Assessment of nutritional status using anthropometric index among older adult and elderly population in India

Malnutrition poses a significant risk to the older population globally, highlighting the critical role of nutrition in healthy aging. In this study, the aim is to estimate the prevalence of malnutrition among older adults aged 45–59 years and the elderly population aged 60 years and above based on their socioeconomic and demographic characteristics. Furthermore, the study examines the risk factors within a multivariate framework. A sample of 59,073 individuals aged 45 years and above from the Longitudinal Aging Study in India (LASI), Wave 1 survey constitutes the study population. This study adopts a cross-sectional design. Bivariate cross-tabulation analysis and multivariate logistic regression analysis are employed to understand the prevalence and determinants of nutritional status. About 25% of males and 37% of females below the age of 60 years are overweight (including obese), while among those aged 60 years and above, 28% of males and 25% of females are underweight. The elderly male population carries a comparatively higher burden of underweight (28%) prevalence than the females (25%) in the same age group. Overall, the urban population is less likely to be underweight [AOR: 0.41, C.I 0.38–0.43] and more likely to be overweight [AOR: 2.41, C.I 2.32–2.52]. Older adults from low economic and social strata are more likely to be underweight. In terms of bio-physical factors, individuals aged 60 years and above with infections to endemic diseases [AOR: 1.24; p-value < 0.01] and those with edentulism [AOR: 1.29; p-value < 0.01] are more likely to be underweight. As evident from the study, nutritional status among older adults is a complicated manifestation of multiple risk factors and requires potential nutritional intervention. Initiating a routine screening program at the grassroots level can effectively identify older adults and the elderly in India, facilitating the provision of nutritional care.

Outcome variable.To measure nutritional status among older adults, this study utilized the Body Mass Index (BMI), one of the most distinctive measures recommended by the World Health Organization (WHO).BMI is defined as weight (kg) divided by height squared (m 2 ).The classification of BMI follows as: below 18.5 as "underweight", 18.5-24.9as "normal", 25-29.9 as "overweight", 30-34.9 as "obese class I", 35-39.9 as "obese class II, " and over 40 "obese class III", indicating a risk to comorbidity 54 .The study participants were divided into three groups: underweight, normal, and overweight including obese.BMIs less than 18.5 were classified as underweight, 18.5-24.9as normal, and 25 and above as overweight.LASI identifies BMI as an essential indicator to define the nutritional status of older adults.BMI is widely used as an anthropometric measure of body composition and a metric to identify nutritional status 55 .It helps identify different levels of health disease risk.On the other hand, the LASI survey data does not provide any other clinical information on nutrition.Consequently, we have exclusively used the BMI indicator to define the different forms of nutritional status among older adults in India.

Exposure variables.
In this study, we controlled various socio-demographic, economic, bio-physical and behavioral factors to determine the nutritional status among older adults in India.The factors include gender (male/female), place of residence (rural/urban), marital status (married/widow/others), living arrangement (living alone/living with spouse and/or others/living with spouse and children/living with children and others/ living with others only), educational level (no schooling/less than 5 years completed/5-9 years completed/10 or more years completed), social-class (scheduled caste/scheduled tribe/other backward class-OBC/general), household size (1-2 persons/3-4 persons/5 + persons), economic status in terms of monthly per capita expenditure (MPCE) (poorest/poorer/middle/richer/richest), food availability constraint (no constraint/low constraint/ severe constraint), infection with any endemic diseases (no/yes), any mental health issues (no/yes), chewing capacity (no/partial or complete edentulism), tobacco consumption (no/yes), alcohol consumption (no/yes) and physical activity status (no/yes).
Besides considering the social, demographic and economic factors, we also considered the health and health behaviour related factors (infection of endemic disease, mental health issues, edentulism, tobacco consumption, alcohol consumption and physical activity) and its possible influence on malnutrition among older adults and elderly in India.LASI collects the specific information on endemic disease infection (water borne, vector-borne and other infectious disease like-tuberculosis and diarrhoea) prior to 2 years of the survey.

