Poor muscle health is common in people living with obesity – and increases the risk of an early death, according to a study to be presented at the European Congress on Obesity (ECO) in Venice, Italy (12-15 May).

Individuals with adverse muscle composition were up to three times more likely to die during the course of the study than those with healthy muscles, the Swedish study of people in the UK concluded.

“We found that just by looking at muscle composition we can predict which individuals with obesity are most likely to die during the next few years,” said lead researcher Dr Jennifer Linge, of AMRA Medical, a health informatics company in Linköping, Sweden.

Weight loss is increasingly recommended in the management of chronic conditions such as type 2 diabetes and cardiovascular disease and weight loss drugs are allowing people to lose larger amounts of weight than in the past.

However, with drugs now achieving weight loss close to the magnitudes seen with surgery, the concern for potential adverse effects on muscle health, such as significant loss of muscle mass and reduced mobility, is growing.

“Research has shown that although individuals with obesity have more muscle mass, their muscles are, in general, relatively weaker,” said Dr Linge. “They also have lower muscle quality, as well as reduced mobility and function.

“Accurate assessment of muscle composition, assessing both quantity and quality of the muscles during evaluation these treatments will teach us whether significant and rapid weight loss is safe – especially for the more vulnerable patients, such as those with sarcopenic obesity or of older age.”

To find out more, Dr Linge and colleagues used AMRA® Researcher (software that provides body composition measurements from MRI scans) to analyse scans from 56,109 participants in the UK Biobank study.

Muscle volume (muscle quantity) and muscle fat (indicating muscle quality) were quantified and a personalised muscle volume z-score (an indication of how their muscle volume compares to the average for their sex and body size) was calculated.

Participants were partitioned into four groups according to whether they had normal muscle composition, high muscle fat only, low muscle volume z-score only or adverse muscle composition (both high muscle fat and low muscle volume z-score).

The participants were followed-up for an average of 3.9 years, during which time 174 died.  The most common causes of death were ischaemic disease (coronary heart disease) and hypertensive disease (primary hypertension, hypertensive heart disease and hypertensive renal disease).

While having low muscle volume z-score or high muscle fat alone was not significantly associated with a higher risk from death from any cause, adverse muscle composition (having both low muscle volume z-score and high muscle fat) was. This underlines the importance of assessing the amount of fat in muscle, as well as muscle volume, when evaluating muscle health, say the researchers.