Arduino in-body scale

Projects General Guidance
1

This a message from Mina Emad

I'm a pharmacist from Egypt, and I'm seeking a technical consultation

due to increased awareness about the health downfalls of obesity a lot of our customers in the pharmacy where I'm working are asking for body fat measurements using in-body Scale.

as the cost of an in-body scale of a reputable brand are too high for our budget, I opted for building a digital scale using Arduino boards where it can measure both the body weight and height and ask the patients for their age and gender here is a photo of the scale.

IMG_20250108_215621_edit_398667799579791
IMG_20250108_215621_edit_398667799579791759×3361 329 KB

my question is about the use of the equations to drive the body fat percentage from the four parameters from the scale output which are weight, height, age, gender.

here are the equations I'm using.

Body mass index = weight in kg / (height in meters) squared

Body fat percentage = (1.2BMI)+(0.23AGE )-5.4 for males

Body fat percentage = =(1.2BMI)+(0.23AGE)-16.2 for females

Basal metabolic rate = 370+((21.6(1-Fat percentage)weight)

Lean body mass = weight * ((100-fat percentage)/100)

the equations are taken from the following link BMI Calculator

[

BMI Calculator

Free Body Mass Index calculator gives out the BMI value and categorizes BMI based on provided information from W...
](BMI Calculator)

the question now is how accurate is my approach?

and are there any ideas to ameliorate such equation? or even, are there other parameters that can be derived from the same parameters?

2

I think you would need to ask that question in a biology forum.

3

That's a very interesting application and a clever approach to solving the problem of cost.
As long as you can trust that the equations from that site are correct, I don't see a problem with accuracy. Arduino is easily capable to doing the calculations. I assume that you've verified that the scale and height are being measured accurately. Those would be the most concerning issues.

4

BMI is not a reliable measure of health as it is unable to distinguish between fat and muscle, which is why it has pretty much fallen into disrepute. The newest hi-tech scales use different technology but require bare feet to make contact with the electrodes.
I applaud your initiative, but I fear you will cause unneeded anxiety in your customers because the BMI measurement is flawed.
Type the following into the google search field to see all the problems with BMI. The search text is between the [] [is bmi accurate]

5

Maybe, but that's completely orthogonal to what's being asked.

2 Likes
6

I'm really not sure where to ask such questions, and suggestions are welcomed

7

@sonofcy
the role of the BMI here is to calculate the body fat percent , but it's not the main target of the project,essentially the customers are asking for the fat% .
What is more important ,the other technology to measure body fat which require bare foot is called [

Bioelectrical Impedance Analysis

](Bioelectrical Impedance Analysis (BIA))
and it requires a dedicated chip called AD5933 and it can be used with Arduino as you can see here Body Composition Using BIA : 11 Steps - Instructables
but it's not available easily and its circuit is quite complicated for me to use, in addition the technology itself is also does not has the best accuracy. you can see here
What Is Bioelectrical Impedance Analysis and How Accurate Is It?

8

From my research, there is no accurate way to measure body fat without specialist equipment.

However, there a number of ways to get a reasonable estimate, largely involving measuring wight and body dimensions. BMI is a useful rule of thumb. All of the easy ways a person could do themself, and the better ways need special equipment.

Tbh, I don't think people need a definite number, it's not like something suddenly happens if body fat exceeds an arbitrary number. Also I doubt many body-builders are going to the pharmacy to get their body fat checked.

9

We've had a Tanita bodyfat scale for quite a while now. I'm guessing that's similar to what most athletes are using. It uses the technology that @sonofcy mentioned. I don't know what they cost: we got it back when my wife worked for a medical supply distributor and used her employee discount.

10

I have Withings, cheapest model I think. They range from about $110 to $365. They are quite impressive, but you need to be barefoot.
I will take a measurement later today and report the numbers on my scale. We can then use @drmina2023 formulas to see what the difference is.

11

@bobcousins
here in Egypt, It's common practice for ordinary people to measure their body fat in the pharmacy.
so, how do you find my approach?

12

I didn't say that. I said I don't expect bodybuilders (who might have a non-typical muscle mass), to be going to a pharmacy. For an average Joe or Jane, sure.

But if you are not going to read what I write, there is no point in me writing further.

13

@sonofcy
regarding the cost, here is the scale I would like to replicate

459845045_1075453327920867_2425428782531134693_n
459845045_1075453327920867_2425428782531134693_n750×1500 108 KB

it measures the height, in addition to the body fat and it's cost starts from 1000 US dollars up to 4000 dollars which is a huge cost, my project budget was about 100 dollars,
additionally, my scale can be used to measure weight only or height only plus calculating the body fat when needed, which is not the case with the high end version which measures all the parameters at once.

14

@bobcousins
Sorry for the misunderstanding ,please accept my apology.
you opinions are always of a value for me

16

I've already built the project and it costed about 100 dollars

17

That's a bit rude, don't you think? OP is in Egypt.

18

Please accept my apology, honestly I am not really sure what is the problem with my answer?

19

Sorry, maybe, I am on the spectrum so sometimes don't understand that. I will remove.

20

Your answer is fine @drmina2023 . I was responding to someone else.

22

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.