Michael J. Toth

Menopause‐Related Changes in Body Fat Distribution

Abstract: Menopause‐related changes in body fat distribution may partially explain the greater risk of cardiovascular and metabolic disease during the postmenopausal years. To date, however, the effect of the menopause transition on body fat distribution remains unclear. Cross‐sectional and longitudinal studies using waist circumference or the waist‐to‐hip ratio show no effect of menopause on body fat distribution. By contrast, studies using dual‐energy X‐ray absorptiometry showed increased trunk fat in postmenopausal women. Moreover, studies using computed tomography (CT) and magnetic resonance imaging (MRI) show that postmenopausal women have greater amounts of intra‐abdominal fat compared to premenopausal women. Collectively, these studies suggest that the menopause transition is associated with an accumulation of central fat and, in particular, intra‐abdominal fat. Whether menopause‐related differences in trunk or intra‐abdominal fat are independent of age and/or adiposity, however, is unclear. Thus, we recently examined the effect of menopausal status on body composition and abdominal fat distribution in 53 middle‐aged, premenopausal women (47 ± 3 years) and 28 early postmenopausal women (51 ± 4 years). Postmenopausal women had 36% more trunk fat (p < 0.01), 49% greater intra‐abdominal fat area (p < 0.01), and 22% greater subcutaneous abdominal fat area (p < 0.05) than premenopausal women. The menopause‐related difference in intra‐abdominal fat persisted (p < 0.05) after statistical adjustment for age and fat mass, whereas no differences were noted in trunk or abdominal subcutaneous fat. A similar pattern of differences in trunk, subcutaneous, and intra‐abdominal fat was observed in subsamples of pre‐ and postmenopausal women matched for age or fat mass. Our data and that of others suggest that early postmenopausal status is associated with a preferential increase in intra‐abdominal fat that is independent of age and total adiposity. Thus, CT and MRI should be used when examining menopause‐related changes in body fat distribution.

Total daily energy expenditure in free-living older African-Americans and Caucasians

Low rates of daily energy expenditure, increased energy intake, or a combination of both contribute to obesity in African-Americans. We examined whether African-Americans have lower rates of free-living daily energy expenditure than Caucasians. One hundred sixty-four (>55 yr) volunteers (37 African-American women, 52 Caucasian women, 28 African-American men, and 47 Caucasian men) were characterized for total daily energy expenditure, resting metabolic rate, and physical activity energy expenditure from the doubly labeled water method and indirect calorimetry. Absolute total daily energy expenditure was lower in women than men but was not different between African-Americans and Caucasians. However, we found race and gender differences in total daily energy expenditure after controlling for differences in fat-free mass. Total daily energy expenditure was 10% lower ( P < 0.01) in African-Americans compared with Caucasians due to a 5% lower resting metabolic rate ( P < 0.01) and 19% lower physical activity energy expenditure ( P = 0.08). Moreover, total daily energy expenditure was 16% lower ( P < 0.01) in women compared with men due to a 6% lower resting metabolic rate ( P = 0.09) and a 37% lower physical activity energy expenditure ( P = 0.06). Low rates of energy expenditure may be a predisposing factor for obesity, particularly in African-American women.Low rates of daily energy expenditure, increased energy intake, or a combination of both contribute to obesity in African-Americans. We examined whether African-Americans have lower rates of free-living daily energy expenditure than Caucasians. One hundred sixty-four (> 55 yr) volunteers (37 African-American women, 52 Caucasian women, 28 African-American men, and 47 Caucasian men) were characterized for total daily energy expenditure, resting metabolic rate, and physical activity energy expenditure from the doubly labeled water method and indirect calorimetry. Absolute total daily energy expenditure was lower in women than men but was not different between African-Americans and Caucasians. However, we found race and gender differences in total daily energy expenditure after controlling for differences in fat-free mass. Total daily energy expenditure was 10% lower (P < 0.01) in African-Americans compared with Caucasians due to a 5% lower resting metabolic rate (P < 0.01) and 19% lower physical activity energy expenditure (P = 0.08). Moreover, total daily energy expenditure was 16% lower (P < 0.01) in women compared with men due to a 6% lower resting metabolic rate (P = 0.09) and a 37% lower physical activity energy expenditure (P = 0.06). Low rates of energy expenditure may be a predisposing factor for obesity, particularly in African-American women.

