Customer Progress Prediction Formulas

Required input data
- Current weight in kg
- Height in cm
- Age in years
- Gender: Male or Female
- Goal: Weight Loss, Weight Gain, Maintain Weight, Muscle Gain, or Fat Loss
- Target weight in kg
- Time period in months
- Activity level

Activity level multipliers
- Sedentary: 1.2
- Lightly Active: 1.375
- Moderately Active: 1.55
- Very Active: 1.725
- Athlete: 1.9

BMR formula: Mifflin-St Jeor
- Male BMR = (10 x weight kg) + (6.25 x height cm) - (5 x age) + 5
- Female BMR = (10 x weight kg) + (6.25 x height cm) - (5 x age) - 161

TDEE formula
- TDEE = BMR x activity multiplier

Goal calorie adjustment
- Weight Loss and Fat Loss use a calorie deficit.
- Weight Gain and Muscle Gain use a calorie surplus.
- Maintain Weight uses no calorie adjustment.
- Required daily calorie change = (required weekly weight change kg x 7700) / 7
- Weight loss deficit is capped at 700 kcal/day for safety.
- Weight gain surplus is capped at 400 kcal/day for safety.
- If the target requires a smaller change than the usual coaching range, the smaller target-driven change is used instead of forcing a larger adjustment.

Weight change estimate
- 1 kg body fat is approximated as 7700 calories.
- Required weekly weight change = abs(current weight - target weight) / available weeks
- Available weeks = time period months x 4.33
- Predicted weekly weight change = (daily calorie adjustment x 7) / 7700
- Predicted future weight = current weight +/- (predicted weekly weight change x week number)
- Predictions are capped at the target weight so they do not overshoot the goal.

Macro formulas
- Protein = current weight kg x protein factor
- Fat grams = (target calories x 0.25) / 9
- Carb grams = (target calories - ((protein grams x 4) + (fat grams x 9))) / 4

Protein factors used
- Weight Loss: 2.0 g/kg
- Fat Loss: 2.0 g/kg
- Muscle Gain: 2.0 g/kg
- Weight Gain: 1.8 g/kg
- Maintain Weight: 1.6 g/kg

Macro calorie values
- Protein: 4 kcal/g
- Carbs: 4 kcal/g
- Fat: 9 kcal/g

Difficulty level
- Easy: required weekly change <= 0.5 kg/week
- Moderate: required weekly change > 0.5 and <= 0.75 kg/week
- Hard: required weekly change > 0.75 and <= 1.0 kg/week
- Extreme / Unsafe: required weekly change > 1.0 kg/week

Additional calculated output
- BMI = weight kg / (height meters x height meters)