Aging, Dietary Habits, Diet Modification, Obesity, Weight Change, Body, Weight Loss
Conditions
Brief summary
This study will 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 physical function, muscle mass, and weight loss maintenance in obese older adults. Participants will receive either a protein or carbohydrate supplement along with a behavioral weight loss intervention.
Detailed description
The study will use a 3-group design in 225 obese (BMI 27-45 kg/m2), older (65-85 years) men and women at risk for disability (eSPPB \<2.5) 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 wt/d) / lower carbohydrate (CHO) diet during a 6-month weight loss intervention improves physical function 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 improved physical function. 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). Physical function (primary aim) will be assessed by the expanded Short Physical Performance Battery (primary outcome) and lower extremity muscle strength at baseline, 6-, 12- and 18-months. Weight loss maintenance and body composition (secondary aim) will be assessed by dual-energy X-ray absorptiometry (DXA) and computed tomography (CT) at baseline, 6- and 18-months. Bone mineral density (DXA) and cardiometabolic risk factors will also be measured at baseline, 6- and 18-months.
Interventions
BEHAVIORALWeight loss intervention months 0-6
All participants will undergo a dietary weight loss intervention designed to elicit behavioral changes leading to decreased caloric intake sufficient to yield a \ 10% loss of initial body mass. The weight loss intervention will incorporate nutrition education (via group and individual meetings with the study dietitian), self-monitoring skills, cognitive-behavioral strategies for promoting lifestyle behavior modifications, and planned meals. Behavioral and educational group and individual sessions will be held weekly in a 3:1 ratio (3 group and 1 individual session per month).
BEHAVIORALExercise intervention months 0-6
All participants will be expected to participate in a supervised, center-based exercise program involving moderate-intensity aerobic exercise (e.g., treadmill walking) 3 days/wk during the 6-month weight loss intervention in accordance with the American Heart Association and the American College of Sports Medicine physical activity recommendations for older adults.
DIETARY_SUPPLEMENTCarbohydrate supplement for months 0-6
Participants in the lower protein / higher CHO diet group (RecProt) will be provided a carbohydrate supplement (\ 50 g of carbohydrate and 220 calories) to consume daily during the 6 month weight loss intervention.
DIETARY_SUPPLEMENTProtein supplement for months 0-6
Participants in the higher protein / lower CHO diet groups (6-mon HiProt and 18-mon HiProt) will be provided a protein supplement (\ 50 g of protein and 220 calories) to consume daily during the 6 month weight loss intervention.
DIETARY_SUPPLEMENTProtein supplement for follow-up months 7-18
Participants in the higher protein / lower CHO diet (18-mon HiProt) will be provided a protein supplement (\ 50 g of protein and 220 calories) to consume daily during the 12-month follow-up.
Sponsors
National Institute on Aging (NIA)
Wake Forest University Health Sciences
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Intervention model description
All participants will undergo a 6-month weight loss intervention of 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).
Eligibility
Sex/Gender
ALL
Age
65 Years to 85 Years
Healthy volunteers
No
Inclusion criteria
* 65-85 years * BMI: 27-45 kg/m2 * No regular resistance training and/or aerobic exercise (\>20 mins/d) for past 6 months * eSPPB \<2.5 * 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 (MoCA score \<22) * Severe arthritis, or other musculoskeletal disorder * Joint replacement or other orthopedic surgery in past 6 months * Uncontrolled resting hypertension (\>160/90 mmHg); * Insulin-dependent or uncontrolled diabetes (HbA1c ≥8%) * 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 (eGFR \<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, or protein supplements * Weight loss medications or procedures * Current participation in another intervention study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Expanded Short Physical Performance Battery Score | 18 months | To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in lower extremity physical function assessed by the expanded Short Physical Performance Battery score over 18 months. The expanded Short Physical Performance Battery score ranges from 0 to 4 with higher scores indicating better lower extremity physical function |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Weight Change | 18 months | To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in body weight over 18 months |
| Total Body Lean Mass | 18 months | To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in dual energy x-ray (DXA) acquired total body lean mass over 18 months |
| Lower Extremity Muscle Strength | 18 months | To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in lower extremity muscle strength assessed using an isokinetic dynamometer (Biodex) over 18 months |
| Thigh Muscle Volume | 18 months | To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in computerized tomography (CT) acquired thigh muscle volume over 18 months |
| Intermuscular Adipose Tissue | 18 months | To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in computerized tomography (CT) acquired thigh intermuscular adipose tissue over 18 months |
| Total Body Fat Mass | 18 months | To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in dual energy x-ray acquired (DXA) total body fat mass over 18 months |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| RecProt Lower protein / higher CHO diet for the 6-month weight loss phase. Exercise intervention months 0-6. Weight loss intervention months 0-6. Carbohydrate supplement for months 0-6 (blinded). Follow-up months 7-18.
