Body Measurements Module

Overview

This module provides a comprehensive set of tools for calculating various body measurements and health-related metrics. It's designed to be easy to use and integrate into your health and fitness applications.

Features

BMI (Body Mass Index) calculation
Body fat percentage estimation
Waist-to-hip ratio calculation
Waist-to-height ratio calculation
BMR (Basal Metabolic Rate) calculation using Harris-Benedict and Mifflin-St Jeor equations
TDEE (Total Daily Energy Expenditure) calculation
Lean body mass calculation
Support for both metric and imperial units
Calorie and weight goal calculations
Estimated weight change calculations

Installation

To use this module, make sure you have "type": "module" in your package.json. This is necessary because the module uses ES6 modules.

Example of `package.json`:

{
  "name": "your-project",
  "version": "1.0.0",
  "type": "module",  // Add this line
  "scripts": {
    "start": "node index.js"
  }
}

To install the Body Measurements module, use npm:

npm install body-measurements

Usage

Here's a basic example of how to use the module:

import { HealthCalculatorFactory } from 'body-measurements'

const user = {
  weight: 70, // kg
  height: 1.75, // meters
  age: 30,
  gender: 'male',
  waist: 80, // cm
  hip: 95, // cm
  neck: 37, // cm
  unitSystem: 'metric',
  activityLevel: 'moderately',
  dailyCalories: 2500,
  weightGoal: 65, // kg
  weeksToWeightGoal: 15,
}

const healthCalculator = HealthCalculatorFactory.createHealthCalculator(user)

// Basic measurements
console.log('BMI:', healthCalculator.getBmi())
console.log('BMI Type:', healthCalculator.getBmiType())
console.log('Body Fat Percentage:', healthCalculator.getBodyFatPercentage())

// Energy calculations
console.log('BMR (Harris-Benedict):', healthCalculator.getBmrHarrisBenedict())
console.log('TDEE (Harris-Benedict):', healthCalculator.getTdeeHarrisBenedict())

// Weight management
console.log(
  'Caloric Surplus/Deficit:',
  healthCalculator.getCaloricSurplusOrDeficit()
)
console.log(
  'Estimated Weekly Weight Change:',
  healthCalculator.getEstimatedWeightChangeWeekly()
)
console.log(
  'Estimated Time to Weight Goal:',
  healthCalculator.getEstimateTimeToWeightGoal()
)

This example demonstrates the basic usage of the module. For more detailed examples, including how to use imperial units and other advanced features, please refer to our GitHub examples page.

Using Imperial Units

To use imperial units, simply change the unitSystem and provide measurements in the appropriate units:

const imperialUser = {
  weight: 154, // lbs
  height: 5.9, // feet
  age: 30,
  gender: 'male',
  waist: 31.5, // inches
  hip: 37.4, // inches
  neck: 14.5, // inches
  unitSystem: 'imperial',
  activityLevel: 'moderately',
  dailyCalories: 2500,
  weightGoal: 143, // lbs
  weeksToWeightGoal: 10,
}

const healthCalculator =
  HealthCalculatorFactory.createHealthCalculator(imperialUser)
// Use the same methods as with metric units

For a complete list of available methods and their descriptions, please refer to the API Documentation section below.

You can find more examples of usage on the projects GitHub page

API Documentation

User Object

The User object provides input data for calculations. It has the following properties:

Property	Type	Description	Required
weight	number	Weight in kg (metric) or lbs (imperial)	No
height	number	Height in meters (metric) or feet (imperial)	No
age	number	Age in years	No
gender	string	'male' or 'female'	No
waist	number	Waist circumference in cm (metric) or inches (imperial)	No
hip	number	Hip circumference in cm (metric) or inches (imperial)	No
neck	number	Neck circumference in cm (metric) or inches (imperial)	No
unitSystem	string	'metric' or 'imperial'	Yes
activityLevel	string	'sedentary', 'lightly', 'moderately', 'very', or 'extremely'	No
dailyCalories	number	Daily calorie intake	No
weightGoal	number	Target weight in kg (metric) or lbs (imperial)	No
weeksToWeightGoal	number	Number of weeks to achieve weight goal	No

HealthCalculator Methods

BMI methods

const user = { weight: 70, height: 1.75, unitSystem: 'metric' }
const healthCalculator = HealthCalculatorFactory.createHealthCalculator(user)

getBmi(): Calculates Body Mass Index (BMI), a measure of body fat based on weight and height. Returns the BMI value, which helps assess whether an individual is underweight, normal weight, overweight, or obese.