Statistical analysis.
The variables considered in the study are described using descriptive statistics.Box plot and multiple bar diagram are used to examine the range of BMI and the prevalence of different forms of nutritional status.Furthermore, bivariate cross-tabulation is used to estimate the prevalence of underweight and overweight/obese across the sub-populations.Additionally, three different logistic regression models are employed to determine the effect of selected socio-demographic, economic, bio-physical and behavioral factors on the outcome variable.Step-wise logistic regression models are estimated.Model-1 includes demographic variables; Model-2 includes demographic and economic variables; Model-3 includes demographic, economic and health variables; Model-4 includes demographic, economic, health and health behaviour variables.Model-4 is considered the final model and the corresponding results are tabulated in the main text.The extended tables are shown in the Supplementary Material.The multicollinearity between the exposure variables were checked and we did not find any VIF value beyond 2. www.nature.com/scientificreports/Ethical approval.As the study is based on secondary data available in public domain for research; no ethical approval was required from any institutional review board (IRB).

Results
Table 1 shows the description of the study population.Of the total 31,023 older adults, 39% belong to the 45-49 years age group.Forty-five percent of the older adults are male, 64% belong to rural areas, 85% are married and almost one-fifth of them belongs to the poorest wealth quintile.On the other hand, of the total elderly, 48% are males and 52% are females.The rural-urban divide reveals that 66% of the elderly population resides in rural areas.Additionally, only 64% of the elderly are married, while 33% are widowed.Around 20% of the elderly belongs to the poorest MPCE quintile.
Nutritional status of older adults and elderly.The prevalence of nutritional status of older adults and the elderly is shown in Fig. 2. Though the prevalence of underweight is almost equal among male and female older adults, females aged 45-59 years have a higher burden of overweight (26%) and obesity (11%) compared to males of the same age.The proportion of obese males is lower (4%) than the females (11%) in the 45-59 years of age group.Similar to the pattern of older adults, elderly females demonstrate higher overweight and obesity prevalence among them than the prevalence among elderly males.On the other hand, males aged 60 years and above carry a comparatively higher burden of underweight (28%) than females (25%).
Figure 3a shows the range of BMI by sex and nutritional status.The boxes are almost uniform for males and females in nutritional status except for obese males and females, means the BMI values are comparatively more dispersed above the median value among obese females than obese males.The age-sex pattern of BMI is shown in Fig. 3b.It is observed that the BMI of female older adults and elderly is more scattered compared the males.The median BMI is observed high among the older adult females than all other sub-groups.
Prevalence of underweight and overweight (includes obese) by selected characteristics.Table 2 shows the age-sex pattern of prevalence of underweight and overweight (overweight includes obese) by background characteristics of the study population.In the rural areas, the prevalence of underweight is higher than the urban areas; male (34%) and female (31%) elderly carry almost similar burden of underweight.In contrast, the prevalence of overweight is high in the urban areas irrespective of age and sex and the prevalence of overweight is as high as 58% among female older adults.
Widowed men reflect higher prevalence of underweight (37%) than widowed women.Compared to married elderly males (overweight prevalence-19%), married older adult males (overweight prevalence-26%) reflect higher prevalence and likewise, the prevalence of overweight is comparatively higher among married older adult females than their counter part males.
The prevalence of underweight is predominantly higher among the individuals who stay alone.It is also observed that among 60 + years male (underweight prevalence-34%) and female (underweight prevalence-30%) who are living alone are underweight compared to the older adult males and females.The estimated prevalence by educational status of older adults shows that those who are not educated, the prevalence of underweight is found higher for both the sexes while the prevalence of overweight is observed higher among the highly educated males.In the case of 60 + years population with no schooling, the prevalence of underweight is 39% among males and 31% among females.In contrast, the prevalence of overweight is comparatively higher among better educated female older adults (62%) as well as among female elderly (65%).The prevalence of underweight and overweight shows a difference among different social classes of India.Elderly males and females from the scheduled tribe and scheduled caste classes carry higher burden of underweight than all other social classes.The observed prevalence of underweight among ST elderly males is found 44% and 38% among ST elderly females.On the other hand, the prevalence of overweight is higher among the individuals from the upper class.
Those living with more than five members in the household, experience highest prevalence of underweight (18%).Females from the lowest MPCE quintile demonstrate a higher prevalence of underweight among them compared to females from higher MPCE quintiles.Older adults from the richest MPCE quintile demonstrate a higher burden of overweight, with a prevalence of 39% among males and 52% among females.Similarly, elderly persons from the lowest MPCE quintile demonstrate higher prevalence of underweight problem.Similarly, individuals facing constraints in food availability in household, experience a higher burden of underweight e.g., elderly males facing severe food availability constraints demonstrate a prevalence of underweight at 44%.
Elderly as well as older adult males and females with mental health issues do not exhibit a higher burden of undernutrition compared to those without mental health issues, except for female older adults.Female older adults with mental health issues demonstrate a 54% prevalence of overweight.Both elderly and older adults with partial/complete edentulism experience a higher burden of underweight, with approximately 30% of elderly males and 26% of elderly females being underweight.It is observed that individuals who consume tobacco carry higher burden of underweight prevalence than those who do no consume tobacco.Almost two-fifth of the elderly females who consume tobacco are underweight (underweight prevalence-38%).Alcohol consumption also demonstrates a higher burden of underweight.The prevalence of underweight is as high as 42% among the female elderly who consume alcohol.Both males and females in both the age groups who are not involved in physical activity carry higher burden of overweight than those who are involved in physical activity.It is observed that almost two-fifth of the older adult females are overweight.www.nature.com/scientificreports/ to be underweight, while overweight and obesity phenomenon is more likely to occur among the females.An elderly female is 20% less likely (AOR: 0.80; p-value < 0.01) to be underweight than a male elderly.The urban elderly and older adults are both less likely to be underweight with AOR 0.41 and 0.40 respectively compared to their rural counterparts.Widowed and other non-married individuals are more likely to be underweight than those who are married across all the age groups.Elderly who lives with spouse and/or others are 25% more likely (AOR: 1.25; p-value < 0.01) to be underweight and those elderly (with no spouse) who live with children and others are 19% more likely to be underweight (AOR: 1.19, p-value < 0.05).Individuals with higher educational qualification are less likely to be underweight than individuals who have never attended school.On the contrary, the higher educated elderly as well as the older adults are more likely to be overweight compared to their lesser educated counterparts.The pattern of malnutrition prevalence across social strata has revealed that people in higher social strata are less likely to be underweight.The upper-caste individuals have the lowest odds (AOR:

Discussions
Nutritional status of the older adults and elderly remains a public health challenge in India.In this context, this study provides a detailed understanding of the nutritional status of the older adults aged 45-59 years and the population aged 60 years and above using Longitudinal Ageing Survey of India, wave1.With the advancement of medical science, there has been an increase in the share of older population attributed to rising life expectancy, changing social and family structures in India, that poses the question of older population care 56 .Issues related to malnutrition among the elderly have significantly increased scholarly attention in recent years for varying reasons [57][58][59][60] .India has shown an improvement in terms of child mortality and life expectancy and with increasing life expectancy the old-age dependency ratio has shown an increase.Although India has shown progress in terms of creating better healthcare infrastructure, facilitating improved healthcare, it is still grappling with chronic diseases, co-morbidities, and socio-economic disparities.Adequate nutrition plays an essential role in maintaining overall health.Malnutrition among older adults is a manifestation of a variety of factors, and appropriate policy interventions are needed to combat against the public health burden of malnutrition among older adults and elderly 61,62 .The problem of underweight can be observed among the rural population.On the other hand, the problem of overweight is more dominated among the urban population.This could be attributable to the differences in the socioeconomic position, education, food availability, health care accessibility, sanitation etc. 63 .A study conducted by Abud et al. found that rural population in Ethiopia are significantly more malnourished (Mini Nutritional Assessment > 17) with (AOR = 2.08; 95% CI: 1.25-3.45) 57.Another study indicated that 62 percent of Bangladesh's older adults are in danger of malnutrition 64 .This brings attention to the region-based health routine screening and nutritional program interventions, especially in the rural areas.
A crucial finding of this study is that females are more overweight than the males across all the ages.This condition has also been well observed in other studies of India, where females living in urban areas and with better economic condition demonstrate a higher prevalence of overweight and obesity 65,66 .This could be associated with increased women employment and improved socioeconomic position that results in sedentary lifestyle.Further, Table 2. Prevalence of underweight and overweight among male and female older adults and elderly by selected background characteristics, India, LASI Wave 1, 2017-18.*The difference is not statistically significant (chi-square value) for male older adults, male and female elderly.www.nature.com/scientificreports/with increasing age, the metabolism of the body decreases and therefore a minimal or even a normal diet may cause weight gain 67,68 .Another study by Sinha and colleagues in 2018 highlighted the prevalence of overweight and obesity among post-menopausal women in India 69 .This study shows that the widows and unmarried individuals are more underweight while the prevalence of overweight is more among the married individuals.This indicates the loneliness experienced by elderly individuals, which exacerbates nutritional deficiencies.Despite the fact that the exact mechanism by which marriage gives health benefits is unknown, research has demonstrated that married older adults demonstrate better health and live longer 70 .This study informs that older adults who are not living with their spouse are at more risk of being underweight than those who live with their spouse.In contrast, a handful of studies show that adults are more likely to outlive their loved ones and friends with the progression of age, making them lonelier.Furthermore, the social constructs and home confinement lead to the risk of unnoticed falls or the inability to secure food supplies 71 .
Educational attainment plays a vital role as a predictor of nutritional status among the older adults.Previous studies have shown that with better health knowledge, the chances of being underweight reduces 61,72 .This study also shows that the higher educated elderly and older adults are less likely to be underweight and are more likely to be overweight.A systematic review by Kwan and colleagues in 2018 suggested that poverty is positively associated with low levels of education, low income, and difficulty in meeting the minimal nutritional demands 73 .Among the different social classes in India, the elderly as well as the older adult males and females from the scheduled caste (SC) and scheduled tribe (ST) class carry a higher burden and likelihood of underweight 59,74 .
In the present study, older adults aged 60 years and above who belong to the richest MPCE quintile has the lowest chance of being underweight; whereas the chance of being overweight is higher among them.These findings are supported by a study that suggests the income level of the caregivers enhances nutrition among older adults, while older adults who face abuse tend to skip meals and experience a deterioration in their health 59 .Another study found that food availability and affordability prevent elderly malnutrition 60 .The ever-changing family structure has been well documented in several studies in India [75][76][77] .The trend in change of family structure from joint to nuclear homes raises concerns about older adults' food intake or nutritional health.The findings are inconsistent with existing studies conducted in Thailand and South Africa that revealed an inverse association between increased household size and food quantity due to higher food expenditure and, as a result, inferior dietary quantity/quality 78,79 .The status of living alone among older adults can pose challenges related to selfcare, cooking, and proper nutrition, which may increase the risk of being underweight.Additionally, a person's nutritional health is influenced by their financial stability and well-being.The other side of the scenario can be explained as being connected to consuming a diet that is higher in fat content, which can lead to obesity-related issues 80 .
