The World Health Organization estimates that more than 650 million people worldwide suffer from obesity (BMI ≥30 kg/m2). According to large observational studies, obesity is associated with a 3-8 year reduction in disease/lifespan, and the risk of premature death due to obesity is approximately 13 times higher than in people of normal weight. In addition, obesity predisposes people to a wide variety of clinical conditions, including type 2 diabetes, cardiovascular disease, chronic kidney disease, site-specific cancers, musculoskeletal disorders, and infections.
Nature-Aging published a study titled "The obesity paradox is mostly driven by decreased noncardiovascular disease mortality in the oldest old in China: a 20-year prospective cohort study" published April 25. In this study, a 20-year prospective cohort study from Chinese scholars showed that overweight or mild obesity in older people over the age of 80 may be the most conducive to healthy longevity.
The research team analyzed the follow-up data of more than 27,000 elderly people aged 80 and above in mainland China from 1998 to 2018 and found that compared with the elderly with normal BMI (18.5 to 23.9), the risk of death and disability of daily life self-care ability increased by about 30%, while the corresponding risk of overweight and mild obesity (24.0 to 31.9) decreased by about 20%.
The results of the analysis showed that the risk of all-cause death and the risk of cardiovascular/non-cardiovascular disease death decreased with the increase of the BMI index in the group of 80 years and the group, and the optimal BMI index was in the range of overweight to moderate obesity. In particular, the optimal BMI for the risk of all-cause death and the risk of non-cardiovascular disease death is already close to the range of obesity.
The researchers further analyzed the association between the risk of death and waist circumference (an indicator of abdominal fat accumulation) and showed that the risk of all-cause death and the risk of death from non-cardiovascular disease decreased with the increase in waist circumference. It is worth noting that the risk of cardiovascular disease death rises in men with increased waist circumference, and in women it is associated with inverted waist circumference.
Therefore, for the elderly without basal lesions, there is no need to dwell on the weight posture, and mild obesity is not a bad thing but a good thing. However, for the elderly who suffer from high blood sugar, high blood pressure, and high blood lipids, it is still necessary to control the risk of death from weight loss and cardiovascular disease.
BMI, or body mass index, is currently a commonly used international standard to measure the degree of fat and thin body and whether it is healthy. BMI = weight (Kg) divided by height square (m2). The previously proposed BMI index greater than 25 is overweight and greater than 30 is obese.
The optimal BMI associated with the risk of all-cause death in the elderly study was 29.3, the best BMI associated with the risk of death from cardiovascular disease was 26.5, and the best BMI associated with the risk of death from non-cardiovascular disease was 30.6. These optimal BMI were all over the previously proposed 25, reaching the range of being overweight or even obese. This study suggests that the previously recommended optimal BMI may not be appropriate for older adults aged 80 years and older in China. For them, the best BMI index should probably be raised. This also suggests that we should take into account age factors in the formulation of relevant health recommendation indicators, and cannot be generalized.
Coincidentally, another study from Circulation titled "Myocardial Rev-erb-Mediated Diurnal Metabolic Rhythm and Obesity Paradox" showed that obese people with heart failure had a better prognosis than non-obese people.
Animal experiments with high-fat, high-sucrose feeds can improve heart function in mice, while high-fat sucrose-free feeds do not improve. The researchers found that high-fat high-sucrose feeds lead to significant obesity and insulin resistance, while high-fat sucrose-free feeds have little effect, and high-fat high-sucrose feeds provide fat reserves for lipolysis to produce free fatty acids while causing obesity in mice. More interestingly, fatty acid oxidation gene expression in the hearts of rev-CKO mice fed with high-fat, high-sucrose feed was only increased during the day (sleep period) compared with the regular feed group, and at night it was no different from the regular feed. In addition to fats from food during awakening, free fatty acids produced by hydrolysis of adipose tissue during sleep are important substrates for cardiac oxidative metabolism.
This phenomenon has been called the "obesity paradox" by researchers. The obesity paradox began in 1999 when Schmidt, a researcher at the University of Mississippi Medical Center, and colleagues in the United States, unexpectedly found that the survival advantage of overweight and obese kidney failure patients undergoing hemodialysis was more pronounced compared to normal weight, a phenomenon described as the "obesity-survival paradox.". Since the discovery of the "obesity paradox" phenomenon, there has been controversy about its rationality in academic circles. This study supports the obesity paradox in the elderly population (80 years and older) in China, and confirms and explains the previous "obesity paradox" research results.
In general, young people still have to maintain an appropriate weight and BMI, and exercise actively, while the elderly do not have to blindly pursue weight loss and fat removal. Whether you are fat or thin, good health is the most important!
Resources:
Song S, et al. Myocardial Rev-erb-Mediated Diurnal Metabolic Rhythm and Obesity Paradox. Circulation. 2022, 145(6): 448-464
Written | Ann
Edit | small ears
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