console.log(healthCalculator.getBmi())
// Output: 22.857142857142858

getBmiType(): Returns a string with the BMI category based on the calculated BMI value. The possible categories include: 'underweight, severe thinness', 'underweight, moderate thinness', 'underweight, mild thinness', 'normal weight', 'overweight, pre-obese', 'obese, class I', 'obese, class II', or 'obese, class III'. These categories provide a detailed classification of an individual's body weight relative to their height.

console.log(healthCalculator.getBmiType())
// Output: "Normal weight"

getBmiPrime(): Calculates and returns BMI Prime, which is a ratio of the calculated BMI to the upper limit of the normal BMI range (25). This value indicates how close or far an individual is from the normal weight range.

console.log(healthCalculator.getBmiPrime())
// Output: 0.9142857142857143

getIdealWeight(): Returns the ideal weight range in kilograms as an array [min, max] when the BMI type is 'normal weight'. This range is calculated based on height and represents a healthy weight range for the individual according to the BMI classification.

console.log(healthCalculator.getIdealWeight())
// Output: [ 56.65625, 76.25625 ]

Body Composition methods

const user = {
  weight: 70,
  height: 1.75,
  waist: 80,
  gender: 'male',
  neck: 37,
  hip: 100,
  unitSystem: 'metric',
}
const healthCalculator = HealthCalculatorFactory.createHealthCalculator(user)

getWaistToHipRatio(): Calculates the Waist-to-Hip Ratio (WHR), which is used to assess the distribution of body fat and the associated risk of health conditions.

console.log(healthCalculator.getWaistToHipRatio())
// Output: 0.8

getWaistToHeightRatio(): Calculates the Waist-to-Height Ratio (WHtR), a metric used to measure an individual's risk of obesity-related health issues.

console.log(healthCalculator.getWaistToHeightRatio())
// Output: 0.45714285714285713

getBodyFatPercentage(): Estimates body fat percentage based on various measurements such as waist, hip, neck circumference, and weight. This value provides an indication of how much of an individual's total body mass is composed of fat.

console.log(healthCalculator.getBodyFatPercentage())
// Output: 20.149993896363505

getLeanBodyMass(): Calculates lean body mass, using the Boer equation. This represents the weight of everything other than fat (muscles, bones, organs, etc.) and is returned in kilograms.

console.log(healthCalculator.getLeanBodyMass())
// Output: 56.015

BMR methods

const user = {
  weight: 70,
  height: 1.75,
  age: 30,
  gender: 'male',
  unitSystem: 'metric',
}
const healthCalculator = HealthCalculatorFactory.createHealthCalculator(user)

getBmrHarrisBenedict(): Calculates Basal Metabolic Rate (BMR) using the Harris-Benedict equation. Returns the estimated daily calorie requirement to maintain basic bodily functions at rest, such as breathing and circulation.

console.log(healthCalculator.getBmrHarrisBenedict())
// Output: 1695.6670000000001

getBmrMifflinStJeor(): Calculates Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation. Returns the estimated daily calorie requirement to maintain basic bodily functions at rest.

console.log(healthCalculator.getBmrMifflinStJeor())
// Output: 1648.75

TDEE methods

const user = {
  weight: 70,
  height: 1.75,
  age: 30,
  gender: 'male',
  unitSystem: 'metric',
  activityLevel: 'moderately',
}
const healthCalculator = HealthCalculatorFactory.createHealthCalculator(user)

getTdeeHarrisBenedict(): Calculates Total Daily Energy Expenditure (TDEE) using the Harris-Benedict equation, which takes into account BMR and activity level to estimate the total number of calories needed to maintain the current weight.

console.log(healthCalculator.getTdeeHarrisBenedict())
// Output: 2628.2838500000003

getTdeeMifflinStJeor(): Calculates Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation. This calculation estimates the total daily calorie needs based on BMR and physical activity level.

console.log(healthCalculator.getTdeeMifflinStJeor())
// Output: 2555.5625

Calorie based methods

const user = {
  weight: 70,
  height: 1.75,
  age: 30,
  gender: 'male',
  unitSystem: 'metric',
  activityLevel: 'moderately',
  dailyCalories: 2800,
}
const healthCalculator = HealthCalculatorFactory.createHealthCalculator(user)

getCaloricSurplusOrDeficit(): Calculates the daily caloric surplus (if consuming more than needed) or deficit (if consuming less than needed), based on current calorie intake and TDEE. Returns a positive value for surplus or a negative value for deficit.

