Dietary Intervention and Varying Physical Activity in Seniors

Effects of a Higher Protein Weight Loss Diet and Exercise on Body Composition, Physical Function, and Fatigue in Overweight Older Women

The prevalence of obesity continues to increase at an alarming rate for all sectors of the population in the US. Obesity in the older adult cohort is of great concern as it is associated with reductions in mobility, declines in physical performance and increased risk for physical disability. With regard to body composition, a) fat mass has been determined to be a stronger predictor of mobility limitations than low muscle mass in older individuals and alternatively, b) leg lean mass has also been cited as a primary determinant of lower extremity physical function.

Obesity is related to increased levels of fatigue and lack of motivation and mental energy. Fatigue can be categorized as both a subjective perception and a performance decrement. Fatigue can be defined as a perceived lack of physical or mental energy while fatigability is another construct categorized by the degree of fatigue associated with activity in any dimension (i.e. physical, mental, emotional, and/or social).

The impact of a higher protein diet on muscle quality, muscle fatigability, perceptions of fatigue and systemic inflammation in older adults has not been well documented. The utility of a higher protein weight loss diet combined with resistance exercise training to augment fat mass loss, attenuate lean mass loss and improve muscle quality and physical function could potentially be of high value to overweight older women. The potential further benefits of this regimen to enhance mental energy and other aspects of psycho-social well-being are unknown.

The aims of the present study include assessing the effects of the proposed diet and exercise intervention on 1) body composition, 2) strength and muscle quality, and 3) energy and fatigue symptoms.

Our target population includes 75 overweight or obese (BMI >/= 25kg/m^2) women between the ages of 65 and 80.

This study will use a parallel-arm design. After blocking on age and BMI, 75 overweight or obese (BMI ≥ 25 kg/m2) older females (65 - 80 y old) will be randomized into three groups; PRO or CARB diet combined with exercise (PRO+EX;n=25, CARB+EX; n=25) or PRO (n=25) without exercise for 6 months. All groups will have the goal of losing ~10% of initial body weight. We anticipate an adherence rate of 80% (n = 20 in each group remaining). At the initiation of the study, all subjects will be weight stable (within 2 kg) for past 6 mos and sedentary (defined as < 1h/wk or less than 2 exercise sessions per week in the last 6 months). Eligible participants will be planning to live in the community for the duration of the study. Exclusion criteria will include any chronic disease/condition that would not permit exercise or dietary restriction or alter interpretation of data. All subjects will require personal physician clearance prior to enrollment. Main outcome variables of interest are whole body composition, regional body composition, muscle strength endurance and quality, physical function, fatigue and biomarkers related to fatigue.

Inclusion Criteria:

1. Female
2. Overweight or obese (BMI ≥ 25 kg/m2)
3. 65-80 years of age
4. English speaking
5. Plan to live in the community for the duration of the study (~6 months)
6. Weight stable (within 2 kg) for the past 6 months
7. Sedentary (defined as <1 hr/week of physical activity or less than 2 exercise sessions per week in the last 6 months)
8. Free of a history or diagnosis of renal insufficiency or disease
9. Willing to obtain physician clearance
10. Willing to be randomized to treatment groups
11. Free of any chronic disease/condition that would not permit exercise or dietary restriction or alter interpretation of data.
12. Willing to meet all study requirements and randomization
13. Non-smoking and tobacco using
14. Able to obtain transportation to the UGA campus

Exclusion Criteria:

1. Normal weight (BMI < 25 kg/m2)
2. Males
3. Dietary restrictions that do not allow for the consumption of beef, as required by our dietary protocol.
4. Weight loss surgery and/or weight loss medications usage.
5. Any metal within the body and claustrophobia which precludes MRI assessment.
6. Mini-mental state exam score < 25
7. Recent or history of unstable CVD
8. Cancer treatment within the last 5 years or active cancer
9. History of lung disease or COPD or severe asthma
10. Use of anti-inflammatory or steroid medications
11. History or severe arthritis or other medical condition that precludes ability to exercise to level needed by study
12. Current diagnosis or history of balance disorders
13. History of mental disorders, dementia, clinical depression or other disorders that preclude adherence to protocols
14. Current weight of 350 pounds of greater, due to weight restrictions on equipment