Malnutrition or healthy senescence

Fat-free mass and fat mass reference values by dual-energy X-ray absorptiometry (DEXA) in a 20-80 year-old Italian population

BACKGROUND & AIMS

To establish reference values for fat-free mass (FFM), the FFM index (FFMI), fat mass (FM) and the FM index (FMI) in an Italian adult population, developing percentile distribution curves for age brackets between 20 and 80 years.

METHODS

A multicenter, retrospective study was conducted on a sample of 1866 healthy Italian adults, 1435 females and 431 males. FFM and FM were measured by dual-energy X-ray absorptiometry. FFMI and FMI were calculated as the ratio of FFM and FM to height squared.

RESULTS

The reference range for the FFMI (25-75th percentile) was similar in all age groups, i.e. 18.7-21 kg/m(2) in men and 14.9-17.2 kg/m(2) in women. In both genders, FM, the FMI and FM as a percentage of body weight (FM%) increased with age. The reference values for FM% in the two age brackets 20-29 and 60-69 were, respectively, 13-20% and 22.5-29.3% for men and 26.1-34.9%, 32.5-39.6% for women.

CONCLUSIONS

These body composition ranges can be used by clinicians and nutritionists as reference values for a Caucasian population in the Mediterranean area when evaluating body composition variations occurring in aging, malnutrition and chronic diseases.

Influences of calorie restriction and age on energy expenditure in the rhesus monkey

Caloric restriction (CR) is known to retard the aging process, and a marker of aging is decreased energy expenditure (EE). To assess longitudinal effects of CR on EE in rhesus monkeys (Macaca mulatta), data from 41 males (M) and 26 females (F) subjected to 9 or 15 yr of CR were studied. EE and body composition of monkeys 11-28 yr of age were measured using indirect calorimetry and dual X-ray absorptiometry. Total EE (24-h EE) was divided into daytime (day EE), nighttime (night EE), and daytime minus nighttime (D - N EE). M calorie-restricted monkeys showed a lower 24-h EE (means +/- SD = 568 +/- 96 kcal/day, P < 0.0001) than controls (C; 630 +/- 129 kcal/day). Calorie-restricted M had a lower night EE (difference = 36 kcal P < 0.0001) compared with C M, but after adjusting for FFM and FM, night EE was not different between calorie-restricted and C males (P = 0.72). The 24-h EE decreased with age (13 kcal decrease/yr, P < 0.0001), but there was no difference between CR and C. Adjusted for FFM and FM, D - N EE decreased with age (9 kcal/yr, P < 0.0001), with no interaction with age (P = 0.72). The F were compared with age-matched M selected from the male cohort. F had a lower 24-h EE (496 +/- 84 kcal/day) than M (636 +/- 139 kcal/day) (P < 0.0001). Adjusting for FFM and FM, night EE was lower in F compared with M (difference = 18 kcal, P = 0.077). Night EE did not differ between calorie-restricted and C younger monkeys after adjusting for FFM and FM. In conclusion, CR did not alter the age-related decrease in EE with CR.

Fat mass rather than muscle strength is the major determinant of physical function and disability in postmenopausal women younger than 75 years of age

OBJECTIVE

Few studies have investigated the relationships between body composition, functional ability, and age-related disability in postmenopausal women. We investigated the relative role of fat mass, lean mass, and muscle strength in the development of disability in a group of healthy postmenopausal women younger than 75 years.

DESIGN

We performed a cross-sectional study among 396 independently living women aged 56-73 years, randomly selected between 8 and 30 years after menopause. Lean mass and fat mass were assessed by dual-energy x-ray absorptiometry. Muscle strength (grip and leg extensors) was assessed using dynamometry. Functional ability was estimated by Physical Performance Score, physical activity during the preceding year, and impairment in activities of daily living.