Energy expenditure and symptom severity in men with heart failure

Our results demonstrate a graded increase in resting metabolic rate based on symptom severity as reflected in the New York Heart Association classification. This finding supports the hypothesis that clinical severity of illness corresponds to the magnitude of the increase in resting energy demands.

No evidence for a higher resting metabolic rate in noninstitutionalized Alzheimer's disease patients.

OBJECTIVE: It has previously been suggested that Alzheimers disease patients have higher resting energy requirements than healthy individuals, which may contribute to their unexplained weight loss. We examined whether resting metabolic rate, the largest component of daily energy expenditure, is elevated in Alzheimers patients compared with healthy older controls.

Comparing energy expenditure data among individuals differing in body size and composition: statistical and physiological considerations.

Acute and chronic diseases are frequently characterized by alterations in energy metabolism that influence nutritional requirements and clinical care. Knowledge of the effect of disease on daily energy expenditure and its components is fundamental to understanding the impact of the disease process on energy balance. To obtain this information, energy expenditure data are often compared between healthy and diseased individuals. This review focuses on the statistical and physiological issues related to comparing energy expenditure data among individuals who differ in body size and composition.

SKELETAL MUSCLE PROTEIN METABOLISM IN HUMAN HEART FAILURE

Purpose of reviewThis review considers evidence that the clinical condition of heart failure alters skeletal muscle protein synthesis and/or breakdown to promote skeletal muscle wasting and functional decrements that ultimately contribute to the symptomology of the disease. Recent findingsAdvanced HF is frequently accompanied by muscle atrophy and a cachectic phenotype. Protein metabolic derangements that promote this phenotype are understudied and poorly understood. Instead, most investigations have evaluated regulatory hormones/signaling pathways thought to be reflective of protein synthesis and breakdown. Several of these recent studies have provided exciting data suggesting that the dysfunctional myocardium releases catabolic agents that could promote the skeletal muscle myopathic phenotype either directly or through modulation of other regulatory systems (e.g., energy balance). SummaryAlthough our understanding of skeletal muscle atrophy and dysfunction in heart failure is limited, recent studies have provided clues about the nature and timing of protein metabolic dysfunction. More specifically, skeletal muscle protein metabolic derangements likely evolve during periods of disease-related stress (i.e., acute disease exacerbation and hospitalization) and potentially derive in part, from signals promoted in the damaged/dysfunctional myocardium. Despite these compelling studies, there is a surprising lack of data regarding the nature or timing of specific protein metabolic defects in heart failure.

Training status, resting metabolic rate, and cardiovascular disease risk in middle-aged men☆

We investigated differences in resting metabolic rate (RMR) and cardiovascular disease risk factors among 86 middle-aged men (36 to 59 years) classified as resistance-trained ([RT] n = 19), aerobic-trained ([AT] n = 37), or untrained ([UT], n = 30) according to habitual exercise patterns. RMR, body composition, body fat distribution, supine blood pressure, maximal aerobic capacity (VO2max), plasma lipid levels, and fasting levels of insulin, glucose, and thyroid hormones were measured. We found that RMR, adjusted for differences in fat-free mass, showed a tendency to be greater in AT men as compared with RT men (P = .09) and was greater in AT men as compared with UT men (P < .05). No differences in RMR were noted between RT and UT men. UT men had higher values for total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C), and the insulin to glucose ratio and lower values for high-density lipoprotein cholesterol (HDL-C) (all P < .01) as compared with RT and AT men, whereas no differences in these variables were noted between RT and AT men. Supine diastolic blood pressure was lower in RT men as compared with both AT and UT men. Stepwise regression analysis showed that variations in body fatness accounted for the greatest variation in fasting lipid profile, blood pressure, and the insulin to glucose ratio among groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy expenditure in wasting diseases: current concepts and measurement techniques

Weight loss occurs secondary to many acute and chronic disease states. The measurement of energy balance is crucial to understanding disease-related changes in body composition. This review considers various techniques for measuring energy expenditure in wasting diseases and the current concepts regarding the effect of disease on energy expenditure.

