blue tape measuring on clear glass square weighing scale
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It is always hard to step on the weight scale. There is the anxiety that comes from not knowing if the sacrifices that were made this week were worth it. And when it is done there is the pleasure or pain of success or failure. But how accurate are the scales that we use to measure weight?

It turns out there is a study for that. But first, what happens when patients are asked about their weight. 


A Norwegian study found that most people were fairly accurate in self-reporting their height and weight. The study was validating the self-reporting of body mass index (BMI) which uses height and weight. However, there was a tendency to under-report weight by the overweight and obese participants. Under-reporting of weight affects the BMI score.

Inaccuracies in reported weights can be ascribed to social desirability, erroneous recall or measurement. It is a common experience to not exactly tell the truth (lie) about weight. So to ensure accuracy in weight, it is best to use a weight scale.

There are two types of scale – dial or digital. A study reported that one in five scales in physician offices may be up to 2.7kg inaccurate.


So another study asked people to bring in their home scales to check precision. Home bathroom scales were accurate in measuring weight. Dial scales were more imprecise that digital scales.As the authors wrote,

“This study suggests that inaccuracies in self-reported weight likely are due in large part to human bias and/or reporting or recall errors and not the home bathroom scales.”

This is a nice way of saying that people lie. It was also found that scales were calibrated infrequently. Recalibrating and re-setting the scales to zero also improves accuracy in measurement. Self-reporting of weight can be accepted from most people. But to be on the safe side get them to step on a scale anyway. 

To learn more about the accuracy of weight,

Skeie, Guri, et al. “Validity of self-reported body mass index among middle-aged participants in the Norwegian Women and Cancer study.” Clinical epidemiology 7 (2015): 313.

Yorkin, Meredith, et al. “Accuracy and consistency of weights provided by home bathroom scales.” BMC public health 13.1 (2013): 11