Weight loss intervention months 0-6: All participants will undergo a dietary weight loss intervention designed to elicit behavioral changes leading to decreased caloric intake sufficient to yield a \
10% loss of initial body mass. The weight loss intervention will incorporate nutrition education (via group and individual meetings with the study dietitian), self-monitoring skills, cognitive-behavioral strategies for promoting lifestyle behavior modifications, and planned meals. Behavioral and educational group and individual sessions will be held weekly in a 3:1 ratio (3 group and 1 individual session per month).
Exercise intervention months 0-6: All participants will be expected to participate in a supervised, center-based exercise program involving moderate-intensity aerobic exercise (e.g., treadmill walking) 3 days/wk during the 6-month weight loss intervention in accordance with the American Heart Association and the American College of Sports Medicine physical activity recommendations for older adults.
Carbohydrate supplement for months 0-6: Participants in the lower protein / higher CHO diet group (RecProt) will be provided a carbohydrate supplement (\
50 g of carbohydrate and 220 calories) to consume daily during the 6 month weight loss intervention. | 62 |
| 6-month HiProt Higher protein / lower CHO diet for the 6-month weight loss phase. Exercise intervention months 0-6. Weight loss intervention months 0-6. Protein supplement for months 0-6 (blinded). Follow-up months 7-18.
Weight loss intervention months 0-6: All participants will undergo a dietary weight loss intervention designed to elicit behavioral changes leading to decreased caloric intake sufficient to yield a \
10% loss of initial body mass. The weight loss intervention will incorporate nutrition education (via group and individual meetings with the study dietitian), self-monitoring skills, cognitive-behavioral strategies for promoting lifestyle behavior modifications, and planned meals. Behavioral and educational group and individual sessions will be held weekly in a 3:1 ratio (3 group and 1 individual session per month).
Exercise intervention months 0-6: All participants will be expected to participate in a supervised, center-based exercise program involving moderate-intensity aerobic exercise (e.g., treadmill walking) 3 days/wk during the 6-month weight loss intervention in accordance with the American Heart Association (AHA) and the American College of Sports Medicine (ACSM) physical activity recommendations for older adults.
Protein supplement for months 0-6: Participants in the 6-month higher protein / lower CHO diet groups will be provided a protein supplement (\
50 g of protein and 220 calories) to consume daily during the 6 month weight loss intervention. | 62 |
| 18-month HiProt Higher protein / lower CHO diet for the 6-month weight loss and 12-month follow-up phases.
Exercise intervention months 0-6. Weight loss intervention months 0-6. Protein supplement for months 0-6 (blinded). Protein supplement for follow-up months 7-18.
Weight loss intervention months 0-6: All participants will undergo a dietary weight loss intervention designed to elicit behavioral changes leading to decreased caloric intake sufficient to yield a \
10% loss of initial body mass. The weight loss intervention will incorporate nutrition education (via group and individual meetings with the study dietitian), self-monitoring skills, cognitive-behavioral strategies for promoting lifestyle behavior modifications, and planned meals. Behavioral and educational group and individual sessions will be held weekly in a 3:1 ratio (3 group and 1 individual session per month).
Exercise intervention months 0-6: All participants will be expected to participate in a supervised, center-based exercise program involving moderate-intensity aerobic exercise (e.g., treadmill walking) 3 days/wk during the 6-month weight loss intervention in accordance with the AHA and the ACSM physical activity recommendations for older adults.
