BACKGROUND/AIMS:Recently classified as an epidemic by the WHO, obesity (as well as the state of being overweight) clearly affects significant populations across all ages. The relationship between obesity and some diseases (e.g. cardiovascular ones) is known, although many paradoxes remain to be explained. Very little information is available, however, regarding its impact on skin physiology and skin disease. This study aims to examine the influence of excessive weight on epidermal hydration and transepidermal water loss, key variables of skin water balance and skin biomechanics.METHODS:A convenience sample of 89 healthy female volunteers was selected and divided into 4 groups, according to their BMI (body mass index), as normal (control), overweight, obese (I and II), and morbid. Skin physiology was quantitatively assessed in all individuals in 4 anatomical areas using non-invasive biometrical analysis by reference instrumentation. Descriptive and comparative statistics were applied, adopting a confidence level of 95%.RESULTS:A non-linear alteration for all variables was detected as a function of BMI.CONCLUSION:Results suggest that excessive weight might favour skin performance within certain limits, reflecting a particular adaptation of the skin to the weight gain and body contour.

The Stratum corneum is a principal protector against physical, chemical, biological aggression and water loss in human skin. The repeated use of alcohol-based hand sanitizers might result in dryness and aggression. This study aims to evaluate the impact of a four week-long regular use of an alcohol-based gel hand sanitizer on skin hydration on the epidermal ‘barrier’ function using a kinetic model to quantify TEWL desorption curves following a POST test. A group of 13 female (19.7 ± 1.0 years old) washed one of their hands for 29 consecutive days with a commercially available ethanol-based gel sanitizer. TEWL, superficial hydration (SH) and deep hydration (DH) were measured on days 1, 8, 15, 22 and 29, while a continuous TEWL recording following a 24 hour POST was made on days 1, 15 and 29 on a second skin area. No differences were found for the control hand throughout the study. For the test hand an increase of TEWL was found between days 1 and 8, as well as an increase of SH and DH between days 1 and 22. No significant differences were found for the kinetic parameters. These results suggest that the frequent use of the sanitizer gel might alter the skin barrier function.

The various studies on the importance of water in the hydration of human skin have suggested that an increased dietary intake might positively impact the physiology of normal skin. We evaluated the consequences of increasing water intake through drinking in skin hydration in vivo. Eating habits were maintained, evaluated by a Food Frequency Questionnaire and based on total water consumption. In two groups with different total water consumption, we evaluated the impact of 2L/day water after 30 days,. This increase produced no hemodynamic changes or weight changes but an improvement in the epidermal hydration was suggested. The magnitude of the impact on skin hydration was higher in the group that regularly consumed less water, suggesting that the increase in water consumption has more beneficial effects on those individuals who habitually consume less water per day. These data are consistent with the published literature, justifying interest in looking further into this topic, in order to better understand the importance of dietary water in the context of cutaneous physiology, especially in the group of subjects with reduced consumption habits.

In recent years cutaneous circulation has emerged as an interesting window through which to study microcirculatory function and dysfunction mechanisms. Non-invasive technologies, including Laser Doppler Flowmetry (LDF), transcutaneous gasimetry and Transepidermal Water Loss (TEWL), helped to consider cutaneous circulation as a useful translational model in vascular disease. In this study we attempted to evaluate the response profile from a group of healthy young individuals (n=8), of both genders (24,5 ± 0,8 years old) to three perfusion-conditioning maneuvers in the lower limb - A: leg elevation while seated; B: leg elevation during dorsal decubitus; C: supra-systolic occlusion with a tourniquet-cuff. Measurement techniques included LDF, transcutaneous (tc) pO2 and pCO2 partial pressures, by gasimetry and TEWL by evaporimetry. Descriptive and nonparametric statistics were applied and a 95% confidence level adopted. tcpO2 and tcpCO2 changed significantly during the maneuvers. A reciprocal evolution profile was registered in LDF and TEWL in A and C which might suggest that under the present experimental conditions local perfusion might influence the epidermal “barrier” function. The proposed models seem to be appropriate to characterize the peripheral microcirculation in vivo, justifying further development studies.

Obesity is an increasing public health issue, particularly in Portugal, where more than 50% of the population is obese. The pathophysiological consequences of being overweight have a severe cutaneous impact. However, there is still a lack of studies to link these alterations to BMI categories. This present work intends to identify the hydration and biomechanical behaviour changes related to weight augmentation. This transversal study was performed on a convenience sample of 57 volunteers, all females, aged between 20 and 46 (30±8) years old. Volunteers were divided in two groups – group I, with a BMI between 19,9 and 24,9 Kg/m2 and group II, between 25 and 29,9 Kg/m2. One single determination of the superficial hydration, transepidermal water loss and biomechanical behaviour of the skin, was obtained with non-invasive methods. The data showed that weight increase positively influences hydration levels and transepidermal water loss, and negatively influences the skin's biomechanical behaviour. Despite the relevance of these results, there is still a need for complementary studies, with a wider number of individuals, in order to better understand its nature and meaning.

The impact of obesity in the pathophysiology of human skin seems to be related to various dermatoses, basically resulting from the change in its normal physiology, including changes in the “barrier” and the “envelope" functions as well . However, the available information is still scarce due to the many complexities of the subject. This work aims to define an experimental methodology approach to objectively study the functional changes that characterize the obese skin. This transversal study included 28 healthy volunteers, female (mean age 23 ± 5 years old), after informed consent. Skin functional characterization was obtained in one single measurement by non-invasive techniques, under controlled conditions. Relevant variables were hydration (superficial and deep), barrier function and biomechanical behavior, measured at four different anatomical areas. Through the SPSS (v 20.0) a univariate statistical analysis was performed to calculate central tendency and dispersion measures. The Pearson's and the Spearman's tests were chosen for those variables that followed , or not, a normal distribution, respectively, assuming a confidence level of 95%. Results allow us to propose a methodology for the study of the skin applied to obese patients, including the choice of the anatomical areas and variables appropriate to the intended goal.

Several studies about the importance of water in the hydration of the human skin suggest that higher water intake might have a positive impact on the skin. When measuring water consumption, it must be taken into account that the water comes from various sources. With this in mind, we evaluated the impact of an increased inflow of 2L of water per day, on two groups with different daily water intakes. Results suggest that there is an improvement in the epidermal and dermal hydration obtained by standard methods. The magnitude of this impact on skin hydration is greater in the group that regularly consumes less water. This suggests that an increase in water consumption has more beneficial effects on the skin health of those individuals that consume less water per day. These data are consistent with the published literature, which therefore justifies further research into this topic.

Bioimpedance seems to be particularly suited to the non-invasive measurement of several physiological variables. The present study aimed to ascertain whether the quantification of total body water and intracellular and extracellular fluid compartments, obtained through a bioimpedance-based analytical device, could be correlated with the concentration sodium, potassium and chloride ions, obtained from venous blood ionogram. Volunteers of both genders, of various ages and with various health conditions were studied. None of the volunteers suffered from any hydro-electrolytic disorder. Body water measurements were obtained by a Bodystat® QuadScan 4000 and ionogram obtained through potentiometry. Under the present experimental conditions, which should be considered merely a preliminary approach to the questions raised, no relations were established between the variables under study. However, the method´s potential interest and its practicability justifies further investigation. This would include increasing the number of patients studied and refining the methodology used.