RESULTS

Of the participants, 43.7 % were overweight (25 > or = BMI < 30 kg/m2), and 17.7% were obese (BM I > or = 30 kg/m2). Higher muscle strength was observed with increasing lean body mass, and participants with higher muscle strength scored better in the physical performance score and activities of daily living. Higher fat mass was significantly associated with a lower physical performance score, lower physical activity, and a higher frequency of disability. Increasing fat mass was associated with increasing lean mass and decreasing lean/fat ratio. The increase in lean mass and muscle strength associated with higher fat mass was mainly localized in the legs.

CONCLUSIONS

Our results support the role of fat mass as the primary risk marker for disability, which might later accelerate by the age-related decrease in lean mass and the development of sarcopenia after the age of 75 years.

Basal metabolic rate in the Yakut (Sakha) of Siberia

Human indigenous circumpolar populations have elevated basal metabolic rates (BMRs) relative to predicted values; this metabolic elevation has been postulated to be a physiological adaptation to chronic and severe cold stress. The present study examines BMR in the Yakut, an indigenous high-latitude population from the Sakha Republic of Russia to determine (1) whether the Yakut show evidence of an elevated BMR, (2) if the Yakut display evidence of age-related changes in BMR, and (3) whether lifestyle differences influence BMR. BMR was measured during the late summer in 75 women and 50 men (ages 18-56 years) from the Siberian village of Berdygestiakh. Measured BMR (+/- SEM) of the entire sample was significantly elevated (+6.5%) compared to predictions based on body mass (6,623.7 +/- 94.9 vs. 6,218.2 +/- 84.7 kJ/day; P < 0.001). Additionally, measured BMR for the entire sample was significantly higher than predictions based on fat-free mass (+20.8%) and surface area (+8.9%). Males and females both showed significant elevations relative to all three standards. The elevated BMR of the Yakut does not appear to be attributable to extreme levels of protein, since the Yakut consume a mixed diet with a substantial proportion of carbohydrates. No significant age-related changes in BMR were found when controlled for body composition. No significant relationship was found between lifestyle variables and BMR, suggesting the possibility of a genetic or developmental mechanism. This study provides additional evidence of metabolic elevation in indigenous circumpolar groups and has important implications for estimating the nutritional requirements of these populations.

Body composition estimates from NHANES III bioelectrical impedance data

BACKGROUND

Body composition estimates for the US population are important in order to analyze trends in obesity, sarcopenia and other weight-related health conditions. National body composition estimates have not previously been available.

OBJECTIVE

To use transformed bioelectrical impedance analysis (BIA) data in sex-specific, multicomponent model-derived prediction formulae, to estimate total body water (TBW), fat-free mass (FFM), total body fat (TBF), and percentage body fat (%BF) using a nationally representative sample of the US population.

DESIGN

Anthropometric and BIA data were from the third National Health and Nutrition Examination Survey (NHANES III; 1988-1994). Sex-specific BIA prediction equations developed for this study were applied to the NHANES data, and mean values for TBW, FFM, TBF and %BF were estimated for selected age, sex and racial-ethnic groups.

RESULTS

Among the non-Hispanic white, non-Hispanic black, and Mexican-American participants aged 12-80 y examined in NHANES III, 15 912 had data available for weight, stature and BIA resistance measures. Males had higher mean TBW and FFM than did females, regardless of age or racial-ethnic status. Mean TBW and FFM increased from the adolescent years to mid-adulthood and declined in older adult age groups. Females had higher mean TBF and %BF estimates than males at each age group. Mean TBF also increased with older age groups to approximately 60 y of age after which it decreased.

CONCLUSIONS

These mean body composition estimates for TBW, FFM, TBF and %BF based upon NHANES III BIA data provide a descriptive reference for non-Hispanic whites, non-Hispanic blacks and Mexican Americans in the US population.

Changes in nutritional status and postoperative outcomes in elderly CABG patients

OBJECTIVES

To systematically examine the pattern of nutritional status over time in older people undergoing elective coronary artery bypass grafting (CABG) and the extent to which nutritional status affects health outcomes postdischarge.

