The goal of this randomized controlled two-arm trial is to determine the effect of a diet and exercise intervention for 12 weeks on body composition, muscle function, and energy balance in 80 adults aged 50 years and over with obesity and insulin resistance. The main questions the trial aims to answer are: Will 12 weeks of a structured nutrition plan + exercise reduce fat mass, improve muscle function, and increase energy deficit compared to the usual diet + exercise. The hypothesis is that 12 weeks of a structured nutrition plan + exercise will reduce fat mass, improve muscle function, and produce greater energy deficit than the usual diet + exercise. Participants will be provided with all meals for 12 weeks and will exercise at the Center under supervision three times each week. Pre and post-intervention, body composition, physical function, and energy deficit will be measured.

In the United States nearly one third of adults over 60 years of age have sarcopenic obesity which encompasses the combined effect of muscle impairment and obesity. A strategy that addresses the combined effect of muscle impairment and obesity while modulating muscle mass and composition is an unanswered challenge. This 12-week study will evaluate the effects of a structured nutrition plan combined with an exercise program on body fat and muscle mass, lower-extremity function (Short Physical Performance Battery), muscle strength (handgrip and knee strength), and daily caloric intake. The study will enroll adults aged 50 years and older with obesity (body mass index ≥ 30 kg/m²) and insulin resistance as indicated by a homeostasis model assessment of insulin resistance (HOMA-IR) score ≥ 3. Subjects will be randomly allocated to receive the structured nutrition plan and exercise intervention or to their usual diet and exercise in equal numbers (40 per group). The study will enrich our understanding of the physiological adaptations necessary for effective lifestyle interventions to improve muscle function.

Inclusion Criteria:

1. Age > 50 years.
2. Body mass index (BMI) ≥ 30 kg/m2.
3. Homeostatic model assessment of insulin resistance ≥ 3.
4. Mini-Mental State Examination (MMSE) > 25.
5. Geriatric Depression Scale-15 (GDS-15) < 9.
6. Sedentary (less than 90 minutes/week of moderate to vigorous activity).
7. Ability to provide written informed consent.

Exclusion Criteria:

1. Diagnosis of cancer (received within five years) or diabetes (type 1 and 2), or significant musculoskeletal, or cardiovascular, or hepatic, or renal, disease or dysfunction.
2. Clinically significant gastrointestinal malabsorption syndromes such as chronic diarrhea, celiac disease, or clinically significant abnormal laboratory markers.
3. Fluctuation in body weight > 3 kg in the preceding two months
4. Condition that impedes testing of the study hypothesis or makes it unsafe to exercise or consume the study foods.

At this time, we do not have plans to share IPD. We may consider it after the study results have been publicly disseminated