In INSP-RH/bw: Dynamic Body Weight Models for Children and Adults

knitr::opts_chunk$set(echo = TRUE)
knitr::opts_chunk$set(fig.height = 12)
library(ggplot2)
library(bw)

The bw package implements the Dynamic Weight Change model from Hall et al. for adults and the Children dynamic weight model from Hall et al for children.

Installation

To install the latest version please run the following code:

if (!require(devtools)){install.packages("devtools")}
devtools::install_github("INSP-RH/bw", build_vignettes = TRUE)

Adult Model

The main function to estimate weight change is adult_weight. It takes as input body weight (kg), height (m), age (yrs), sex (either "male" or "female") either as column vectors from a database or as individual level. In addition it takes a day-by-day matrix for change in energy intake from baseline (kcal/day) and another matrix for change in sodium (mg/day).

#Individual's parameters
bw  <- 80
ht  <- 1.8
age <- 32
sex <- "female"

#Matrix of energy intake change for 100 days
deltaEI     <- rep(-100, 365)

#Function of sodium intake
deltaNA     <- rep(-10, 365)

#Estimate weight change. 
wtrajectory  <- adult_weight(bw, ht, age, sex, deltaEI, deltaNA)

The variable wtrajectory is a list containing matrices of all the modelled variables:

names(wtrajectory)

These can be plotted with model_plot:

model_plot(wtrajectory)

The model can also be used for computing weight change for several individuals at a time:

#Antropometric data
weights <- c(45, 67, 58, 92, 81)
heights <- c(1.30, 1.73, 1.77, 1.92, 1.73)
ages    <- c(45, 23, 66, 44, 23)
sexes   <- c("male", "female", "female", "male", "male") 

#Matrix of energy consumption reduction: 
EIchange <- rbind(rep(-100, 365), rep(-200, 365), rep(-200, 365), 
                  rep(-123, 365), rep(-50, 365))

#Returns a weight change matrix and other matrices
model_weight <- adult_weight(weights, heights, ages, sexes, 
                             EIchange)

model_plot(model_weight)

Average for included variables can be done:

model_mean(model_weight)

head(model_mean(model_weight))

BMI prevalence can be computed:

adult_bmi(model_weight)

head(adult_bmi(model_weight))

Children Model

The function child_weight estimates weight change the same way as adult_weight. It takes as input age (yrs), sex ("male" or "female"), fat free mass (kg), and fat mass (kg). The functions model_mean and model_plot can be also com A function of energy intake (kcals/yr) for all the years can be inputed.

#Antropometric data
FatFree <- c(32, 17.2, 18.8, 20, 24.1)
Fat     <- c(4.30, 2.02, 3.07, 1.12, 2.93)
ages    <- c(10, 6.2, 5.4, 4, 4.1)
sexes   <- c("male", "female", "female", "male", "male") 

#Returns a weight change matrix and other matrices
model_weight <- child_weight(ages, sexes, Fat, FatFree)

#Plot
model_plot(model_weight)

Mean by sex:

model_mean(model_weight, group = sexes)

head(model_mean(model_weight, group = sexes))

Additional information on usage can be found on the package's vignette:

browseVignettes("bw")

INSP-RH/bw documentation built on July 3, 2023, 6:50 p.m.