Utilizing Protein During Weight Loss to Impact Physical Function and Bone

The ancillary study to the UPLIFT trial (NCT03074643) will use a 3-group design in 225 obese (body mass index [BMI] 30-45 kg/m2 or 27-<30 kg/m2 with an obesity-related risk factor), older (65-85 years) men and women at risk for disability (Short Physical Performance Battery, SPPB ≤10) who will undergo a 6-month weight loss intervention followed by a 12-month follow-up phase to test the overall hypothesis that a higher protein (1.2 g/kg body weight/day) / lower carbohydrate (CHO) diet during a 6-month weight loss intervention improves bone phenotypes compared with an isocaloric lower protein (the current Recommended Dietary Allowance (RDA), 0.8 g/kg body wt/d) / higher CHO diet, and whether continuing a higher protein / lower CHO diet for 12-months following weight loss will result in better maintenance of bone. All participants will undergo a 6-month weight loss intervention involving caloric restriction and supervised exercise followed by 12 months of follow-up with randomization to one of three groups (n=75/group): 1) Lower protein / higher CHO diet for the 6-month weight loss phase only (RecProt); 2) Higher protein / lower CHO diet for the 6-month weight loss phase only (6-mo HiProt); or 3) Higher protein / lower CHO diet for the 6-month weight loss and 12-month follow-up phases (18-mo HiProt). Vertebral and femoral volumetric bone mineral density and cortical thickness (Primary Aim) and bone marrow adipose tissue (Secondary Aim 1) will be assessed with computed tomography at baseline, 6-, and 18-months. Bone strength and fracture risk (Secondary Aim 2) will be assessed by finite element modeling at baseline, 6-, and 18-months.

Subjects are recruited using inclusion and exclusion criteria of the parent trial (UPLIFT; NCT03074643).

Inclusion criteria

• 65-85 years
• BMI: 30-45 kg/m2 or BMI 27.0 - <30.0 AND at least one of the following risk factors:

• elevated waist circumference (>35 inches in women, >40 inches in men)
• diabetes,
• hypertension,
• dyslipidemia,
• or other obesity-related comorbidities: clinically manifest coronary artery disease [e.g., history of myocardial infarction, angina pectoris, coronary artery surgery, coronary artery procedures (e.g., angioplasty) if not within the past year], other atherosclerotic disease [e.g., peripheral arterial disease, abdominal aortic aneurysm, symptomatic carotid artery disease if not within the past year], sleep apnea, or osteoarthritis of the knee or hip.
• No regular resistance training and/or aerobic exercise (>20 mins/d) for past 6 months
• SPPB ≥3 to ≤10
• No contraindications for safe and optimal participation in exercise training
• Approved for participation by Medical Director (Dr. Lyles)
• Willing to provide informed consent
• Agree to all study procedures and assessments
• Willing to consume protein/CHO supplements for up to 18 months
• Able to provide own transportation to study visits and intervention sessions

Exclusion criteria

• Weight loss (≥5%) in past 6 months
• Dependent on cane or walker
• Cognitive impairment (Montreal Cognitive Assessment, MoCA score <22)
• Severe arthritis, or other musculoskeletal disorder
• Joint replacement or other orthopedic surgery in past year
• Uncontrolled resting hypertension (>160/90 mmHg);
• Uncontrolled diabetes (hemoglobin A1c, HbA1c ≥8.0%)
• Current or recent past (within 1 year) severe symptomatic heart disease, uncontrolled angina, stroke, chronic respiratory disease requiring oxygen; uncontrolled endocrine/metabolic disease; neurological or hematological disease; cancer requiring treatment in past year, except non-melanoma skin cancers; liver or renal disease; or clinically evident edema
• Unstable Severe Depression
• Serious conduction disorder, uncontrolled arrhythmia, or new Q waves or ST-segment depressions (>3 mm at rest or ≥2 mm with exercise)
• Abnormal kidney function (estimated glomerular rate <30 based on serum creatinine, age, gender, and race)
• Anemia (Hb<13 g/dL in men; <12 g/dL in women)
• Drug abuse or excessive alcohol use (>7 drinks/week women; >14 drinks/week men)
• Use of any tobacco or nicotine products in the past year
• Osteoporosis (T-score < -2.5 on hip or spine scan)
• Regular use of growth/steroid hormones, sex steroids or corticosteroids
• Osteoporosis medication
• Protein supplements (and unwilling to stop using for duration of study)
• Weight loss medications or procedures
• Current participation in another intervention study