BMI tracking

BMI is already logged. Just add your current weight and the BMI is calculated and put into the weight graph. You can switch between showing weight and BMI.

I don’t think you understood my question. 

Possibly. Why not tell me/us what you want to log?

BMI is a well defined formula and is calculated automatically. Do you want log your own modified BMI values?

Yes,I wish there was a way to log my own bmi. The calculated bmi is about 8-10% off of where I actually am. I’m more of a weight lifter than runner… and as I said before, i can’t justify another $150 on a smart scale. 

You don't need a smart scale to log your weight. Just write your weight. Done. BMI is calculated for you. BMI is BMI. If you want to use some other formula then it isn't BMI.
You can use the current calculated BMI and use it as a reference value and see how it changes with your weight.

If you want to adjust the BMI value you can adjust your length to get the value you want.

What are you using BMI for in your training?

e7andy said:

BMI is BMI

Exactly, more on BMI here:

en.wikipedia.org/.../Body_mass_index

CMA-CPH said:

Exactly, more on BMI here:

en.wikipedia.org/.../Body_mass_index

That article CMA-CPH posted, shows the formula for BMI, and it is exactly what Garmin uses when you enter the weight. BMI is only one, there is no "my own BMI", It is always the same value based on the height and the weight:

8236660 probably mistakes BMI for the Body Fat%, which can be indeed variable, and not directly derived from the weight. You can track that too, but you either have to use a Garmin Index scale, or have to import the Body Fat% manually.

My mistake, I was mistakenly using bmi and body fat % interchangeably. Thanks for catching and clarifying that. 

I'll have to take a look again, I don’t recall seeing body fat% anywhere in the app or on the desktop version. 

As I wrote, you can only add Body Fat% with an Index scale, or importing it. There is no entry form for that value in the app. Have a look also here: Add body fat % to Garmin Connect?