Obesity and Aging

Aging is associated with loss of beneficial effects of estrogen on leptin responsiveness in mice fed high fat diet: Role of estrogen receptor α and cytokines

Aging causes changes in body composition and energy balance. Estrogen plays an important role in body's metabolism. The aim of this study was to determine whether estrogen has beneficial effects on leptin responsiveness in aged mice. Young 4 months and aged 19-21 female mice fed High Fat Diet (HFD) or Standard Diet (SD) for 12 weeks and following received estrogen for 4 weeks. Responsiveness to leptin was compared by measuring energy balance parameters. Results showed that HFD caused weight gain compared to SD in young, but had no effect on aged animals. Estrogen reduced body weight, energy intake and visceral fat in young, while none of these parameters was affected in aged animals. Although there was leptin sensitivity in aged compared to ovariectomized animals, estrogen only improved the sensitivity of young to leptin. Estrogen prevented increase in TNF-α and a decrease in IL-10 in HFD young and aged animals. Response to estrogen depended on age, and estrogen increased leptin sensitivity only in young animals. Determining the exact mechanism of this action is suggested in future studies.

The "obesity paradox," frailty, disability, and mortality in older men: a prospective, longitudinal cohort study

An inverse relationship between overweight and mortality (the "obesity paradox") is well documented, but there are scarce data on how body weight during the life course affects this relationship. In the Helsinki Businessmen Study, we examined the effect of weight trajectories on incident disability, frailty, and mortality by stratifying 1,114 men (mean age of 47 years in 1974) into the following 4 groups based on body mass index (weight (kg)/height (m)(2)) values measured twice, in 1974 and 2000: 1) constantly normal weight (n = 340, reference group); 2) constantly overweight (n = 495); 3) weight gain (n = 136); and 4) weight loss (n = 143). Twelve-year mortality rates (from 2000 to 2012) and frailty and mobility-related disability in late life were determined. Compared with constantly normal weight, weight loss was associated with disability (odds ratio (OR) = 2.4, 95% confidence interval (CI): 1.1, 4.9) and frailty (OR = 3.7, 95% CI: 1.3, 10.5) in late life. Constant overweight was associated with increased disability (OR = 1.9, 95% CI: 1.1, 3.2). Men with constantly normal weight had the fewest comorbidities in late life (P < 0.001). Higher 12-year mortality rates were observed both with weight loss (hazard ratio = 1.8, 95% CI: 1.3, 2.3) and with constant overweight (hazard ratio = 1.3, 95% CI: 1.03, 1.7). Those with constantly normal weight or weight gain had similar outcomes. We observed no obesity paradox in late life when earlier weight trajectories were taken into account.

Dietary conjugated nonadecadienoic acid prevents adult-onset obesity in nescient basic helix-loop-helix 2 knockout mice

Conjugated linoleic acid (CLA) has been extensively studied during the last two decades with regard to its effects on controlling body composition. As a cognate to CLA, conjugated nonadecadienoic acid (CNA) has been previously reported to reduce body fat more effectively than CLA. However, it is not known whether CNA supplementation can influence adult-onset obesity. Thus, the purpose of this study was to evaluate the effects of dietary CNA on the prevention of adult-onset inactivity-induced obesity using nescient basic helix-loop-helix 2 knockout (N2KO) mice. CNA supplementation at 0.1 w/w% level starting in the preobese state significantly prevented the reduction of voluntary movement and the increase in weight gain in N2KO mice during the experimental period compared to wild-type animals. In both wild-type and N2KO mice, respiratory exchange ratio was significantly reduced by CNA treatment during light and dark cycles, and dietary CNA significantly increased energy expenditure in N2KO mice. Selected gene expression profiles in white adipose tissue, muscle or liver showed a beneficial action of CNA on lipid metabolism and energy expenditure. These findings suggest that CNA could prevent adult-onset obesity by enhancing voluntary activity and energy expenditure in N2KO mice.

Interleukin-15, IL-15 Receptor-Alpha, and Obesity: Concordance of Laboratory Animal and Human Genetic Studies

Interleukin-15 (IL-15) is a cytokine which inhibits lipid deposition in cultured adipocytes and decreases adipose tissue deposition in laboratory rodents. In human subjects, negative correlations between circulating IL-15 levels and both total and abdominal fat have been demonstrated. Deletions of IL15 in humans and mice are associated with obesity, while gain-of-function IL-15 overexpressing mice are resistant to diet-induced obesity. IL-15 is highly (but not exclusively) expressed at the mRNA level in skeletal muscle tissue, and the regulation of IL-15 translation and secretion is complex. Conflicting evidence exists concerning whether circulating IL-15 is released from skeletal muscle tissue in response to exercise or other physiological stimuli. The IL-15 receptor-alpha (IL-15Rα) subunit has a complex biochemistry, encoding both membrane-bound and soluble forms which can modulate IL-15 secretion and bioactivity. The gene encoding this receptor, IL15RA, resides on human chromosome 10p, a location linked to obesity and type-2 diabetes. Several single-nucleotide polymorphisms (SNPs) in human IL15RA and IL15 correlate with adiposity and markers of the metabolic syndrome. Genetic variation in IL15RA may modulate IL-15 bioavailability, which in turn regulates adiposity. Thus, IL-15 and the IL-15Rα may be novel targets for pharmacologic control of obesity in the human population.