console.log(healthCalculator.getCaloricSurplusOrDeficit())
// Output: -171.71614999999974

getEstimatedWeightChangeWeekly(): Calculates the estimated weekly weight change based on daily caloric surplus or deficit. This value provides an approximation of how much weight the individual will gain or lose each week.

console.log(healthCalculator.getEstimatedWeightChangeWeekly())
// Output: -0.15610559090909068

getEstimatedWeightChangeMonthly(): Calculates the estimated weekly weight change based on daily caloric surplus or deficit. This value provides an approximation of how much weight the individual will gain or lose each month.

console.log(healthCalculator.getEstimatedWeightChangeMonthly())
// Output: -0.66902396103896

getEstimateTimeToWeightGoal(): Calculates the estimated time (in weeks) to reach the weight goal, based on current weight, caloric intake, and desired weight change. This method provides a timeline for reaching a specific weight target. It returns a number in weeks.

const user = {
  weight: 70,
  height: 1.75,
  age: 30,
  gender: 'male',
  unitSystem: 'metric',
  activityLevel: 'moderately',
  dailyCalories: 2800,
  weightGoal: 65,
}
const healthCalculator = HealthCalculatorFactory.createHealthCalculator(user)
console.log(healthCalculator.getEstimateTimeToWeightGoal())
// Output: 33

getCaloriesForWeightGoal(): Calculates and returns the calories needed to reach the weight goal.

const user = {
  weight: 70,
  height: 1.75,
  age: 30,
  gender: 'male',
  unitSystem: 'metric',
  activityLevel: 'moderately',
  weightGoal: 65,
  weeksToWeightGoal: 12,
}
const healthCalculator = HealthCalculatorFactory.createHealthCalculator(user)
console.log(healthCalculator.getCaloriesForWeightGoal())
// Output: 2170

Method	weight	height	age	gender	waist	hip	neck	unitSystem	activityLevel	dailyCalories	weightGoal	weeksToWeightGoal
getBmi()	X	X						X
getBmiType()	X	X						X
getBmiPrime()	X	X						X
getIdealWeight()		X						X
getWaistToHipRatio()					X	X		X
getWaistToHeightRatio()		X			X			X
getBodyFatPercentage()		X		X	X	X*	X	X
getLeanBodyMass()	X	X		X	X	X*	X	X
getBmrHarrisBenedict()	X	X	X	X				X
getBmrMifflinStJeor()	X	X	X	X				X
getTdeeHarrisBenedict()	X	X	X	X				X	X
getTdeeMifflinStJeor()	X	X	X	X				X	X
getCaloricSurplusOrDeficit()	X	X	X	X				X	X	X
getEstimatedWeightChangeWeekly()	X	X	X	X				X	X	X
getEstimatedWeightChangeMonthly()	X	X	X	X				X	X	X
getEstimateTimeToWeightGoal()	X	X	X	X				X	X	X	X
getCaloriesForWeightGoal()	X	X	X	X				X	X		X	X

*Hip measurement is required for females only when calculating body fat percentage.

Limitations

While this module provides valuable health and fitness calculations, it's important to be aware of its limitations:

BMI Limitations:
- Does not account for age or gender
- Does not differentiate between muscle mass and fat mass
- May not be accurate for athletes, elderly, or individuals with high muscle mass
Body Fat Percentage Estimation:
- Uses the U.S. Navy method, which is an estimation and may not be as accurate as direct measurement methods
- Accuracy may vary depending on individual body composition
BMR and TDEE Calculations:
- Based on equations that use averages and may not account for individual variations in metabolism
- Activity level categories are broad and may not precisely match an individual's actual activity level
General Limitations:
- All calculations are estimates and should not be used as a substitute for professional medical advice
- The module does not account for factors such as genetics, medical conditions, or medications that may affect body composition or metabolism
- Results may be less accurate for individuals at extreme ends of the height or weight spectrum

Always consult with healthcare professionals for personalized health and fitness advice.

Dependencies

This module is designed to have minimal dependencies to ensure easy integration and maintenance. For users of the compiled module, there are no external dependencies required.

Contributing

I welcome contributions to improve the Body Measurements module. Please see our CONTRIBUTING.md file for details on how to contribute.

Changelog

See the CHANGELOG.md for details on version updates.

License

This project is licensed under the ISC License. See the LICENSE file for details.

Support

If you encounter any issues or have questions, please file an issue on our GitHub repository.