## 2 Materials and Methods
### Procedure  
The Ethics Committee from Catholic University San Antonio of Murcia (Murcia, Spain) reviewed and authorized the protocol designed for data collection, considering the World Medical Association Code (CE062103). All points of the Declaration of Helsinki were followed throughout the process. Participants were informed about the procedure and signed a consent form prior to starting the study. The protocol was registered at ClinicalTrials.gov (ClinicalTrials.gov Identifier: NCT04429581). First, the participants were asked to complete an ad hoc questionnaire to provide information on basic demographics (sex and age), diseases that could affect body fat (illnesses and injuries in the last six months, chronic illness and surgeries), medication taken regularly, hormonal or corticosteroid treatment (daily or occasional treatment in the last six months), last menstrual period for women, and food intake (24 h dietary recall--24 HR) and sports practice (24 h exercise recall) in the last 24 h, based on previous studies [8; 42]. They also self-completed the IPAQ questionnaire, previously validated in Spanish, with a good reliability (r = 0.82) and an acceptable validity [43]. In this study, the last 7 days self-administered long form of the IPAQ was used. The questionnaire evaluates physical activity at work, for transportation, during leisure time, and at home. The frequency (per week) and time spent on vigorous- and moderate-intensity activities and the time spent walking are registered for each category, together with the time spent sitting during a workday and on a weekend day. Explanations and practical examples for vigorous and moderate physical activities are given. To be registered, an activity must last at least 10 min, following the methodology of previous studies [43]. For data analysis, moderate intensity was defined as 4 METs (metabolic equivalent task) and vigorous intensity as more than 8 METs [44]. Walking activity was defined as 3.3 METs. One MET is the energy expended at rest and is defined as 3.5 mL O\({}_{2}\)\(\times\) kg\({}^{-1}\)\(\times\) min\({}^{-1}\). Active subjects were considered to be those who had a weekly metabolic expenditure above 600 METs [45]. Second, all the measurements were performed in a single session in a room with a standardized temperature of 24 \({}^{\circ}\)C, between 8:30 am and 1:30 pm. The anthropometric variables were taken following the protocol from the International Society for the Advancement of Kianthropometry (ISAK) [46]. Basic measurements such as body mass and height, together with triceps, subscapular, biceps, iliac crest, supraspinal, abdominal, thigh, and leg skinfolds were taken by an ISAK level 3 certified anthropometrist. To measure the body mass, the subject stood with minimal clothing in the center of the scale without support and with the weight distributed evenly on both feet. Regarding height, it was measured after having positioned its head in the Frankfort plane during a deep breath. All skinfold measurements followed the same technique. The nearer edge of the contact faces of the caliper was applied 1 cm away from the skinfold landmark done before and at the same depth that the digits that hold the fold were located. Measurements were recorded two seconds after the full pressure of the caliper was applied. A SECA 862 weighing scale (SECA, Hamburg, Germany) with an accuracy of 100 g was used for body mass, a SECA 213 portable stadiometer (SECA, Hamburg, Germany) with an accuracy of 0.1 mm was used for height measurement, and a Harpenden calliper (Harpenden, London, UK) with an accuracy of 0.2 mm was used for skinfolds. Each measurement was taken twice. Ifthe difference between them was greater than 1% for the basic measurements or greater than 5% for the skinkolds, a third measurement was taken. The final value considered for data analysis was the mean if two measurements were taken or the median if three measurements were taken. The intra-evaluator technical error of measurement (TEM) was 0.01% for basic measurements and 1.12% for skinkolds.