What happens to body composition during dieting?

Results: The table shows the correlation between methods

	Auth	UWW	DXA	BIA
Auth		0.657	0.757	0.745
UWW	0.657		0.822	0.834
DXA	0.757	0.822		0.877
BIA	0.745	0.834	0.887

There were 73 subjects with (X±SD) age 42.6±9.9 yrs & BMI=31.7±3.1 kg/m2. Mean group weight loss was 5.4 kg.

This is a wimpy study Doc. Why did you post it? they only lost 5.4 kilograms.

A correlation matrix with r values for fat mass is shown in table. Both clinical methods were significantly correlated with UWW and DXA, with BIA r’s > than Anth. The fraction of weight loss as fat was established for each method by regression: .79 DXA (R2=.83); .77 BIA (.88); .70 UWW (.69); and .57 Anth (.65).

Impedence is better than fat thickness

Results: These results suggest clinical methods, notably BIA, correlate with and provide similar composition of weight loss results to research-based body composition methods.

The Impedance scale was able to correctly tell, how much fat was lost during a diet.

Boring.

Comments and Key points

This is quite a simple and useful poster, presented at a scientific meeting, and reproduced on the Tanita Corporation website¹.

It shows that Bio-Electrical Impedence is better than Fat thickness measurements ( anthropometry) for measuring a persons body fat percentage.

Bio-Electrical Impedance is " Bioimpedance analysis " or BIA. BIA has 83 to 88% correlation with the expensive reference methods of Underwater weighing or Dual-photon X-ray Absorptiometry ( DXA ). That’s pretty good… as good as the correlation between UWW and DXA at 82%.

The Tanita body fat monitor scales use bio electrical impedence methods. The are used in homes, gyms and in scientific research studies.

For a 5.4 kilogram weight loss, about 78% was fat loss, meaning 22% was probably muscle loss. Lets say, 1 kilogram of muscle and 4.4 kilgrams of fat were lost. Ouch.

References

http://www.tanita.com/professional/abstracts/abstract_main.html