Effects of bathing on appetite, deep body temperature and appetite regulating hormones (A Pilot Study)

Abstract

[Background]

To prevent frailty and sarcopenia in an ageing society, exercise and nutrition are very important. On the one hand appetite loss is a problem in care requiring and demented people, on the other hyperphagia which is an obesogenic factor is also an issue that should be addressed. In Japan, there is a traditional custom to take a bath and its possibility to suppress the appetite. Although the mechanism of appetite control is explained partially due to change of gastrointestinal motility and its blood distribution, but it is not fully understood. We focused on appetite regulating hormones especially ghrelin which is thought to stimulate eating behavior and evaluated the effect of bathing on hormones at several temperatures.

[Methods]

Two healthy male subjects (18.5<BMI<25) were participated voluntarily in four trials (bathing in three different temperatures: 42℃, 33℃ and 40℃ for 15 minutes. control: no bathing). Trials began 0730 in the morning after an overnight fast. Before the start of each trial, subjects rested in a semi-supine position for 30 minutes. Subjects were bathing 15 minutes each conditions. After this, they rested for 45 minutes. Blood sample were collected at 0(before bathing), 15, 30, 60 minutes and acylated ghrelin, glucose, insulin, lactate, free fatty acid and GLP-1 were measured. Deep body temperatures were also measured at the same time. The visual analogue scale was used to assess hunger before and after the course of trials. Plasma acylated ghrelin concentrations were determined by enzyme immunoassay.

[Results]

Plasma acylated ghrelin concentrations seemed to be suppressed by bathing at 40℃ for 15 minutes and increased at 42℃ for 15 minutes.

[Conclusion]

These findings demonstrate that appetite change on bathing might be affected by plasma acylated ghrelin concentrations.