# The BMI (Body Mass Index) Program

In 1998, the federal government developed the body mass index (BMI) to determine ideal weights.  Body mass index is calculated as 703 times the weight in pounds divided by the square of the height in inches, the obtained number is then rounded to the nearest whole number (Hint: 23.5 will be rounded to 24; 23.1 will be rounded to 23; 23.52 will be rounded to 24)

BMI Categories:

BMI <19 (underweight)
19≤BMI≤25 (healthy)
25<BMI≤30 (overweight)
BMI is >30 (obese)

Here is a MATLAB program that calculates the BMI of a person, classifies him/her in the BMI category, and then suggests a healthy weight.

It is better to download the program as single quotes in the pasted version do not translate correctly when pasted into a mfile editor of MATLAB.  See the html version for clarity and sample output.

% So you want my phone number and my BMI?  How shallow can you get?

% Worksheet : Finding the BMI of  a person, classifying the BMI and
% suggesting a healthy weight
% Language : Matlab 2007a
% Authors : Autar Kaw
% Last Revised : September 27, 2008

%  Abstract: Finding the body mass index of a person, classifying their health
% and recommending a target weight.

%
%  In 1998, the federal government developed the body mass index (BMI)
%  to determine ideal weights.  Body mass index is calculated as
%  703 times the weight in pounds divided by the square of the height in inches,
%  the obtained number is then rounded to the nearest whole number
%  (23.5 will be rounded to 24; 23.1 will be rounded to 23; 23.52 will be rounded to 24).
%
% Write a MATLAB program to do the following:
%
% Assign a value to weight in lbs, and height in inches and
% then calculate BMI as a rounded integer.
% Output a variable called health_id as
%     0 if the person’s BMI <19 (underweight)
%     1 if the person’s BMI is 19≤BMI≤25 (healthy)
%     2 if the person’s BMI is 25<BMI≤30 (overweight)
%     3 if the person’s BMI is >30 (obese)
% Output also a variable hw for healthy weight in rounded integer lbs for all the conditions.
% Use fprintf command with explanation for the inputs and outputs
clc
clear all
% INPUTS
% Weight in lbs
weight=180;
% Height in inches
height=69;

%REST OF THE PROGRAM
bmi=weight/height^2*703.0;
bmi=round(bmi);

% Assigning the proper health_id and finding the suggested healthy weight
% health_id= BMI category
% hw = healthy weight
% You can use 4 separate if-end statements or switch case statement also.
if (bmi<19)
health_id=0;
hw=19*height^2/703;
elseif (bmi>=19 & bmi<=25);
health_id=1;
elseif (bmi>25 & bmi<=30);
health_id=2;
hw=25*height^2/703;
else
health_id=3;
hw=25*height^2/703;
end
hw=round(hw);

% Printing the outputs
disp(‘The BMI MATLAB program’)
disp(‘Author: Autar K Kaw’)
disp(‘http://numericalmethods.eng.usf.edu&#8217;)
disp(‘September 28, 2008’)
disp(‘ ‘)
fprintf(‘\nWeight of person =%6.0f lbs’,weight)
fprintf(‘\nHeight of person =%6.0f inches’,height)
fprintf(‘\nYour BMI is  =%g ‘,bmi)
if health_id==0
fprintf(‘\nYou are underweight.  \nYour target weight is =%6.0f lbs’,hw)
elseif health_id==1
fprintf(‘\nYou are a healthy weight.  \nYour target weight is =%6.0f lbs’,hw)
elseif health_id==2
fprintf(‘\nYou are overweight.  \nYour target weight is =%6.0f lbs’,hw)
elseif health_id==3
fprintf(‘\nYou are obese.  \nYour target weight is =%6.0f lbs’,hw)
end

________________________________________________________________________________________________

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## Author: Autar Kaw

Autar Kaw (http://autarkaw.com) is a Professor of Mechanical Engineering at the University of South Florida. He has been at USF since 1987, the same year in which he received his Ph. D. in Engineering Mechanics from Clemson University. He is a recipient of the 2012 U.S. Professor of the Year Award. With major funding from NSF, he is the principal and managing contributor in developing the multiple award-winning online open courseware for an undergraduate course in Numerical Methods. The OpenCourseWare (nm.MathForCollege.com) annually receives 1,000,000+ page views, 1,000,000+ views of the YouTube audiovisual lectures, and 150,000+ page views at the NumericalMethodsGuy blog. His current research interests include engineering education research methods, adaptive learning, open courseware, massive open online courses, flipped classrooms, and learning strategies. He has written four textbooks and 80 refereed technical papers, and his opinion editorials have appeared in the St. Petersburg Times and Tampa Tribune.

## One thought on “The BMI (Body Mass Index) Program”

1. Hi,
Thank you very much for the detailed Information for bmi,it’s really helpful.Could you help me to write the codes for saving the Input data and Bmi processed data (name,age,height,weight are the Input data BMI is the output data) from GUI mat-lab to Excel spreadsheet.Thanks in advance.

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