Dietary Intervention and Varying Physical Activity in Seniors
Condition: Obesity
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Exercise; Higher Protein Diet; Conventional Carbohydrate Diet
Intervention type(s): Behavioral; Behavioral; Behavioral
Intervention description(s): PRO+EX and CARB+EX groups will be prescribed an exercise program with required attendance of 3 nonconsecutive days per week. Exercise sessions will be supervised and conducted by trained graduate students in the Department of Kinesiology. Based on recommended practice, a program that combines flexibility and balance activities, weight bearing endurance exercise (walking) and resistance training to preserve lean mass will be prescribed. Each session will last ~75 min with a 35 min warm-up/aerobic exercise of mild to moderate intensity, ~30 min of resistance training, and finally, a ~10 min of balance and flexibility exercises during the cool-down period. Endurance training activities will vary but will all be weight-bearing.; PRO diet recommendations will include high quality proteins with an emphasis on lean meats with protein being targeted for every meal and snack. PRO will provide dietary protein (1.6 g.kg-1.d-1; ~30% of energy intake) with a ratio of carbohydrate/protein of <1.5 and dietary lipids at ~ 30% energy intake. Energy deficit will be determined by reducing estimated daily energy needs by ~500 kcal/d. Regarding beef intake specifically, the prescribed diet will include a minimum of one serving of beef per day, which is approximately 3 to 3.5 ounces or ~100 grams. This amount of lean cooked beef provides an average of ~25-30 grams of protein per day (www.beefnutrition.org/leanbeef.aspx). Our dietary prescription to the PRO groups that they add 3 ounces (and perhaps up to 3.5 ounces pending body size) of lean beef daily will provide an additional 25-30 grams of protein. This diet will also include 5 servings/day of vegetables and 2-3 servings/day of fruit.; For the CARB group, the diet will provide dietary protein at 0.8 g.kg-1.d-1 (~ 18% of energy intake) with a ratio of carbohydrates/protein > 3.5 and dietary lipids at ~ 30% energy intake. Through nutrition education and counseling we will ensure that the CARB group meets the RDA for protein for women of 46 grams per day from a variety of plant and animal sources. Again, energy deficit will be determined by reducing estimated daily energy needs by ~500 kcal/d. Additional recommendations will include 5 servings/day of vegetables and 2-3 servings/day of fruit. Beef intake will be discouraged in the CARB group.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: protein; physical function; muscle quality; fatigue; weight loss