DESIGN

The sample consisted of 91 community-dwelling English-speaking persons > or = 65 (72.27 +/- 4.85) years of age with normal cognitive function and no active cancer. Data collected prospectively at 3 time points (preoperatively, postoperatively on day 5, and 4 to 6 weeks postdischarge) included serum albumin, transferrin, and calculated Body Mass Index (BMI). The Short-Form 36 Health Status Survey Questionnaire was administered 4 to 6 weeks postdischarge as a primary health outcome measure.

RESULTS

Nutritional status changed over time. For albumin and transferrin, the pattern of change corresponded to the phases of surgical stress (P = 0.001). The BMI decreased from preoperative to 4 to 6 weeks postdischarge (P = 0.001), and this decrease explained 13.8% of the variance in physical health 4 to 6 weeks postdischarge (P = 0.008). The change in the BMI corresponds to an average weight loss of 5% from preoperative to postdischarge.

CONCLUSIONS

Older people undergoing CABG who lose significant weight from preoperative to postdischarge are more likely to have lower self-reported physical health.

Age-related differences in fat-free mass, skeletal muscle, body cell mass and fat mass between 18 and 94 years

OBJECTIVE

To determine (1) lean and fat body compartments, reflected by fat-free mass (FFM), appendicular skeletal muscle mass (ASMM), body cell mass (BCM), total body potassium (TBK), fat mass and percentage fat mass, and their differences between age groups in healthy, physically active subjects from 18 to 94 y of age; and (2) if the rate of decrease in any one of the parameters by age might be accelerated compared to others.

METHODS

A total of 433 healthy ambulatory Caucasians (253 men and 180 women) aged 18--94 y were measured by dual-energy X-ray absorptiometry (DXA) and whole body scintillation counter (TBK counter) using a large sodium iodide crystal (203 mm diameter).

RESULTS

The ASMM change (-16.4 and -12.3% in men and women, respectively) in >75 y-old compared to 18 to 34-y-old subjects was greater than the FFM change (-11.8 and -9.7% in men and women, respectively) and this suggests that skeletal muscle mass decrease in older subjects was proportionally greater than non-skeletal muscle mass. BCM (-25.1 and -23.2% in men and women, respectively) and TBK differences were greater than the differences in FFM or ASMM suggesting altered composition of FFM in older subjects. Women had lower peak FFM, ASMM, BCM and TBK than men.

CONCLUSIONS

The decline in FFM, ASMM, BCM and TBK is accelerated in men and women after 60 y of age and FFM, ASMM, BCM and TBK are significantly lower than in younger subjects. Fat mass continued to increase until around 75 y.

Fat-free and fat mass percentiles in 5225 healthy subjects aged 15 to 98 years

OBJECTIVES

Fat-free mass (FFM) and fat mass (FM) are important in the evaluation of nutritional status. Bioelectrical impedance analysis (BIA) is a simple, reproducible method used to determine FFM and FM. Because normal values for FFM and FM have not yet been established in adults aged 15 to 98 y, its use is limited in the evaluation of nutritional status. The aims of this study were to determine reference values for FFM, FM, and percentage of FM by BIA in a white population of healthy adults, observe their differences with age, and develop percentile distributions for these parameters between ages 15 and 98 y.

METHODS

Whole-body resistance and reactance of 2735 healthy white men and 2490 healthy white women, aged 15 to 98 y, was determined by 50-kHz BIA, with four skin electrodes on the right hand and foot. FFM and FM were calculated by a previously validated, single BIA formula and analyzed for age decades.

RESULTS

Mean FFM peaked in 35- to 44-y-old men and 45- to 54-y-old women and declined thereafter. Mean FFM was 8.9 kg or 14.8% lower in men older than 85 y than in men 35 to 44 y old and 6.2 kg or 14.3% lower in women older than 85 y than in women 45 to 54 y old. Mean FM and percentage of FM increased progressively in men and women between ages 15 and 98 y. The results suggested that the greater weight noted in older subjects is due to larger FM.

CONCLUSIONS

The percentile data presented serve as reference to evaluate deviations from normal values of FFM and FM in healthy adult men and women at a given age.