utilizing protein during weight loss to impact physical function and bone

Conditions: Obesity; Weight Loss; Diet Modification; Aging; Weight Change, Body; Dietary Habits; Osteopenia, Osteoporosis; Bone Loss; Fractures, Bone

Summary: this study is an ancillary study to the utilizing protein during weight loss to impact physical function (uplift) trial (nct03074643) to evaluate the effects of diet composition (i.e., amount of protein and carbohydrate) during a 6-month weight loss intervention and 12-months of follow-up on bone phenotypes in obese older adults. participants will receive either a protein or carbohydrate supplement along with a behavioral weight loss intervention.

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.

Eligibility criteria:
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: 1. elevated waist circumference (\>35 inches in women, \>40 inches in men) 2. diabetes, 3. hypertension, 4. dyslipidemia, 5. 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