist: 92cm (abdominal-obesity risk)
- Hip: 98cm
- Waist-to-hip ratio: 0.94 (abdominal obesity)

## Suggestions
1. Lose 0.5-1 kg per week
2. Target time frame: 8-16 weeks
3. Combined intervention: diet + exercise

Metabolic-rate analysis report

# Metabolic-Rate Analysis Report

## BMR calculation

| Equation | BMR | Notes |
|----------|-----|-------|
| Harris-Benedict | 1650 | original 1919 formula |
| Mifflin-St Jeor | 1620 | recommended ⭐ |
| Katch-McArdle | 1700 | based on body-fat % |

**Recommended BMR: 1620 kcal/day**

## TDEE calculation

- Activity level: moderate exercise
- Activity factor: 1.55
- TDEE: 1620 × 1.55 = **2511 kcal/day**

### Calorie breakdown
- BMR (basal metabolism): 65% ≈ 1632 kcal
- Exercise burn: 20% ≈ 502 kcal
- NEAT (daily activity): 15% ≈ 377 kcal

## Weight-loss calorie targets

### Gentle plan
- Daily deficit: 500 kcal
- Target intake: 2011 kcal/day
- Estimated loss: 0.5 kg/week

### Aggressive plan
- Daily deficit: 750 kcal
- Target intake: 1761 kcal/day
- Estimated loss: 0.75 kg/week

### Rapid plan
- Daily deficit: 1000 kcal
- Target intake: 1511 kcal/day
- Estimated loss: 1 kg/week
- ⚠️ Short-term use only

## Safety check
- Minimum calorie requirement: 1500 kcal/day (men)
- Rapid-plan calories: 1511 kcal/day ✅
- Recommended: gentle or aggressive plan

Energy-deficit tracking report

# Energy-Deficit Tracking Report

## Weekly summary (2025-06-16 to 2025-06-22)

| Day | Intake | Exercise burn | NEAT | Deficit | Met target |
|-----|--------|---------------|------|---------|------------|
| Mon | 1800 | 350 | 300 | 961 | ✅ |
| Tue | 2100 | 200 | 250 | 461 | ❌ |
| Wed | 1750 | 400 | 300 | 1061 | ✅ |
| Thu | 1950 | 300 | 280 | 741 | ✅ |
| Fri | 2200 | 150 | 200 | 261 | ❌ |
| Sat | 2400 | 100 | 150 | -89 | ❌ |
| Sun | 1850 | 350 | 300 | 911 | ✅ |

**Target deficit: 500 kcal/day**

## Statistical analysis
- Average deficit: 642 kcal/day
- Days on target: 5/7 (71%)
- Total deficit: 4494 kcal
- Estimated loss: 0.58 kg

## Trend analysis
- Weekend deficits are smaller (more social activity)
- Suggestion: plan weekend meals in advance

## Next week's goals
- Days on target: 7/7
- Average deficit: 700 kcal/day
- Estimated loss: 0.64 kg

Phase-management report

# Weight-Loss Phase-Management Report

## Current phase: weight-loss

### Progress tracking
- Start date: 2025-01-01
- Initial weight: 82kg
- Current weight: 75kg
- Target weight: 67kg
- Lost so far: 7kg
- Remaining: 8kg
- Progress: 47%

### Rate of loss
- Total weeks: 24
- Average loss: 0.29 kg/week
- Last 4 weeks: 0.35 kg/week ⬆️ accelerating

## Status analysis

### Current status: ✅ good
- Rate of loss is in the healthy range (0.5-1 kg/week)
- Stable metabolic rate
- Muscle mass well maintained

### Plateau monitoring
- Last 2 weeks' change: -0.8 kg
- Status: ❌ not a plateau

## Next steps
1. Continue the current calorie plan
2. Increase strength-training frequency
3. Monitor body composition weekly

How to Use

Invoke via /fitness:weightloss-* and /nutrition:weightloss-* commands.

Example commands

# Set up a weight-loss plan
/fitness:weightloss-setup --weight 75 --height 175 --age 52 --gender male

# Calculate metabolic rate
/fitness:weightloss-bmr --formula mifflin

# Track energy deficit
/nutrition:weightloss-track --intake 1800 --exercise 350

# Generate a phase report
/fitness:weightloss-report

# Detect a plateau
/fitness:weightloss-plateau-check

Safety Principles

Calorie safety floor

• Not recommended below 1200 kcal/day (women)
• Not recommended below 1500 kcal/day (men)
• Absolute minimum no lower than BMR × 1.2

Rate-of-loss control

• Safe range: 0.5-1 kg/week
• Maximum: 1.5 kg/week
• Long-term average: 0.5-0.8 kg/week

Medical Disclaimer

This skill is for health reference only and does not constitute medical advice.

Consult a physician in the following cases:

• BMI > 35
• Chronic conditions such as heart disease, hypertension, or diabetes
• Taking prescription medication
• Pregnant or breastfeeding
• Any uncertain health condition

Skill version: v1.0 Last updated: 2026-01-14 Maintainer: MedClawMini