Lack of the serotonin transporter in mice reduces locomotor activity and leads to gender-dependent late onset obesity

OBJECTIVE

Mice deficient of the serotonin transporter (5-HTT ko) mice have a reduced brain serotonin content and develop late-onset obesity. To elucidate the pathophysiology of this obesity, we analyzed the expression of the interrelated weight-regulatory molecules: brain-derived neurotrophic factor (BDNF) and leptin receptor (LR) in brain areas associated with nutrition and activity.

RESEARCH DESIGN AND METHODS

We investigated feeding behavior, physical activity and metabolic parameters of 5-HTT ko and wild-type mice and measured the expression of BDNF and LR in brain areas associated with nutrition and activity using quantitative real-time PCR. The influence of age, gender and fasting was analyzed.

RESULTS

Male 5-HTT ko mice developed obesity without hyperphagia from the age of 5 months. Physical activity was reduced in old male, but not old female, 5-HTT ko mice. The BDNF gene expression in frontal cortex was elevated in young, but reduced in old 5-HTT ko mice. Fasting failed to increase the BDNF gene expression in frontal cortex of young 5 HTT ko mice and in the hypothalamus in old 5-HTT ko mice. The fasting-induced hypothalamic increase of LR was absent in both young and old 5-HTT ko mice.

CONCLUSIONS

We propose that low brain serotonin level due to the 5-HTT ko genotype leads to reduced physical activity and low BDNF, which together with the lack of fasting-induced hypothalamic BDNF and LR production results in late-onset obesity. Although lack of the 5-HTT is a genetic vulnerability factor for obesity, female gender is protective.

Obesity in the Elderly

OBJECTIVE

Clinical review of the epidemiology, morbidity, mortality, medical and economic costs of being overweight or obese; recommendations on obesity from the National Institutes of Health; and how these factors relate to the elderly.

DATA SOURCES

Medline search was used to identify relevant articles. Additional references were found in review articles and consensus guidelines.

STUDY SELECTION

Fifty-nine articles were identified and 40 were selected based on findings related to geriatric patients or obesity overall. Studies done in the United States as well as in European populations were included.

DATA EXTRACTION

Data were abstracted per findings for: epidemiology of being overweight and obese for adults and elderly, mortality and morbidity of being overweight or obese, issues with weight loss in the elderly, changes in physiology with aging that may impact on weight, whether increased body mass index (BMI) is directly associated with mortality in the elderly, whether the National Institutes of Health guidelines for BMI in obesity should be applied to elderly persons, mortality associated with weight, and costs of obesity.

DATA SYNTHESIS

The main findings suggest that being underweight results in a higher mortality for elderly persons as compared with being overweight.

CONCLUSION

The primary conclusion is that it is still not yet defined if the elderly should be held to the NIH standards for "overweight" and "obesity." More research is needed to determine if overweight and obese elderly benefit from weight loss measures or if they should be kept at their current weight.

Explaining the obesity paradox: cardiovascular risk, weight change, and mortality during long-term follow-up in men

AIMS

To examine life-long weight trajectories behind the 'obesity paradox', and whether cardiovascular disease (CVD) risk contributes.

METHODS AND RESULTS

Cardiovascular disease risk and body mass index (BMI) at mean ages of 25, 47 (year 1974), and 73 years (year 2000) were available of a socioeconomically homogenous sample of 1114 men, without chronic diseases and diabetes in 1974. Overweight was defined as BMI > 25 kg/m(2), and 7-year mortality (2000-06) from the mean age of 73 years determined (188 deaths). Between 1974 and 2000, 44.3% (n = 494) were constantly overweight, 31.0% (n = 345) constantly normal weight, 12.2% (n = 136) moved from normal to overweight, and 12.5% (n = 139) moved from overweight to normal. The last group had highest CVD risk in midlife, and in late life more co-morbidities and greatest total mortality (P < 0.001). Adjusted mortality hazard ratio was 2.0 (95% confidence interval, CI 1.3-3.0; constantly normal weight group as referent). The hazard ratio remained similar (1.9, 95% CI 1.2-3.0) after adjustment for prevalent diseases in 2000.

