People over 60 with a body mass index (BMI) between 25 and 35, i.e. overweight or obese according to this famous mathematical formula, may present less risk to their health than individuals. with a BMI of less than 25. A Brazilian study by the Federal University of Minas Gerais (Universidade Federal de Minas Gerais) reinforces the current trend of no longer considering BMI as the only reliable method for identifying the influence of weight on health, in some cases it can even be counterproductive.
Abdominal fat greater than BMI
A recurring criticism against the BMI is the difficulty this index has in integrating or identifying abdominal fat, which plays a harmful role in increasing cardiovascular risk. It can create false positives. In other words, a person can have significant abdominal fat but have weak muscles in the legs or arms (therefore with less body weight). This person can then be within the norm in terms of their BMI (from 20 to 25) despite a significant risk to their heart health.
The researchers examined the medical data of 1,606 inhabitants over the age of 60 from the city of Bambú, a municipality located in the southeast of the state of Minas Gerais, Brazil. They observed a surprising result, the inhabitants of this city who had a BMI between 25 and 35 had a lower risk of mortality than those with a BMI below 25.
It’s not that being overweight is advisable in older people, but rather that in the group of people with a BMI of less than 25 there were patients with serious health problems such as weak muscles or osteoporosis. . We know that with age the musculature decreases in volume and therefore loses weight, the bones also see their density drop. You should know that muscle weighs more than fat (for the same volume), so significant muscle loss can greatly lower weight and therefore BMI, creating a false positive. An important point also, in seniors fat naturally tends to be more present in the abdominal area.
An index that is not always reliable with strong limits
Other statistical biases come into play in seniors with the use of BMI, such as the compression of the vertebrae. At this age it is not uncommon to see some people lose up to 5 cm in height, a person can therefore have an appropriate weight while the BMI is over 25 (if the height decreases, the BMI increases mechanically). Other studies, notably American, have issued criticisms in recent years on the use of BMI even among people aged 18 to 65. In these studies, it is also muscle mass that comes up as the main criticism, in particular because women have less muscle mass and there are also differences between ethnic groups that bias the results.
An interesting point raised by various studies is that the practice of sport, regardless of age, reduces mortality. As sports exercise increases muscle mass, we can find individuals with a BMI of more than 25 but in perfect physical shape, in the medical sense of the term (very low statistical risk of dying from a heart attack, for example. ).
That said, the BMI must continue to be used, especially to make comparisons between regions or countries on obesity, this is the case for epidemiological studies. BMI is still recommended in most cases for people aged 18 to 65. However, we must be aware of these limits, especially among athletes.
Other methods of health summer assessment
To conclude, the use of BMI after 60 to diagnose a person’s state of health is therefore no longer appropriate. It is necessary to favor other methods such as the measurement of the waist circumference, the latter should be less than 88 cm in women and 103 cm in men. It is also possible to use the waist-hip circumference formula. By dividing your waist circumference in cm by your hip circumference in cm, a result of less than 0.85 for women or less than 0.90 for men indicates an appropriate weight.