https://slt.co/Products/BodyVoltageKits/HomeTestKit.aspxIt seems that a body voltage meter should be a true RMS meter.

https://www.fluke.com/en-us/learn/blog/electrical/what-is-true-rms says

"RMS = root mean square. Though its formula can be challenging to grasp, RMS essentially calculates the equivalent direct current (dc) value of an ac waveform. More technically, it determines the "effective," or dc heating value, of any ac wave shape.

An average-responding meter uses averaging mathematical formulas to accurately measure pure sinusoidal waves. It can measure non-sinusoidal waves, but with uncertain accuracy.

A more sophisticated true-RMS meter can accurately measure both pure waves and the more complex non-sinusoidal waves. Waveforms can be distorted by nonlinear loads such as variable speed drives or computers. An averaging meter attempting to measure distorted waves can be up to 40% low or 10% high in its calculations."

I think a human body hosts distorted waves.