Obesity effects mimic aging, from DNA damage to cognitive decline

Obesity should be considered premature aging, according to new research from Concordia University in Montreal, Quebec, Canada, and published in the journal Obesity Reviews.

The researchers led by Sylvia Santosa, PhD, RD, looked at how obesity predisposes people to acquiring the kinds of potentially life-altering or life-threatening diseases normally seen in older individuals: compromised genomes, weakened immune systems, decreased cognition, increased chances of developing type 2 diabetes, Alzheimer's disease, cardiovascular disease, cancer, and other illnesses.

Santosa and colleagues reviewed more than 200 papers that looked at obesity's effects, from the level of the cell to tissue to the entire body. They looked at ways obesity ages the body from several different perspectives. Previous studies have linked obesity to premature death, but the researchers note that at the lowest levels inside the human body, obesity is a factor that directly accelerates the mechanisms of aging. For instance, the processes of cell death and the maintenance of healthy cells, apoptosis and autophagy, respectively, that are usually associated with aging.

Studies have shown that obesity-induced apoptosis has been seen in mice hearts, livers, kidneys, neurons, inner ears and retinas. Obesity also inhibits autophagy, which can lead to cancer, cardiovascular disease, type 2 diabetes, and Alzheimer's disease.

At the genetic level, the researchers write that obesity influences several alterations associated with aging. These include the shortening of protective caps found on the ends of chromosomes, called telomeres. Telomeres in patients with obesity can be more than 25 percent shorter than those seen in control patients, according to the study.

The researchers further point out that obesity's effects on cognitive decline, mobility, hypertension, and stress are all similar to those of aging. Pulling out from the cellular level, the researchers said obesity plays a significant role in the body's fight against age-related diseases. Obesity, they said, speeds up the aging of the immune system by targeting different immune cells, and that later weight reduction will not always reverse the process.

The effects of obesity on the immune system, in turn, affect susceptibility to diseases like influenza, which often affects patients with obesity at a higher rate than normal-weight individuals. They are also at higher risk of sarcopenia, a disease usually associated with aging that features a progressive decline in muscle mass and strength,  the researchers said.

Finally, the researchers spelled out how individuals with obesity are more susceptible to diseases closely associated with later-life onset, such as type 2 diabetes, Alzheimer's, and various forms of cancer.

Globally, an estimated 1.9 billion adults and 380 million children are overweight or obese. According to the World Health Organization, more people are dying from being overweight than underweight. In the paper, researchers urge health authorities to rethink their approach to obesity.

Santosa said this research will help people better understand how obesity works and stimulate ideas on how to treat it.

"I'm hoping that these observations will focus our approach to understanding obesity a little more, and at the same time allow us to think of obesity in different ways,” said Santosa in a statement. “We're asking different types of questions than that which have traditionally been asked."