Exercise plus a thermogenic nutritional supplement to improve body composition and metabolic health in middle-aged adults with high body fat

Inclusion Criteria: Individuals will be eligible to participate in the study if they meet all of the following criteria:

1. Age: Between 50 and 65 years at the time of screening.
2. Weight status (non-obese): Body mass index (BMI) between 25.0 and 29.9 kg/m² (overweight range, without clinical obesity).
3. Metabolically challenged profile (non-obese): Presence of at least two of the following criteria, in addition to the specified BMI range:

   A) Altered body composition (primary criterion): Body fat percentage ≥ 30% in women or ≥ 25% in men, assessed by DXA.

   B) Borderline metabolic markers (one or more):
   * Fasting glucose: 100-125 mg/dL
   * Triglycerides: ≥ 150 mg/dL
   * HDL cholesterol: \< 50 mg/dL in women or \< 40 mg/dL in men
   * LDL cholesterol: ≥ 130 mg/dL

   C) Sedentary lifestyle:

   Low or very low physical activity level, defined as ≤ 600 MET·min/week according to the IPAQ questionnaire.
4. Clinical and functional status:

   * Clinically stable condition, without acute disease or recent decompensation.
   * Ability to perform moderate-intensity exercise three times per week, according to medical assessment.
5. Previous treatment and lifestyle:

   * No participation in structured exercise programs (≥ 2 days/week) during the previous 6 months.
   * No intensive hypocaloric diets or medical weight-loss treatments during the previous 3 months.
6. Administrative and ethical aspects:

   * Ability to understand study explanations and follow instructions.
   * Signed informed consent prior to initiation of any study procedures.

Exclusion Criteria: Individuals presenting any of the following conditions will be excluded from the study:

1. Clinical obesity or anthropometric extremes:

   * BMI ≥ 30.0 kg/m² (obesity).
   * Any weight-related or clinical condition that, in the judgment of the principal investigator, contraindicates participation.
2. Relevant or uncontrolled chronic diseases:

   * Previous diagnosis of type 1 or type 2 diabetes mellitus.
   * Moderate or severe cardiovascular disease (e.g., ischemic heart disease, heart failure, uncontrolled clinically significant arrhythmias).
   * Moderate or severe renal, hepatic, or respiratory disease.
   * Neurological or musculoskeletal disorders limiting or contraindicating the prescribed exercise program.
3. Pharmacological treatments interfering with energy metabolism or body weight:

   Current use (or use within the previous 3 months) of:
   * Weight-loss medications or GLP-1 receptor agonists
   * Systemic corticosteroids at moderate or high doses
   * Thyroid hormones at non-replacement doses
   * Anabolic agents or other drugs significantly affecting body composition
4. Specific prior supplementation: Use of capsaicin, phenylcapsaicin, or other thermogenic or appetite-modulating supplements within the previous 3 months.
5. Functional or cognitive limitations:

   * Cognitive, psychiatric, or mental health disorders that may impair study comprehension or protocol adherence.
   * Physical limitations preventing safe participation in exercise.
6. Substance use:

   * Alcohol consumption at levels considered high risk (\> 20 g/day).
   * Heavy smoking (\> 10 cigarettes/day), unless deemed clinically stable by the investigator.
7. Other exclusion criteria:

   * Concurrent participation in another clinical trial or interventional study.
   * Any other condition that, in the judgment of the principal investigator, may pose additional risk to the participant or significantly interfere with study outcomes.