PTH and obesity disorder: The present study confirms that people with obesity have lower blood concentrations of 25(OH)D and higher concentrations of PTH than non-obese persons, despite a higher habitual intake of vitamin D. A possible explanation is that people with obesity may usually have lower skin UV sun exposure, as it has been reported that they have reduced outdoor activity during the summer and that they generally prefer to cover as much of the body with clothes as possible [18,19].