Infection with endemic diseases substantially affects the nutritional health of older adults.Although the causal relationship between nutritional status and infection is bidirectional, infections themselves contribute to malnutrition both in children and adults 81 .Gastrointestinal infections that result in diarrhea, infections such as HIV/AIDS and tuberculosis, as well as other chronic infections that cause cachexia and anemia, along with parasitic infections in the intestines leading to anemia and nutritional deficiencies, are evidence indicating nutritional deficiencies caused by infections 81,82 .Stimulation of the immune response due to infection is very common, which causes a demand for metabolically derived anabolic energy, leading to a vicious cycle of adverse nutritional conditions and increased susceptibility to infection 83,84 .
The study shows that 60 + years males with infection to endemic diseases exhibit a significantly higher prevalence of underweight than males in the age group of 45-59 years.A similar pattern is observed among females.Whereas, the prevalence of overweight is observed to be lower among both male and females in both the age groups who had an infection with any of the endemic diseases (water borne, vector borne or other infectious diseases).The multivariable logistic estimation also shows a higher likelihood of underweight associated with the infection among both the older adult and elderly populations when adjusted for all other factors.Whereas, the likelihood of being overweight is found lower among those who had an infection.This indicates that infection with an endemic disease is a risk factor for underweight among both groups of individuals.This suggests that infection to endemic diseases generally leads to the problem of underweight than overweight.
In this study it is found that the 60 + years old women with mental health issues carry a higher prevalence of underweight.When controlled for all other covariates, we do not observe any statistically significant association between mental health issues and the problem of underweight.However, older adults aged 45-59 years are more  [85][86][87] .A set of studies found that depression leads to changes in eating behaviour among older individuals and the treatment of depression causes weight loss [88][89][90] .Another study describes that depression is potentially associated with low appetite and low food-intake with increasing risk of malnutrition among the elderly 91 .
In general, the prevalence of underweight is observed to be higher among those who are partially or completely edentate, except for females aged 45-59 years.In comparison to older adults, elderly individuals carry higher prevalence of underweight.In contrast, the prevalence of overweight is generally lower among the partially or completely edentate except for women in the 45-59 years age group.The specific estimates of adjusted odds ratio of edentulism show a consistent and statistically significant association with underweight.This study shows that edentulism among older persons is a risk factor of underweight.Edentulism is associated with the food-groups consumed and hard-to-chew foods are commonly avoided among the elderly 92 .Elderly individuals who wear dentures and have compromised masticating capacity often experience more chewing pain compared to those with natural teeth.This discomfort affects their food group choices, leading to a higher risk of malnutrition among edentulous older persons [92][93][94] .Though there are confounding factors that affects the nutritional status among the older population, but tooth loss leads to reduction in intake of fruits and vegetables causing nutritional disturbance among them 95,96 .
The study also indicates that the prevalence of underweight is consistently high among the older adults as well as among the elderly population who consume tobacco.Notably, the prevalence of underweight is quite high among elderly persons who smoke compared to older adult smokers of both sexes.It is evident that consumption of tobacco is more of a risk factor which causes underweight among older adults as well as among the elderly.According to a previous study, cigarette smoking is a risk factor for undernutrition, and individuals who smoke have a higher likelihood of experiencing malnourishment 97 .A study also found that smoking negatively affects the eating habit among elderly reducing taste and smell, and anorectic effects of nicotine lower the appetite leading to a loss in body weight 98 .Like tobacco consumption, consumption of alcohol is also associated with malnutrition among elderly and it is a life-style risk factor of malnutrition 97 .Prevalence of malnutrition is higher among the alcohol consumers as alcohol consumption leads to impaired liver function affecting the protein metabolism in the body 99 .Alcohol consumption is also associated with mineral and vitamin deficiency which directly affects the nutritional status among the elderly 100 .
According to a previous study physical activity and nutrient intake both play important roles in maintaining good health throughout life, and neither of these two factors alone can help achieve optimal health unless they are combined 101 .Low cardiovascular fitness and the presence of chronic health conditions are often linked to physical inactivity, which is also a significant factor contributing to adult mortality 102 .Although nutritional status among the elderly is the manifestation of multiple factors and a complex interplay of different factors, but physical activity is associated with sarcopenia 103,104 .