Protein supplement for months 0-18: Participants in the 18-month higher protein / lower CHO diet groups will be provided a protein supplement (\
50 g of protein and 220 calories) to consume daily during the 6 month weight loss intervention and 12 month follow-up. | 63 |
| Total | 187 |
Baseline characteristics
| Characteristic | RecProt | 6-month HiProt | 18-month HiProt | Total |
|---|---|---|---|---|
| Age, Continuous | 70.7 years STANDARD_DEVIATION 4.4 | 71.8 years STANDARD_DEVIATION 4.5 | 70.5 years STANDARD_DEVIATION 3.9 | 71.0 years STANDARD_DEVIATION 4.3 |
| Body mass index (BMI) | 33.8 kg per meters squared STANDARD_DEVIATION 4.6 | 34.3 kg per meters squared STANDARD_DEVIATION 3.5 | 34.3 kg per meters squared STANDARD_DEVIATION 4.2 | 34.2 kg per meters squared STANDARD_DEVIATION 4.1 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 1 Participants | 0 Participants | 0 Participants | 1 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 61 Participants | 62 Participants | 63 Participants | 186 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Black or African American | 12 Participants | 14 Participants | 19 Participants | 45 Participants |
| Race (NIH/OMB) More than one race | 2 Participants | 1 Participants | 1 Participants | 4 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) White | 48 Participants | 47 Participants | 43 Participants | 138 Participants |
| Sex: Female, Male Female | 41 Participants | 41 Participants | 42 Participants | 124 Participants |
| Sex: Female, Male Male | 21 Participants | 21 Participants | 21 Participants | 63 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 62 | 0 / 62 | 0 / 63 |
| other Total, other adverse events | 17 / 62 | 14 / 62 | 11 / 63 |
| serious Total, serious adverse events | 8 / 62 | 5 / 62 | 5 / 63 |
Outcome results
Primary
Change in Expanded Short Physical Performance Battery Score
To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in lower extremity physical function assessed by the expanded Short Physical Performance Battery score over 18 months. The expanded Short Physical Performance Battery score ranges from 0 to 4 with higher scores indicating better lower extremity physical function
Time frame: 18 months
Population: 6 participants were missing the expanded Short Physical Performance battery at 18 month follow-up: 1 participant refused the test due to severe back pain (RecProt), 3 participants refused an in-person clinic visit due to COVID-19 concerns (1 per group); 1 participant moved out of state and only completed a phone visit (6-month HiProt); and 1 participant refused to complete the expanded Short Physical Performance Battery (6-month HiProt)
| Arm | Measure | Value (LEAST_SQUARES_MEAN) | Dispersion |
|---|---|---|---|
| RecProt | Change in Expanded Short Physical Performance Battery Score | 0.06 score on a scale | Standard Error 0.08 |
| 6-month HiProt | Change in Expanded Short Physical Performance Battery Score | 0.11 score on a scale | Standard Error 0.09 |
| 18-month HiProt | Change in Expanded Short Physical Performance Battery Score | 0.16 score on a scale | Standard Error 0.09 |
p-value: 0.16ANCOVA
p-value: 0.45ANCOVA
Secondary
Intermuscular Adipose Tissue
To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in computerized tomography (CT) acquired thigh intermuscular adipose tissue over 18 months
Time frame: 18 months
Population: 19 participants were missing CT-acquired intermuscular adipose tissue: 10 participants refused the CT scan (5 RecProt, 2 6-m HiProt, 3 18-m HiProt); 4 participants had CT scans that were unable to be processed (1 RecProt, 1 6-m HiProt, 2 18-m HiProt); 3 participants refused in-person visits due to COVID-19 concerns (1 per group), 1 participant moved out of state and only did a phone visit at follow-up (6-m HiProt), and 1 person had a hip replacement of the leg scanned at baseline (18-m HiProt)
| Arm | Measure | Value (LEAST_SQUARES_MEAN) | Dispersion |
|---|---|---|---|
| RecProt | Intermuscular Adipose Tissue | 0.72 cm^3 | Standard Error 0.62 |
| 6-month HiProt | Intermuscular Adipose Tissue | 0.44 cm^3 | Standard Error 0.64 |
| 18-month HiProt | Intermuscular Adipose Tissue | 1.11 cm^3 | Standard Error 0.66 |
p-value: 0.48ANCOVA
p-value: 0.22ANCOVA
Secondary
Lower Extremity Muscle Strength
To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in lower extremity muscle strength assessed using an isokinetic dynamometer (Biodex) over 18 months
Time frame: 18 months
