Abstract
Resistance training and maintenance of a higher protein diet have been recommended to help older individuals maintain muscle mass. This study examined whether adherence to a higher protein diet while participating in a resistance-based exercise program promoted more favorable changes in body composition, markers of health, and/or functional capacity in older females in comparison to following a traditional higher carbohydrate diet or exercise training alone with no diet intervention. In total, 54 overweight and obese females (65.9 ± 4.7 years; 78.7 ± 11 kg, 30.5 ± 4.1 kg/m2, 43.5 ± 3.6% fat) were randomly assigned to an exercise-only group (E), an exercise plus hypo-energetic higher carbohydrate (HC) diet, or a higher protein diet (HP) diet. Participants followed their respective diet plans and performed a supervised 30-min circuit-style resistance exercise program 3 d/wk. Participants were tested at 0, 10, and 14 weeks. Data were analyzed using univariate, multivariate, and repeated measures general linear model (GLM) statistics as well as one-way analysis of variance (ANOVA) of changes from baseline with [95% confidence intervals]. Results revealed that after 14 weeks, participants in the HP group experienced significantly greater reductions in weight (E −1.3 ± 2.3, [−2.4, −0.2]; HC −3.0 ± 3.1 [−4.5, −1.5]; HP −4.8 ± 3.2, [−6.4, −3.1]%, p = 0.003), fat mass (E −2.7 ± 3.8, [−4.6, −0.9]; HC −5.9 ± 4.2 [−8.0, −3.9]; HP −10.2 ± 5.8 [−13.2, –7.2%], p < 0.001), and body fat percentage (E −2.0 ± 3.5 [−3.7, −0.3]; HC −4.3 ± 3.2 [−5.9, −2.8]; HP −6.3 ± 3.5 [−8.1, −4.5] %, p = 0.002) with no significant reductions in fat-free mass or resting energy expenditure over time or among groups. Significant differences were observed in leptin (E −1.8 ± 34 [−18, 14]; HC 43.8 ± 55 [CI 16, 71]; HP −26.5 ± 70 [−63, −9.6] ng/mL, p = 0.001) and adiponectin (E 43.1 ± 76.2 [6.3, 79.8]; HC −27.9 ± 33.4 [−44.5, −11.3]; HP 52.3 ± 79 [11.9, 92.8] µg/mL, p = 0.001). All groups experienced significant improvements in muscular strength, muscular endurance, aerobic capacity, markers of balance and functional capacity, and several markers of health. These findings indicate that a higher protein diet while participating in a resistance-based exercise program promoted more favorable changes in body composition compared to a higher carbohydrate diet in older females.
Highlights
Obesity is considered the leading cause of preventable death world-wide and is associated with a myriad of medical co-morbidities, including diabetes, arthritis, pulmonary abnormalities, urinary incontinence, cataracts, and certain types of cancer [1,2,3,4]
We have previously reported that adherence to a circuit-style resistance exercise program and adherence to a higher protein hypo-energetic diet promoted greater weight and fat loss while maintaining muscle mass and preserving resting energy expenditure in pre-menopausal and post-menopausal women under the age of 55 [29,30,31,32,33,34,35]
We have previously reported that adherence to a circuit-style resistance exercise program and a higher protein low fat diet promoted greater weight and fat loss while maintaining muscle mass and preserving resting energy expenditure to a greater degree in comparison to following a traditional higher carbohydrate low fat diet in women under the age of 55 [29,30,31,32,33,34,35]
Summary
Obesity is considered the leading cause of preventable death world-wide and is associated with a myriad of medical co-morbidities, including diabetes, arthritis, pulmonary abnormalities, urinary incontinence, cataracts, and certain types of cancer [1,2,3,4]. Obesity complicates the aging process [1,5,6,7]. The fastest growing age group in the United States are individuals over the age of 65 [13,14,15]. According to the Center for Disease Control (CDC)’s 2007–2010 National Health and Nutrition Examination Survey, 41% of individuals in the United States aged 65–74 years old and 28% of those above age 75 were obese [16]. Aging women have been shown to be less active, and more likely to suffer from falls and hip fractures, which may subsequently lead to increased health care expenditures [17,18]. Identifying strategies to promote effective weight and fat loss while maintaining muscle mass, strength, and functional capacity as women age can have significant public health implications
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