Analyze and Report on Weight Loss Data

Analyzes weight-loss data across body composition, metabolic rate, energy-deficit tracking, and phase management. Body composition covers BMI (weight in kg divided by height in meters squared) classified against WHO Asian-population thresholds, underweight below 18.5, normal 18.5-24, overweight 24-28, and obese at or above 28; body fat percentage bands for men (15-20% normal, 20-25% elevated, above 25% obese) and women (20-25% normal, 25-30% elevated, above 30% obese); waist circumference and waist-to-hip ratio thresholds for abdominal-obesity risk (men: waist under 90cm/ratio under 0.9 normal; women: waist under 85cm/ratio under 0.85 normal); and ideal weight via the BMI method (height in meters squared times 22) or the corrected Broca method ((height in cm minus 100) times 0.9).

Metabolic rate is computed three ways: the original 1919 Harris-Benedict formula (men: 88.362 + 13.397×weight(kg) + 4.799×height(cm) - 5.677×age; women: 447.593 + 9.247×weight(kg) + 3.098×height(cm) - 4.330×age); the recommended, more accurate Mifflin-St Jeor formula (men: 10×weight(kg) + 6.25×height(cm) - 5×age + 5; women: same minus 161 instead of plus 5); and the lean-mass-based Katch-McArdle formula (370 + 21.6×lean mass(kg), where lean mass is weight times one minus body-fat percentage). TDEE is BMR times an activity factor: 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active, 1.9 extremely active.

Energy-deficit management tracks the daily deficit as TDEE minus actual intake plus exercise burn, compared against a target deficit. Weight-loss estimation uses roughly 7700 kcal per kg of fat, so projected weekly loss is the daily deficit times 7 divided by 7700, with 0.5-1 kg/week (a 500-1000 kcal/day deficit) considered the safe range. Calorie safety floors are 1500 kcal/day for men, 1200 kcal/day for women, and an absolute minimum of BMR times 1.2 regardless of gender.

Phase management covers three stages: the active loss phase, tracking weight change, progress percentage, and loss rate; plateau detection, defined as no meaningful weight change (under 0.5kg fluctuation) for 2+ weeks, with causes named as metabolic adaptation, water retention, or muscle gain, and breakthrough tactics of adjusting calories, changing exercise type, or intermittent fasting; and the maintenance phase, staying within plus-or-minus 2kg of goal weight with regular monitoring and timely plan adjustments.

Reports are generated in a fixed Markdown format for each function: a body-composition report showing current BMI, classification, ideal weight and kg-to-lose; a metabolic-rate report comparing all three BMR formulas side by side with the recommended one starred, the resulting TDEE, a calorie-distribution breakdown (roughly 65% BMR, 20% exercise, 15% NEAT), and three deficit tiers, gentle (500 kcal/day, ~0.5 kg/week), aggressive (750 kcal/day, ~0.75 kg/week), and rapid (1000 kcal/day, ~1 kg/week, flagged as short-term only), each checked against the calorie safety floor; a weekly energy-deficit tracking table with daily intake, exercise burn, NEAT, deficit and pass/fail against target, plus a weekend-dip trend note and next-week targets; and a phase-management report tracking start/current/goal weight, percent progress, recent weekly loss-rate trend, a good/plateau status check, and next-step actions like continuing the current calorie plan or increasing strength-training frequency.

It's invoked through /fitness:weightloss-* and /nutrition:weightloss-* commands, for example /fitness:weightloss-setup --weight 75 --height 175 --age 52 --gender male, /fitness:weightloss-bmr --formula mifflin, /nutrition:weightloss-track --intake 1800 --exercise 350, /fitness:weightloss-report, and /fitness:weightloss-plateau-check. Data is read from data/fitness-tracker.json (weight, body composition, metabolic rate, phase state), data/nutrition-tracker.json (calorie intake, energy deficit, meal plans), and daily logs under data/health-logs/YYYY-MM/YYYY-MM-DD.json.

Safety principles cap recommended intake floors at 1200 kcal/day for women and 1500 kcal/day for men, with an absolute minimum of BMR times 1.2, and cap loss-rate guidance at a safe 0.5-1 kg/week (never above 1.5 kg/week, with 0.5-0.8 kg/week as the sustainable long-term average). The skill states its output is for health reference only, not medical advice, and lists conditions requiring physician consultation first: a BMI above 35, existing chronic disease (heart disease, hypertension, diabetes), prescription medication use, pregnancy or breastfeeding, or any uncertain health condition.

Use it to analyze weight-loss data, metabolic rate, energy deficits, or fat-loss phase management, or when the task involves BMI, body fat, body measurements, BMR/TDEE, or weight-trend analysis. Skip it for a BMI above 35, existing chronic disease, prescription medication use, pregnancy or breastfeeding, or any uncertain health condition, all of which require physician consultation first.

Input is the user's weight, height, age, gender, body-fat percentage, measurements, and logged intake/exercise data. Output is a body-composition report, a metabolic-rate/TDEE report with deficit tiers, a weekly energy-deficit tracking table, and a phase-management report with plateau detection.

Reads and writes data/fitness-tracker.json, data/nutrition-tracker.json, and daily logs under data/health-logs/, invoked through /fitness:weightloss-* and /nutrition:weightloss-* commands.

Anyone tracking their own weight-loss progress who wants BMR/TDEE-based calorie targets, energy-deficit tracking, and plateau-aware phase management, within safe, medically-flagged calorie and loss-rate limits.