Population: 38 participants were missing leg strength: 34 were excluded from testing due to knee replacements, severe knee arthritis/pain, recent eye surgery or chest pain, history of brain aneurysms, or uncontrolled blood pressure (14 RecProt, 12 6-mo HiProt, 8 18-mo HiProt); 3 participants refused an in-person clinic visit due to COVID-19 concerns (1 per group); and 1 participant moved out of state and only completed a phone visit (6-mo HiProt)
| Arm | Measure | Value (LEAST_SQUARES_MEAN) | Dispersion |
|---|---|---|---|
| RecProt | Lower Extremity Muscle Strength | 8.28 Newton meters | Standard Error 4.81 |
| 6-month HiProt | Lower Extremity Muscle Strength | 6.27 Newton meters | Standard Error 5.51 |
| 18-month HiProt | Lower Extremity Muscle Strength | 7.30 Newton meters | Standard Error 5.27 |
p-value: 0.81ANCOVA
p-value: 0.8ANCOVA
Secondary
Thigh Muscle Volume
To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in computerized tomography (CT) acquired thigh muscle volume over 18 months
Time frame: 18 months
Population: 19 participants were missing CT-acquired thigh muscle volume: 10 participants refused the CT scan (5 RecProt, 2 6-m HiProt, 3 18-m HiProt); 4 participants had CT scans that were unable to be processed (1 RecProt, 1 6-m HiProt, 2 18-m HiProt); 3 participants refused in-person visits due to COVID-19 concerns (1 per group), 1 participant moved out of state and only did a phone visit at follow-up (6-m HiProt), and 1 person had a hip replacement of the leg scanned at baseline (18-m HiProt)
| Arm | Measure | Value (LEAST_SQUARES_MEAN) | Dispersion |
|---|---|---|---|
| RecProt | Thigh Muscle Volume | -3.76 cm^3 | Standard Error 2.77 |
| 6-month HiProt | Thigh Muscle Volume | -5.40 cm^3 | Standard Error 2.86 |
| 18-month HiProt | Thigh Muscle Volume | -8.42 cm^3 | Standard Error 2.96 |
p-value: 0.06ANCOVA
p-value: 0.22ANCOVA
Secondary
Total Body Fat Mass
To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in dual energy x-ray acquired (DXA) total body fat mass over 18 months
Time frame: 18 months
Population: 6 participants were missing DXA-acquired total body fat mass: 4 participants refused in-person visits due to COVID-19 concerns (1 RecProt, 1 6-m HiProt, 2 18-m HiProt), 1 participant moved out of state and only did a phone visit at follow-up (6-m HiProt), and there was a DXA machine malfunction for 1 participant (RecProt)
| Arm | Measure | Value (LEAST_SQUARES_MEAN) | Dispersion |
|---|---|---|---|
| RecProt | Total Body Fat Mass | -1.47 kilograms | Standard Error 0.92 |
| 6-month HiProt | Total Body Fat Mass | -1.68 kilograms | Standard Error 0.95 |
| 18-month HiProt | Total Body Fat Mass | -1.72 kilograms | Standard Error 0.98 |
p-value: 0.75ANCOVA
p-value: 0.95ANCOVA
Secondary
Total Body Lean Mass
To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in dual energy x-ray (DXA) acquired total body lean mass over 18 months
Time frame: 18 months
Population: 6 participants were missing DXA-acquired total body lean mass: 4 participants refused in-person visits due to COVID-19 concerns (1 RecProt, 1 6-m HiProt, 2 18-m HiProt), 1 participant moved out of state and only did a phone visit at follow-up (6-m HiProt), and there was a DXA machine malfunction for 1 participant (RecProt)
| Arm | Measure | Value (LEAST_SQUARES_MEAN) | Dispersion |
|---|---|---|---|
| RecProt | Total Body Lean Mass | -1.24 kilograms | Standard Error 0.48 |
| 6-month HiProt | Total Body Lean Mass | -1.68 kilograms | Standard Error 0.5 |
| 18-month HiProt | Total Body Lean Mass | -1.36 kilograms | Standard Error 0.52 |
p-value: 0.76ANCOVA
p-value: 0.45ANCOVA
Secondary
Weight Change
To determine the effects of a higher protein / lower CHO diet vs. lower protein / higher CHO diet during a 6-month weight loss intervention and 12 months of follow-up on change in body weight over 18 months
Time frame: 18 months
Population: Weight was not available at 18 month follow-up in 2 participants: 1 participant moved out of state and only completed a phone visit (6-month HiProt) and 1 participant refused an in-person visit at 18 months due to COVID-19 concerns (RecProt)
| Arm | Measure | Value (LEAST_SQUARES_MEAN) | Dispersion |
|---|---|---|---|
| RecProt | Weight Change | -2.67 kilograms | Standard Error 1.22 |
| 6-month HiProt | Weight Change | -3.23 kilograms | Standard Error 1.26 |
| 18-month HiProt | Weight Change | -3.28 kilograms | Standard Error 1.29 |
p-value: 0.56ANCOVA
p-value: 0.96ANCOVA