1. Introduction
obesity, obese, nutritional deficiencies, overweight or obesity, overweight–obese, weight loss
OBESITY, OBESE, SECONDARY, NUTRITIONAL DEFICIENCIES, DISEASES
Evidence of the effectiveness of zinc (Zn) and selenium (Se) on resting metabolic rate (RMR) and physical function parameters in people with overweight and obesity is scarce, while the effects of zinc and selenium on thyroid function and body composition are still a topic of debate and controversy. The aim of this randomized, double-blind, and placebo-controlled trial was to examine the effects of a hypocaloric diet and Se–Zn co-supplementation on RMR, thyroid function, body composition, physical fitness, and functional capacity in overweight or obese individuals. Twenty-eight overweight–obese participants (mean BMI: 29.4 ± 4.7) were randomly allocated (1:1) to the supplementation group (According to the World Health Organization, the number of obese people has almost tripled since 1975 [The causes of obesity are complex and can be classified as primary and secondary, with an interaction between biological, behavioral, and psychosocial factors taking place [Growing evidence confirms that obesity increases the risk for nutritional deficiencies due to poor diet quality and a disruption of the bioavailability and metabolism of numerous nutrients despite the high caloric intake that characterizes the specific population [A systematic review of the literature indicated that people with obesity have lower levels of some antioxidants, including zinc (Zn) and selenium (Se) [Numerous systematic reviews and meta-analyses have highlighted that Se and Zn supplementation may positively affect many aspects of health in people with or without diseases and pathological conditions [Even though a diet plan can induce weight loss by creating a negative energy balance, maintaining weight loss can sometimes be challenging in the long term [Two studies examining the effects of Zn on human RMR or Basal Metabolic Rate (BMR) showed some positive results [Hawkes and Keim [In several studies, the low RMR of individuals with obesity was associated with lower cardiorespiratory fitness levels, probably due to limited physical activity levels [A recent review found that a poor Zn status in healthy individuals, as a result of a dietary consumption below the recommended daily allowances (RDA), can negatively affect their physical performance [The aim of this randomized control trial was to examine the effects of Zn and Se co-supplementation on RMR, thyroid function, exercise performance, and body composition in people with overweight or obesity undergoing a hypocaloric diet.