CONCLUSION

In old age, both normal weight and overweight men are a mixture of individuals with different weight trajectories during their life course. Overweight and high-CVD risk in midlife with subsequent weight decrease predict the worst prognosis in late life.

Weight gain in overweight and obese community dwelling old-old

OBJECTIVES

The purpose of this study was to 1) investigate lifetime weight changes in community dwelling old-old, those age 80 or older; 2) explore reasons for weight changes from their personal perspective and 3) examine ways the old-old feel they can successfully lose weight. A cross sectional design was used for this qualitative study.

SETTING

One county of a southeastern U.S. state.

PARTICIPANTS

Nine community dwelling old-old.

MEASUREMENT

Content analysis of transcripts was used to examine the interviews.

RESULTS

All of the old-old interviewed had reached their maximum weight after the age of 65. Average lifetime weight gain was 73 pounds. All wanted to lose weight and found ways to incorporate small changes in their everyday lives.

CONCLUSION

With increasing life expectancy among older adults, health promotion targeting weight control needs to include the old-old.

Understanding Nutritional Health in Older Adults: A Pilot Study

A pilot study of adults ages 65 and older admitted to an acute care setting was conducted to compare nutritional risk as measured by hospital dieticians with two Nutrition Screening Initiative tools, the DETERMINE Your Nutritional Health Checklist and the Level I Screen, and to elicit from patients their own perceptions of nutritional health. Ten community-living older adults were interviewed. Although all 10 were at nutritional risk as measured by both hospital assessment and nutritional risk screening tools, none of these patients believed themselves to be at risk. One conclusion of this pilot is that interventions and education need to be tailored to the perceptions of targeted individuals.

Prevalence and correlates of overweight and obesity among older adults: findings from the Canadian National Population Health Survey

BACKGROUND

The prevalence of obesity among elderly persons in industrialized countries ranges from 15% to 20%. Little is known about variations of overweight within subgroups of the elderly population. This study examined the factors associated with overweight and obesity among older men and women.

METHODS

Data for 12,823 community-dwelling persons aged 65 and older from the 1996-1997 Canadian National Population Health Survey were examined. Predictors of overweight (body mass index [BMI] = 25.0-29.9 kg/m2) and obesity (BMI = >30 kg/m2) relative to normal weight (BMI = 20.0-24.9 kg/m2) were examined using logistic regression analyses. Analyses were stratified by gender. The predictor variables included age, education, marital status, place of birth, region, smoking status, alcohol use, chronic conditions, physical activity, functional limitations, self-rated health, social support, and psychological distress.

RESULTS

Overall, 39% and 13% of Canadian older adults were classified as overweight and obese, respectively. Some of the risk factors for overweight were male gender, low education, being married, Canadian born, residence in the Atlantic provinces, no use of alcohol, comorbidity, physical inactivity, and limited functional status. Risk factors for obesity were similar to those for overweight except for being unmarried; American, European, and Australian born; lower and higher levels of alcohol use; poor self-rated health; and psychological distress.

CONCLUSIONS

The results could lead to more effective weight-control interventions that are designed to promote increased physical activity and healthy eating habits among obese older individuals.

Hyperactivity and reduced energy cost of physical activity in serotonin 5-HT(2C) receptor mutant mice

We have observed late-onset obesity in mutant mice lacking the serotonin 5-HT(2C) receptor. Despite chronically elevated food intake, young adult mutants exhibit neither elevated adiposity nor altered glucose or fat homeostasis. However, obesity subsequently develops after 6 months of age without increases in their level of hyperphagia. In this study, we investigated determinants of energy expenditure in 5-HT(2C) receptor mutant mice. Young adult mutants displayed patterns of elevated activity levels that were enhanced by fasting and tightly associated with repeated visits to a food source. Surprisingly, subsequent obesity development occurred despite persisting locomotor hyperactivity and without age-related declines in resting metabolic rate. Rather, substantial reductions in the energy cost of locomotor activity (LA) were observed in 5-HT(2C) receptor mutant mice. Moreover, both mutant and wild-type mice displayed age-related declines in the energy cost of LA, indicating that this process may be regulated by both aging and serotonergic signaling. These results indicate that a mutation of the 5-HT(2C) receptor gene (htr2c) increases LA, which contributes to the maintenance of normal body composition in young adult mutants despite their hyperphagia. Moreover, age-dependent reductions in the energy cost of physical activity could contribute to the subsequent development of late-onset obesity in 5-HT(2C) receptor mutant mice.

Association of physical activity and visceral adipose tissue in older women and men

OBJECTIVE

Physical inactivity, abdominal fat, and age are known risk factors for diabetes, cardiovascular disease, and certain cancers. Previous evidence supports an inverse relationship between physical activity (PA) and abdominal fat estimated by waist circumference. However, few investigations used computed tomography (CAT) scanning for precise measures of abdominal fat.

