[Олег1099]

Discussion


To the best of our knowledge, this paper presents for the first time daily hemodynamic, metabolic, renal, and anthropometric data during FWD. The described anthropometric parameters can be measured quickly, reliably, and reproducibly, since they refer to definite lines and points of the body. The laboratory measurements are simple and cost-effective and can be performed in conventional diagnostic laboratory units. Therefore, monitoring of FWD participants is an easy procedure for physicians without requiring support of advanced equipment.

5 days of FWD contain a triple risk: hypovolemia, hypertonicity, and hypoglycemia. However, our participants have tolerated the dry fasting well and none of them showed hypotension or any noteworthy disorder in HR, SatO2, electrolyte concentration, serum osmolality, and glucose level. It seems that a potent hormonal and nervous contra-regulation results in the effective management of FWD risks.

There is no definite explanation for the temporary K+ increase on day 2. However, no complaints were reported and no heart rhythm changes were registered by any of the participants. Serum glucose decrease on days 1-3 could be attributed to the interruption of food supply, whereas its increase on days 4-5 is probably a result of hormonal contra-regulation.

The mechanism of increased creatinine clearance during FWD could not yet be explained. However, the reported positive association between urine osmolality and GFR and negative association between 24-hour urine volume and GFR [8,9] are consistent with our findings of decreased urine volume and increased serum osmolality along with GFR increase. We hypothesize that the increasing values of serum osmolality may play a role in the mechanisms of edema mobilization and generalized volume reduction, since they create an increasing osmotic gradient between tissue fluid and blood. This facilitates extra tissue water to be passed to the blood. Extra tissue water from renal parenchyma could also be passed to the blood resulting in decongestion of kidney tissues, improvement of renal microcirculation, and increase of GFR. Furthermore, increasing serum osmolality may cause a gradual declining of the water content of the intestinal walls and lumen, thus decreasing abdominal volume and taking effect on the intestinal flora.

With weight loss of 1,390 ± 60 g/day, FWD seems to be the most effective dietary protocol, since the magnitude of weight reduction is 50-100% more than observed during juice or water fasting [3,31]. It has to be further investigated whether the impressive weight loss and the remarkable reduction of body circumferences during FWD have any impact on disease risks.

Among the 6 circumferences measured in this study, WC changed most dramatically. The total decrease in WC during FWD corresponds to a huge decrease of the abdominal volume within 5 days. Such a massive and rapid volume decrease can hardly be attributed to the reduction of visceral fat. In view of the total weight loss, urine discharge, and the additional insensible water loss, this volume decrease could be mainly attributed to elimination of edema fluids from the abdominal organs. According to these results, the terms ‘visceral fat', ‘central obesity', and ‘abdominal obesity' or ‘adiposity' used in various reports [16,18,20,21,23,32] may need reconsideration. The risks related to increased WC might be related rather to the edema than to the fat tissue of the abdominal organs. On the other hand, the decrease in NC reflects a considerable volume reduction for such a small part of the body. Removal of muscle spasms in this region could be a conceivable mechanism for this NC reduction. HC and HCO can be seen as volume change detectors for the hip region. HCO is additionally a unique volume change indicator for the lower abdomen and, in this sense, complements the findings on WC in evaluating any changes of the abdominal volume. Consequently, the decreases of HC and HCO reflect a volume reduction in the hip region and lower abdomen during FWD. The CCA and CCN are detectors of thoracic volume changes. Their reduction may result from of the declining of the lung volume. Further research is required to determine any association between this reduction and an increase of the forced expiratory volumes FEV and FEV1, as described with regard to reduction of WC [19,30].

The new quotients QNC, QCCA, QCCN, QWC, QHC, and QHCO quantify the capability of a weight decreasing method to reduce the volume-related circumferences. They provide an indispensable tool for monitoring the correspondence of body weight changes and changes of volume-related circumferences. This parallel shows the effectiveness of the diet applied and participants' compliance. Although the association of some circumferences with disease risk is quite well investigated [15,16,17,20,21], an eventual correlation between the above mentioned quotients and disease risk is yet to be studied.

The present work is a pilot study on FWD. The participants were healthy individuals with normal renal function, the sample size was rather small, the clinical and laboratory parameters were monitored daily, and the physician was experienced. Under these conditions, the method proved to be safe. A deeper insight in the physiology of FWD can be obtained by analyzing the hormonal, hematological, and biochemical profile including oxidative stress parameters. However, the practice of FWD requires further systematic investigation in order to determine limitations and advantages of this method.