Transition to a More even Distribution of Daily Protein intake Is Associated with Enhanced Fat Loss during a Hypocaloric and Physical Activity Intervention in Obese Older Adults

BACKGROUND

Optimization of intentional weight loss in obese older adults, through preferential fat mass reduction, is challenging, as the concomitant lean mass loss may exacerbate sarcopenia. Recent studies have suggested within-day distribution of protein intake plays a role in determining body composition remodeling. Here, we assessed whether changes in within-day protein intake distribution are related to improvements in body composition in overweight/obese older adults during a hypocaloric and exercise intervention.

METHODS

Thirty-six community-dwelling, overweight-to-obese (BMI 28.0-39.9 kg/m2), sedentary older adults (aged 70.6±6.1 years) were randomized into either physical activity plus successful aging health education (PA+SA; n=15) or physical activity plus weight loss (PA+WL; n=21) programs. Body composition (by CT and DXA) and dietary intake (by three-day food records) were determined at baseline, 6-month, and 12-month follow-up visits. Within-day protein distribution was calculated as the coefficient of variation (CV) of protein ingested per defined time periods (breakfast [5:00-10:59], lunch [11:00-16:59] and dinner [17:00-1:00]). Secondary analysis was performed to determine associations between changes in protein intake distribution and body composition.

RESULTS

In both groups, baseline protein intake was skewed towards dinner (PA+SA: 49.1%; PA+WL: 54.1%). The pattern of protein intake changed towards a more even within-day distribution in PA+WL during the intervention period, but it remained unchanged in PA+SA. Transition towards a more even pattern of protein intake was independently associated with a greater decline in BMI (P<0.05) and abdominal subcutaneous fat (P<0.05) in PA+WL. However, changes in protein CV were not associated with changes in body weight in PA+SA.

CONCLUSION

Our results show that mealtime distribution of protein intake throughout the day was associated with improved weight and fat loss under hypocaloric diet combined with physical activity. This finding provides a novel insight into the potential role of within-day protein intake on weight management in obese older people.

Serum Vitamin D and Age-Related Muscle Loss in Afro-Caribbean Men: The Importance of Age and Diabetic Status

BACKGROUND

Prospective studies examining the potential association of vitamin D with age-related muscle loss have shown inconsistent results.

OBJECTIVE

To examine the association between baseline serum 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), and prospective change in lean mass with aging in African ancestry population. We also determined if associations were modulated by age and diabetes mellitus (DM).

DESIGN

Prospective observational cohort study.

SETTING

Data were collected from a random sub-sample of 574 men, participants of the Tobago Bone Health Study (TBHS).

PARTICIPANTS

574 Afro-Caribbean men, aged 43+ years (mean age: 59.1 ± 10.5), who were randomly selected as the participants in both the baseline and the follow-up visits.

MEASUREMENTS

Baseline fasting serum 25(OH)D was measured using liquid chromatography mass spectrometry (LC-MS/MS), and and 1,25(OH)2D was measured using radioimmunosassay (RIA). Changes in dual-energy X-ray absorptiometry (DXA)-measured appendicular lean mass (ALM), and total body lean mass (TBLM) were measured over an average of 6.0 ± 0.5 years. The associations of 25(OH)D and 1,25(OH)2D with ALM and TBLM were assessed by multiple linear regression model after adjusting for potential confounders.

RESULTS

When stratifying all men into two groups by age, greater baseline 25(OH)D and 1,25(OH)2D levels were associated with smaller losses of ALM and TBLM in older (age 60+ years) but not in younger (age 43 - 59 years) men. When stratifying by DM status, the associations of 25(OH)D and 1,25(OH)2D with declines in ALM and TBLM were statistically significant only in prediabetic, but not among normal glycemic or diabetic men.

CONCLUSION

Higher endogenous vitamin D concentrations are associated with less lean mass loss with aging among older and prediabetic Afro-Caribbean men independent of potential confounders. Our findings raise a possibility that maintaining high serum vitamin D level might be important for musculoskeletal health in elderly and prediabetic African ancestry men.

Effects of Changes in Regional Body Composition on Physical Function in Older Adults: A Pilot Randomized Controlled Trial

BACKGROUND/OBJECTIVE

Obesity exacerbates age-related physical disability; however, observational studies show that any weight loss in old age is associated with greater risk of mortality. Conversely, randomized controlled trials in older adults show that weight loss is beneficial. The discrepancy may be due to weight loss intention and differential changes to regional body composition. The purpose of this research was to evaluate the independent role of regional body composition remodeling in improving physical function.

DESIGN

Pilot Randomized Controlled Trial.

SETTING

Community based research center.

PARTICIPANTS

Thirty-six community dwelling, overweight to moderately obese (BMI 28.0-39.9 kg/m2) older adults (age 70.6±6.1 yrs).

INTERVENTION

Physical activity plus weight loss (PA+WL, n=21) or PA plus successful aging (SA) education. PA consisted primary of treadmill walking supplemented with lower extremity resistance and balance training. The WL program was based on the Diabetes Prevention Project and aimed at achieving a 7% weight loss by cutting calories, specifically those from fat.

MEASUREMENTS

At baseline, 6- and 12-months, body composition was measured using computerized tomography and dual x-ray absorptiometry. Abdominal visceral (VAT) and thigh intermuscular (IMAT) adipose tissue were quantified. Physical function was assessed using the short physical performance battery (SPPB).

RESULTS

Separate multivariable linear regression models with both groups combined demonstrated that decreases in IMAT and VAT were significantly associated with improvements in SPPB (P<0.05) independent of change in total fat mass. PA+WL improved SPPB scores from baseline (0.8±1.4, P<0.05), whereas PA+SA did not; however no intergroup difference was detected. Of note, these effects were mainly achieved during the intensive intervention phase.

CONCLUSION

Decreases in IMAT and VAT are important mechanisms underlying improved function following intentional weight loss plus physical activity.