RESEARCH METHODS AND PROCEDURES

Sixty-five female and 106 male (age, 64.5 +/- 5.2 years) participants in the Prostate, Lung, Colon and Ovarian Cancer Screening Trial underwent a cross-sectional L4-L5 CAT scan to differentiate visceral adipose tissue (VAT). Subjects were also interviewed by phone to determine PA and physical difficulties (PD).

RESULTS

Women had lower VAT (170 +/- 84 vs. 205 +/- 95 cm(2), p = 0.014), lower VAT/total fat (29.9 +/- 7.2% vs. 42.6 +/- 10.2%, p < 0.001), and higher total fat (596 +/- 385 vs. 482 +/- 183 cm(2), p = 0.010) than men. PA was inversely correlated to VAT (r = -0.164, p = 0.034) and total fat (r = -0.231, p = 0.003) in men and women. Those who reported a PD had higher VAT (249 vs. 180 cm(2), p < 0.001) and total fat (652 vs. 500 cm(2), p = 0.008). Multiple regression analysis indicated total PA and PD were independently associated to VAT and total fat.

DISCUSSION

This investigation suggests a beneficial effect of PA and a negative influence of PD on abdominal fat accumulation. Although the cross-sectional design limits cause-effect designations, these results are consistent with other studies showing PA/abdominal fat relation.

The 2030 problem: caring for aging baby boomers

OBJECTIVE

To assess the coming challenges of caring for large numbers of frail elderly as the Baby Boom generation ages.

STUDY SETTING

A review of economic and demographic data as well as simulations of projected socioeconomic and demographic patterns in the year 2030 form the basis of a review of the challenges related to caring for seniors that need to be faced by society.

STUDY DESIGN

A series of analyses are used to consider the challenges related to caring for elders in the year 2030: (1) measures of macroeconomic burden are developed and analyzed, (2) the literatures on trends in disability, payment approaches for long-term care, healthy aging, and cultural views of aging are analyzed and synthesized, and (3) simulations of future income and assets patterns of the Baby Boom generation are developed.

PRINCIPAL FINDINGS

The economic burden of aging in 2030 should be no greater than the economic burden associated with raising large numbers of baby boom children in the 1960s. The real challenges of caring for the elderly in 2030 will involve: (1) making sure society develops payment and insurance systems for long-term care that work better than existing ones, (2) taking advantage of advances in medicine and behavioral health to keep the elderly as healthy and active as possible, (3) changing the way society organizes community services so that care is more accessible, and (4) altering the cultural view of aging to make sure all ages are integrated into the fabric of community life.

CONCLUSIONS

To meet the long-term care needs of Baby Boomers, social and public policy changes must begin soon. Meeting the financial and social service burdens of growing numbers of elders will not be a daunting task if necessary changes are made now rather than when Baby Boomers actually need long-term care.

Aging is associated with resistance to effects of leptin on fat distribution and insulin action

Leptin has been shown to modulate total body fat and visceral fat distribution and to enhance insulin action in young rats. We hypothesize that failure of leptin action may contribute to the increase in visceral fat and insulin resistance in aging. By chronic subcutaneous infusion of leptin over 7 days, we increased leptin levels in young rats to match the levels in aging ad libitum fed rats. Leptin induced an approximately 50% decrease in food intake compared with saline controls, an approximately 50% decrease in visceral fat, and improved hepatic (fourfold) and peripheral (30%) insulin action (euglycemic hyperinsulinemic clamp technique) compared with the pair-fed group (p <.001). Although the plasma leptin level was doubled in aging rats, leptin failed to produce a significant change in food intake, in fat mass and its distribution, and in hepatic and peripheral insulin action. Increasing plasma leptin levels failed to suppress leptin gene expression in aging rats as compared with the approximately 50% suppression seen in young rats (p <.01). We propose that leptin resistance may play a causative role in the metabolic decline seen with aging.

Leptin resistance during aging is independent of fat mass

Increased fat mass, abdominal adiposity, and insulin resistance are typical findings in aging mammals and are frequently associated with leptin resistance and increased plasma leptin levels. To examine whether leptin's failure in aging is due to aging per se or to changes in body fat mass or distribution, we studied aging rats that underwent calorie restriction throughout their lives, maintaining their youthful body fat pattern and metabolic profile. Leptin's action was assessed by measuring its ability to regulate food intake, fat mass and its distribution, peripheral and hepatic insulin action, and its own gene expression in fat. Our results show that leptin's action is markedly diminished in aging rats, independently of their body fat pattern. Leptin's failure in this model suggests its causative role in the metabolic decline seen with aging.