Obesity in Adulthood Linked to Increased Frailty Risk in Later Life

Shreeshti Uchai, EPH

Both general and abdominal obesity from mid-life onwards is associated with an increased risk of physical frailty in older age, according to new findings.

Researchers suggest frailty is often wrongly identified as a purely wasting disorder and emphasized the importance of proper weight throughout adulthood to minimize the risk.

“In the context where the population is rapidly aging and the obesity epidemic is rising, growing evidence recognizes the subgroup of ‘fat and frail’ older individuals in contrast to viewing frailty only as a wasting disorder,” wrote corresponding author Shreeshti Uchai, EPH, Department of Nutrition, University of Oslo. “...It highlights the importance of routinely assessing and maintaining optimal BMI and WC throughout adulthood to lower the risk of frailty in older age.”

Frailty is often characterized by at least 3, and pre-frailty by 1 to 2, of the following 5 criteria: unintentional weight loss, exhaustion, weak grip strength, slow walking speed, and low physical activity levels. Frailty is associated with vulnerability to falls, disability, reduced quality of life, hospital admission and death.

Investigators note that growing evidence indicates that obese older adults may be at increased risk because obesity provokes the age-related decline in muscle strength, aerobic capacity, and physical function. However, few trials have tracked weight changes and frailty risk over a long period of time.

Using the population based Tromsø Study, investigators aimed to determine whether general (body mass index [BMI]) and abdominal (waist circumference) obesity separately and jointly might affect the risk of pre-frailty/frailty. The Tromsø Study comprised seven survey waves of 45,000 residents in Norway aged 25 to 99 who lived in the city between 1974 and 2015-2016. The current study used data from wave 4 (1994-1995) to wave 7 (2015-2016).

Their final analysis included 4.509 people aged 45 or older, with an average age at baseline of 51 years and an average monitoring period lasting 21 years. Investigators categorized a BMI <18.5 as underweight, 18.5 - 24.9 as normal, 25 –29.9 as overweight, and obesity as 30 and above.

Moreover, waist circumference was categorized as normal (≤94 cm for men; ≤80 cm for women), moderate high (95–102 cm for men; 81–88 cm for women), and high (above 102 cm for men; above 88 cm for women).

By 2015-2016, data show 28% of participants were pre-frail, 1% were frail, and 70.5% were strong. In all, nearly 51% of those who were strong and 55% of those categorized as prefrail were women, according to the data.

Participants in both the strong and pre-frail/frail groups were shown to put on wait and expand their waistlines during the monitoring period, but there were higher proportions of participants with normal BMIs and waistlines at the beginning of the monitoring period in the strong group.

Potentially influential factors, such as alcohol intake and smoking, education attainment, marital status, social support, and physical activity levels, differed significantly between the strong and pre-frail/frail groups and investigators accounted for these in the analysis.

They found those who were obese in 1994 assessed by BMI alone were approximately 2.5 times more likely to be pre-frail/frail at the end of the monitoring period, when compared to those with a normal BMI. Meanwhile, those with a moderately high or high waist circumference to start off with were 57% and twice as likely to be pre-frail/frail than those with a normal waistline, respectively.

Investigators also observed those who started off with normal BMI but moderately high waist circumference, or who were overweight but had a normal waistline, were not significantly more likely to be pre-frail/frail at the end of the monitoring period. However, individuals who were both obese and had a moderately-high waist circumference at the start of the monitoring period were more likely to be pre-frail/frail.

There were higher odds of pre-frailty/frailty additionally observed among individuals who put on weight and those whose waistlines expanded than in those whose weight and waistlines remained the same.

The study, “Body mass index, waist circumference, and pre-frailty/frailty: the Tromsø study 1994−2016,” was published in BMJ Open.