Limitations
The study has several limitations.Firstly, the cross-sectional design only captures a snapshot of data at a specific point in time, and thus failing to explore the causal relationships or bring understanding of the temporal nature of the variables under investigation.Additionally, the reliance on self-reported data in cross-sectional surveys like LASI may introduce recall bias, as participants may not accurately recall or report certain information.Furthermore, cross-sectional studies are unable to account for changes or variations that may occur over time, such as seasonal effects or fluctuations in participants' nutritional health status.Another limitation is the selection bias, as certain groups of individuals may be more likely to participate in the survey, leading to a non-representative sample of the population.Lastly, cross-sectional research may not capture the complexity of longitudinal trends or developmental processes, limiting the ability to understand long-term patterns and changes.Moreover, the population survey data does not capture the nuanced and multifactorial nature of malnutrition, which requires a more comprehensive assessment involving medical examinations, nutritional assessments, and laboratory tests.Therefore, while the LASI survey data can offer valuable insights, it is important to interpret the findings cautiously and consider these limitations in the context of studying malnutrition among older adults in India.

Conclusion
Underweight and overweight are significant problems among older adults and the elderly in India.This study, the first of its kind to explain the problem of malnutrition using a nationally representative sample of the 45 years and older population and brings forth the evidence that malnutrition among the older population in India is quite substantial at the national level and across different population groups.Widowed individuals, those experiencing food insecurity, those who suffered from endemic disease, edentulism and poor health behaviour in terms of tobacco and alcohol consumption require attention to address the underweight problem among older adults.Female older adults aged 45-59 years are at a higher risk of being overweight.Urban population, individuals with mental disorders and sedentary life-style are at the risk of being overweight.Females across ages carry a higher burden of being overweight, and males in India experience a higher prevalence of underweight, especially above the age of 60 years.
It is critical to meet older individuals' nutritional demands to ensure their overall health, and quality of life.As poverty, food availability, community where they live, chronic and mental disease and their way of living are important factors which determine the nutritional condition.Thus, more multidisciplinary research needs to be conducted to gather community-based nutrition knowledge and initiate a routine screening of older adults in the population.It is also necessary to develop appropriate preventive strategies during early adulthood to www.nature.com/scientificreports/reduce the burden of underweight across different sub-populations, considering individualized nutritional needs and introducing physical examination of nutritional health.It is recommended to encourage the adult population to refrain from unhealthy behaviour, promote oral health and mental wellbeing among them to address nutritional problems.Improving the situation by addressing malnutrition among older adults and the elderly in India might prove challenging as their nutritional status reflects past experiences and practices.Therefore, the program in India should be robust from adulthood to effectively reduce the burden of malnutrition during the later phases of life.

