Plantar Callosities and the Validity of Body Composition Assessment by Bio-impedance in Severely Obese Persons

As the prevalence of obesity continues to increase, many parts of the world are progressively facing a rise in the number of people who fall under WHO obesity class 2 and 3. Since severe obesity is characterized by large alterations in body compartments when compared to overweight or non-obese individuals, there is a need for the evaluation of the body composition of severely obese persons. There is very few published research available on what methods of body composition measurements can be used on this population.

Other studies have also shown the tendency of bioelectrical impedance analysis (BIA) instruments to underestimate percentage of fat mass and overestimate the percentage of fat free nass, compared with gold-standard techniques. We think that plantar callosities might have contributed to the lack of accurate measurements. Thus, the primary aim of this study is to determine whether plantar callosities influence the validity of body composition measurements obtained by BIA, using the InBody 720. The secondary aim is to assess the validity of the body composition measurements obtained by BIA (InBody 720) in severely obese individuals, using air-displacement plethysmography (BodPod) as the gold standard. Additionally, we will explore various sources of error using test-retest reliabilities by measuring body composition with different arm postures. We will examine this further to rule out the possibility of "positions of measurement" as a potential confounder of this study.

Inclusion criteria

• Adults (18-50 years old)
• class 2 and 3 obesity (BMI > 35 kg/m2)
• moderate to severe callosities

Exclusion criteria

• Intractable plantar keratosis (IPK), which are painful plantar calluses located under the metatarsal heads.
• pregnancy
• menopause
• diseases that cause water retention (edema, renal insufficiency, hypertension, etc.)