Study: Being overweight is not necessarily associated with premature death

DUBAI, United Arab Emirates, (CNN) — A new study has found that obesity, as measured by BMI, is not associated with obesity when viewed separately from other health problems.

BMI for adults is calculated by dividing weight by the square root of a person’s height, and people have different amounts of body fat.

According to the US Centers for Disease Control and Control (CDC), an adult is considered overweight if his BMI is between 25 and 29.9, and if the index is between 18.5 and 24.9, his weight is considered normal or healthy, and if it exceeds 30. , he is considered overweight. He suffers from obesity.

Dr. Ayush Visaria, MD, a resident physician specializing in internal medicine at Rutgers Robert Wood Johnson Medical College in New Brunswick, New Jersey, said the real news from this study is that weight gain is defined by BMI. is a poor predictor of mortality risk, and weight gain is a predictor of mortality risk. Body mass index is generally a poor predictor of health risks and should be supplemented with information provided by waist circumference, other measures of fatness, and other measurements. weight path.

According to experts not involved in the study, research limitations make it difficult to determine whether the results are due to BMI or other factors.

Dr. is a lecturer in clinical statistics at University College London. Baptiste Laurent explained, “The use of the term ‘overweight’ is misleading here because it excludes anyone with a BMI over 30. He said in a statement that the term ‘overweight’ includes anyone who weighs more than the “normal” index, including those who are obese. Generally explained.

“This paper finds a clear association between BMI and mortality before and after adjusting for risk factors,” added Laurent, who was not involved in the study.

Dr. Robert H., senior faculty editor at Harvard Health Publishing, affiliated with Harvard Medical School in Boston. Schmerling said observational studies only show correlation, not causation.

“They looked at mortality rates, but they didn’t look at other important outcomes, such as quality of life or the development of new comorbidities like new diabetes or heart disease,” Schmerling, who was not involved, said. study, said.

Death vs. Disease

In a new study published Wednesday in the journal PLOS ONE, researchers analyzed data on more than 554,000 non-pregnant Americans over the age of 20 collected from the 1999-2018 National Health Interview Survey and the 2019 US National Death Index.

Visaria, professor of medicine and epidemiology at Rutgers Robert Wood Johnson School of Medicine and Rutgers School of Public Health, and co-author Dr. Soko Setoguchi compared BMI levels with recorded deaths over the next 20 years.

Visaria noted that mortality risk increased from 18 to 108% for those with a BMI greater than 27.5, and that risk increased with overweight following a U-shaped curve.

There was one exception: adults over 65. There was no significant increase in mortality among older adults with a BMI between 22.5 and 34.9, a range that includes normal weight, overweight, and obese people.

“This paper adds nothing new,” says Naveed Sattar, a professor of cardiovascular health and metabolism at the University of Glasgow in Scotland, who was not involved in the study.

“We know that BMI often yields a U-shaped curve with mortality, but many people at the lower end of the BMI range (especially older people) experience unintentional weight loss,” Starr said in a statement. due to illness”.

Weight loss is often associated with the development of dementia and cancer, and loss of appetite in elderly patients. Previous research has found that losing at least 5% of body mass increases the risk of premature death among people 65 and older, especially men.

The study’s most important finding was that adults aged 20 to 65 with a body mass index of 24.5 to 27.5, the lowest end of the overweight scale, had no significant increase in mortality risk.

However, Tom Saunders, emeritus professor of nutrition and dietetics at King’s College London, who was not involved in the study, said future risk of disease is “the most important measure of health for all causes”.

“The main risk of being overweight (BMI 25-29.9) and moderately obese (BMI 30-35) is a threefold higher risk of developing diabetes, which contributes to cardiovascular disease, kidney failure and blindness,” he said in a statement. .

Visaria told CNN that while the study controlled for various diseases linked to smoking and premature death, the information was collected only once for each person who participated in the survey. Therefore, the study was unable to follow him later to see if he developed conditions that may have contributed to death, such as high blood pressure or diabetes, which is one of the study’s limitations.

“They don’t look at the cause of death, maybe it was a car accident or something unhealthy,” says Schmerling, former medical chief of rheumatology at Beth Israel Deaconess Medical Center in Boston.

“Besides, if you look at the big picture results, they found an increase in mortality due to obesity, so it’s not like they’re proving the usefulness of BMI for all purposes.”

Schmerling said people in the overweight category can make lifestyle changes, such as exercising, eating a healthy diet and seeking medical help, to avoid developing diabetes, heart disease or other comorbidities.

Waist circumference is an important measurement

Visaria noted that for BMI, they also examined data measuring waist circumference or abdominal thickness. The results showed that using waist circumference “significantly modifies the association between BMI and all-cause mortality.”

“People with a larger waist circumference were at higher risk of death than those with a normal waist circumference in the same BMI groups,” he added. “In the overweight BMI range (25-29.9), the risk of death was 17 to 27% higher among those with a high waist circumference compared to those with a low waist circumference,” he added.

This type of deep fat around body parts, known as abdominal or visceral fat, has been linked to a 39% higher risk of dementia in older women, and heart disease, frailty and early death in both sexes.

According to guidelines published by the American Heart Association in April 2021, waist circumference should be measured as part of any health evaluation.

And the American Medical Association recently adopted new guidelines calling on doctors to use more than BMI when assessing an individual’s health.