Figure 1 .
Figure 1.Diagrammatic flow chart shows the analytical sample of the study.

Older adult Elderly Older adult Elderly Older adult Elderly Older adult Elderly
Economic factors.Elderly living in households with higher household size are less likely to be underweight.For example, elderly from the household with '3-4' members are 14% less likely to be underweight and similarly elderly from the household with '5 + ' household size is 25% less likely to be underweight compared to those elderly from the household size of '1-2' .Older adults as well as the elderly from the poorest MPCE quintile are more likely to be underweight than those from the richer MPCE class.The estimated odds associated with underweight for different MPCE classes demonstrate that the odds show a gradual decrease over the higher MPCE classes and individuals from the richest MPCE class carry the lowest odds of being underweight.In the overall 45 + years population, it is found that individuals from the richest MPCE quintile are more likely to be overweight (AOR 2.53; p-value < 0.01) and this pattern is similar in both the age groups.On the other hand, persons who experience severe household food insecurity in availability of food are 39% more likely to be underweight (AOR: 1.39; p-value < 0.01).
ContinuedVol:.(1234567890) Scientific Reports | (2023) 13:13015 | https://doi.org/10.1038/s41598-023-39167-6www.nature.com/scientificreports/Bio-physical factors.In general, individuals who have suffered endemic diseases are at a higher risk of being underweight and elderly aged 60 + years with endemic disease infection are 24% more likely to be underweight (AOR 1.24; p-value < 0.01).Presence of any mental illness does not show any statistically significant association with underweight.But individuals with any kind of mental illnesses are more likely to be overweight.Edentulism shows a strong relation with both underweight and overweight, i.e. individuals aged 60 and above with edentulism (partial or complete) are 29% (AOR 1.29; p-value < 0.01) more likely to be underweight; while, older adults with edentulism are 22% (AOR: 1.22; p-value < 0.01) more likely to be underweight.Individuals who consume tobacco carry substantially high odds to be underweight.The elderly individuals who consume tobacco (smoke or smokeless or both) are 72% (AOR: 1.72, p-value < 0.01) more likely to be underweight while older adults who consume tobacco are 75% (AOR: 1.75, p-value < 0.01) more likely to be underweight.Individuals who consume alcohol are more likely to become underweight.While those who are engaged in some physical activities like engagement in daily chores to vigorous activities like running, swimming, gym, heavy lifting etc. are less likely to become underweight or overweight across all ages.

Table 3 .
Multivariate logistic estimation for underweight and overweight (overweight includes obese) in India, LASI Wave 1, 2017-2018.®:Reference Category, ***p < 0.01, **p < 0.05, *p < 0.1.likelyto be overweight when they have mental health issues.Mental health and nutritional status are both age dependent and deteriorate with increasing age.Though good nutrition and healthy eating habit play an important role in mental health, a good mental wellbeing also determines the nutritional status