A bulging belly might be linked to early physical decline and age-related infirmity.

Researchers in Norway recently released a prospective cohort study that looked into the relation body mass indexes (BMI) and waist circumferences (WC) have on "pre-frailty" and "frailty" in older adults, and they published their findings in BMJ Open, a peer-reviewed open access medical journal.

The study was co-authored by Shreeshti Uchai, Lene Frost Andersen, Laila Arnesdatter Hopstock and Anette Hjartåker, all of whom are faculty members at the University of Oslo’s nutrition department and the UiT The Arctic University of Norway’s community medicine department.

A total of 4,509 study participants from Tromsø, Norway, were examined over a 21-year period with 2,340 of the participants being women and 2,169 of the participants being men.

The study participants were at least 45 years old from 1994 to 1995 – the study’s starting point – and they reportedly had their body mass index and waist circumferences measured in 2001 and again from 2007 to 2008.

"Physical frailty was defined as the presence of three or more and pre-frailty as the presence of one to two of the five frailty components suggested by Fried et al: low grip strength, slow walking speed, exhaustion, unintentional weight loss and low physical activity," the study stated in its primary outcome measure.

Trained personnel reportedly measured the study participants and calculated their BMI by recording each subject’s weight and dividing it by the square of their height (kilograms by meter squared).

Waist circumference categories defined by the WHO

Normal: Less than or equal to 31.5 inches for women | Less than or equal to 37 inches for men

Moderately high: 31.9 to 34.6 inches for women | 37.4 to 40.2 inches for men

High: Greater than 34.6 inches for women | Greater than 40.2 inches for men

The study’s researchers report that they used the World Health Organization’s (WHO) established "Classification of adults according to BMI" chart to categorize which participants were "underweight" (less than 18.5 kg/meter squared), "normal" (18.5 to 24.9 kg/meter squared), "overweight" (25 to 29.9 kg/meter squared) and "obese" (greater than or equal to 30 kg/meter squared).

The study’s researchers also report that they followed the WHO’s established waist measurement categorization and sorted each study participant’s waist circumference into a "normal," "moderately high" or "high" category.

Study participants who were baseline obese or had a high to moderately high waist circumference were found to be more prone to pre-frailty and age-expected frailty compared to those who had a normal BMI and waist circumference, according to the study’s results summary.

There were "no significantly increased odds for pre-frailty/frailty" in study participants who had a normal BMI with a moderately high or high waist circumference and those who were baseline overweight with a normal waist circumference.

Based on the study’s 21-year analysis, the research paper reported that there are "increased odds of pre-frailty/frailty" for people who are obese with a moderately high or high waist circumference, people who are in the overweight to obese category and people who are on an increasing obesity trajectory.

Study participants who had a high waist circumference throughout the study’s follow-up were found to have a higher likelihood of being pre-frail or frail in old age compared to their "stable normal" waist circumference counterparts.

"Both general and abdominal obesity, especially over time during adulthood, is associated with an increased risk of pre-frailty/frailty in later years," the study concluded. "Thus maintaining normal BMI and WC throughout adult life is important."

The WHO says a "healthy diet" includes a combination of various food staples – including cereals (wheat, barley, rye, maize or rice), starchy tubers or roots (potato, yam, taro or cassava), legumes (lentils and beans), fruits, vegetables and animal sources (meat, fish, eggs and milk).

In terms of exercise, the WHO recommends at least 150 to 300 minutes of moderate aerobic physical activity or at least 75 to 150 minutes of vigorous aerobic physical activity for adults who are 18 years old and older.

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