Prediction of resting energy needs in older men with heart failure

Objectives: Patients with congestive heart failure are often undernourished. The measurement of resting energy expenditure has served as the basis upon which estimates of daily caloric needs have been developed. Resting energy needs, however, in heart failure patients are unknown. We have developed a new equation to predict resting energy needs in heart failure patients that takes into account easily measured clinical variables and symptom severity. Design: Observational. Setting: Baltimore VA Medical Center. Subjects: Forty male patients with heart failure aged, 57–85 y; (27 Class II; 13 Class IV). Measurements: Resting metabolic rate was measured by indirect calorimetry, fat-free mass and fat mass by dual energy X-ray absorptiometry, peak VO2 by a treadmill test. Symptom severity was measured by the New York Heart Association classification. Ejection fraction, plasma albumin and plasma glucose were also assessed. Results: Stepwise regression analysis showed that body weight, fasting glucose, plasma albumin and New York Heart Association classification accounted for 83% of the variation in resting energy needs. The regression equation had a root mean square error of 130 kcal (544 kJ) per day. The equation is: RMR (kcal/d)=12.2 (wt, kg)+1.6 (glucose, gm/dl)+103 (NYHA; III, IV)−144 (albumin, mg/dl)+755. Moreover, prediction equations based on observations in healthy individuals significantly underestimated resting energy needs in heart failure patients. Conclusion: We offer a new equation to predict resting energy needs in heart failure patients based upon readily available clinical measurements. Further studies are needed to cross-validate our equation. Sponsorship: This work was supported in part by grants from the National Institute of Aging (AG-07857; KO4-AG00564) to (ETP), a predoctoral training grant from the National Institute of Aging (T32-AG00219) to (MJT), a minority supplement award to the Claude D. Pepper Older Americans Independent Center (P60-AG12583-02S1) at the University of Maryland to (TOO), and GCRC RR-109 at the University of Vermont. We would like to thank all volunteers who participated in this study. In addition, we thank Ms Gretchen Kairis, for her technical assistance and Dr SS Gottlieb, for referral of patients.

Influence of physiological factors on the age-related increase in blood pressure in healthy men

The independent and collective influences of several physiological factors on the age-related increase in blood pressure in healthy men were examined. Twenty-seven younger and 25 older, mostly normotensive, healthy men were studied. Blood pressure, body fat, body fat distribution, maximal oxygen consumption (VO2max), plasma norepinephrine, dietary Na, and erythrocyte Na-K pump activity were measured. Older men showed 57% higher percent body fat, 40% higher plasma norepinephrine concentration, 14% greater mean arterial blood pressure (MAP), and 5% higher plasma K concentration than younger men (all p < 0.01). Older men showed a 38% (p < 0.01) lower VO2max, 19% (p < 0.05) lower energy intake, 18% (p < 0.05) lower Na-K pump rate constant, and a 17% (p < 0.05) lower Na-K pump rate. Group means for MAP were adjusted for combinations of plasma norepinephrine, waist:thigh ratio, VO2max, and the Na-K pump rate constant, to determine if any one variable or combination could account for the age related increase in MAP. Statistical adjustment for plasma norepinephrine, waist:thigh ratio, and Na-K pump rate constant eliminated the significant difference between MAPs for the two groups. Thus, alterations in sympathetic nervous system activity, body fat distribution, and the membrane Na-K pump activity independently contribute to the age-related increase in MAP in healthy men.