Reaching the age of 122, like the Frenchwoman Jeanne Calment (1875-1997), seems practically unthinkable, and even scary. But the truth is that the figures we have in relation to demographic aging are alarming. By 2050, the population over 80 years old is expected to triple. In Spain, one of the oldest countries in the world, it is expected that upon reaching the current retirement age, 65 years, its inhabitants will have a life expectancy of 28 more years.
This constant increase in longevity represents a challenge that encompasses economic, social, structural, political, medical and scientific factors. So much so that, from 2016 to 2020, the WHO established a “global strategy and action plan for aging and health.”
The United Nations also declared the “Decade of Healthy Aging” from 2020 to 2030, a kind of collaborative and global platform aimed at facing this reality and ensuring continued care for the elderly. In part, because we know that temporary and palliative health care is no longer sufficient to meet the needs of the senior population.
Maintaining good health in later stages of life is also affected by the risks derived from age-related metabolic diseases. Unfortunately, the figures we have in relation to obesity are also worrying: it is expected that, in a few years, one in two adults will be obese.
This discouraging scenario is aggravated by the fact that excess body fat increases the chances of suffering from comorbidities – associated ailments – such as cardiovascular disease, diabetes and cancer. It is, therefore, unquestionable that the accelerated pace of aging, together with the growth of obesity, represents a serious threat to global health.
At this meeting point, the coexistence of obesity and sarcopenia – the loss of muscle mass and strength characteristic of older people – takes on special relevance. It is called sarcopenic obesity and it increases the chances of older people suffering from metabolic diseases, comorbidities, falls, disabilities, psychological illnesses and death.
A group of researchers from the Madrid Institute of Advanced Studies IMDEA Food and the National Institute of Aging in the United States have published a collaborative opinion article indicating the fundamental aspects that will allow progress in interdisciplinary research on aging and obesity.
One of the fundamental messages is that the relationship of aging and mortality with obesity and the distribution of body fat is not simple, much less linear. In fact, we know that it changes depending on the location of adipose tissue or body fat.
For example, increased visceral adiposity (in the abdomen) is a strong indicator of mortality. On the contrary, an increase in subcutaneous blood is associated with a decreased risk. As for intermuscular adipose tissue, which also increases with age, it is linked to a greater risk of death.
Another determining factor is age. Although obesity reduces the life expectancy of young individuals and accelerates premature aging, we know that maintaining body fat at older ages predicts increased survival. And likewise, unintentional weight loss in older people is linked to an increased risk of dying.
In our article we wanted to show that there are no specific studies that directly determine the effect of age on obesity. Furthermore, we encourage the scientific community and institutions to develop work that allows us to individually follow this pathology over time, in such a way that allows us to clarify the ins and outs of this dynamic relationship.
From a biological and physiological point of view, we have known for a decade that certain cellular, molecular and neuroendocrine processes modulate aging processes. They are known as the hallmarks of aging and have been recently revised.
We also know that many of these processes are similar in obesity, such as damage from oxidative stress, inflammation or deregulation of cell recycling processes or autophagy. The existence of these common mechanisms opens the door to thinking that strategies used to combat obesity can in turn slow down aging and preserve health, or vice versa.
In this sense, changes in eating habits and the practice of physical exercise become the first line of action. Interventions that reduce energy intake, such as caloric restriction or intermittent fasting, have demonstrated their potential to extend lifespan in the majority of organisms that have been experimented with. It is very interesting to note that these physiological benefits have been observed even in the absence of weight loss or despite gaining it back.
In this sense, losing kilos is not framed as the primary objective in the research we carry out in the area of ??aging. In fact, we know that certain anti-aging interventions are capable of increasing life expectancy in animals when they are fed high-fat diets, but that the same does not seem to occur when the dietary context is standard. These investigations once again reveal the intricate relationship that exists between both processes.
That complexity is also seen when exercise is added to the equation. Although physical activity is generally associated with increased longevity, multiple animal studies have not been able to connect both parameters in a statistically significant way. In any case, the idea of ??“every activity and at any age adds up” is what has to predominate. Its health benefits are unquestionable.
In addition to lifestyle changes, there are various pharmacological treatments to combat obesity. Among them, drugs that mimic the action of a hormone released by the intestine, known as GLP-1, are demonstrating admirable effectiveness.
Recent research suggests that treatment with these drugs modulates the hallmarks of aging, even reversing certain brain aging processes in animals. However, to date they have not been shown to increase longevity.
Alberto Díaz-Ruiz has a PhD in Science from the University of Córdoba, specialized in the areas of metabolism, aging and cancer. He is Group Head, Laboratory of Cellular and Molecular Gerontology, at the IMDEA Food Institute, in Madrid.
This article was originally published on The Conversation.