Obese older people who sleep badly have less muscle strength and mass in their legs and arms, as well as more body fat and more symptoms of anxiety and depression than those who sleep well, according to a study conducted by researchers at the University of São Paulo (USP) in Brazil. An article on the study is published in the journal Scientific Reports.

The number of obese older people has increased worldwide in recent decades. In Brazil, the prevalence of overweight in people aged 60 and more rose from 53.7% in 2006 to 60.4% in 2019 (an increase averaging 1.16% per year), while obesity rates rose from 16.1% to 20.8% (2.34% per year), according to a study (in Portuguese) that analyzed data from the Health Ministry's national telephone surveillance survey on risk factors for chronic diseases (Vigitel).

Overweight rose most among men, and also among people of both sexes aged 80 and over. Obesity rose most among both men and women aged 70-79.

"We have a perfect storm: aging of the population and rising obesity among the elderly, many of whom frequently suffer from poor sleep quality, loss of muscle strength and mass, and mental health problems. It's also important to bear in mind that sleep quality is a critical health factor for the general population," said Hamilton Roschel, last author of the study described in Scientific Reports. He is a nutritionist, clinical exercise physiologist and professor at the University of São Paulo's Medical School (FM-USP).

To investigate the association between sleep quality and quantitative and qualitative parameters of mental and physical health in obese older people, the researchers asked 95 obese men and women aged 65 or more to complete a sleep quality questionnaire (PSQI) and a general health questionnaire focusing on anxiety, depression and quality of life. They were divided into good sleepers (46) and bad sleepers (49) in accordance with their PSQI score. Body composition and handgrip strength were also measured.

"We found that the poor sleepers had worse physical and mental health, with less vitality, more muscle pain, and impaired physical and mental functions. They had more body fat, less lean fat, and less muscle strength. Their anxiety, depression and quality of life scores were also worse," Roschel said.

Impact on health during aging

As the researchers note in the article, their findings serve as an alert to the importance of sleep quality to the overall health of elderly people, especially if they are obese. The presence of obesity during aging has an impact on several physiological processes, such as anabolic response and glucose metabolism, and also exacerbates the adverse effects of aging on sleep disorders.

"Confirmation that obese older people are at higher risk of worse outcomes can help improve the screening of patients who use the SUS [Brazil's national health service], so they get the right care and avoid general deterioration of their health," Roschel said.

In the coming months, the group will publish the findings of a complementary longitudinal study involving lifestyle therapies designed to prevent negative outcomes in body composition such as loss of muscle mass with body fat gain, and metabolic disorders such as hyperglycemia.

More information: Rafael Genario et al, Sleep quality is a predictor of muscle mass, strength, quality of life, anxiety and depression in older adults with obesity, Scientific Reports (2023). DOI: 10.1038/s41598-023-37921-4