2.4. Study Protocol
Participants arrived in the morning for their first assessment visit. The study was conducted by a team of clinicians and nutritionists. The aim of the study was explained to eligible participants by a medically qualified investigator, and if the participants agreed, they signed the informed consent. Anthropometric (weight, height) and BP measurements were taken to confirm eligibility. Total energy requirements were determined to calculate the 40% caloric-restricted diet. Subjects were then randomised into one of the two interventions (CR + BRJ or CR alone).After seven days, participants returned to the research centre to obtain information on the dietary and lifestyle intervention and to perform the baseline measurements. Participants arrived early in the morning after fasting for at least 8 h, provided urine and saliva samples, and then their REE was measured by indirect calorimetry. This was followed by measurements of endothelial function and resting BP. Next, bioelectrical impedance assessed body composition, and readings of bilateral hand-grip strength were taken. Subjects then completed a series of questionnaires, including an assessment of cognitive function, dietary intake, and physical activity level. After that, participants were provided with details about the CR interventions and, if allocated to the beetroot group, they were given 14 bottles of beetroot juice. The subjects started the intervention the day after the visit and continued for 14 days. On the 15th day, subjects arrived early in the morning fasting, and measurements were repeated in the same order as at the baseline visit. A description of the study protocol is provided in 