A research group from Japan’s health ministry estimates that 9.14 million people nationwide have “hidden” metabolic syndrome, displaying multiple problems such as high blood pressure and high blood sugar despite not being overweight.

Although efforts to combat metabolic syndrome currently focus on obesity, the build-up of metabolic problems such as high blood pressure and hyperlipidemia can increase the risk of heart disease, even if a person is not overweight. Hyperlipidemia is the presence of excess fat or lipids in the blood.

The research group will develop guidelines for diagnosing hidden metabolic syndrome and improving one’s lifestyle by March next year.

Led by professor Hiroshi Shimokata at Nagoya University of Arts and Sciences, the research group analyzed the results of a survey conducted by the National Center for Geriatrics and Gerontology from 1997 to 2012 on the health of about 4,000 men and women aged 40 to 79.

The data showed that 10.9 percent of men and 13.6 percent of women suffered from at least two out of three health problems — high blood pressure, high blood sugar and hyperlipidemia — despite having a body mass index (BMI) of less than 25 and an abdominal circumference lower than what is usually linked to metabolic syndrome.

Based on these figures, the group estimated the national incidence of hidden metabolic syndrome at 3.8 million people for men and 5.34 million for women. It also estimated that 9.71 million are suffering from metabolic syndrome.

Patients with hidden metabolic syndrome are 23 percent more likely to develop heart disease than their healthy counterparts. Those with metabolic syndrome are 45 percent more likely.

Many Japanese people do not produce enough blood sugar-reducing insulin, putting them at greater risk of diabetes even if they are thin. Bad lifestyle habits, such as a lack of regular exercise, skipping breakfast and eating too quickly, also increase the risk of developing hidden metabolic syndrome.

If no preventive measures are taken, the number of sufferers is expected to increase to 10.14 million in 10 years and to 10.42 million in 20 years.

Comparing 4,000 people of the same age and gender in the survey, it was found that those who walked more than 5,500 steps a day improved their metabolism. Intake of calcium and protein, as well as the unsaturated fatty acid abundant in blue-backed fish such as mackerel, was also found to be effective.

“Many Japanese people have problems with their metabolism despite not being overweight,” Shimokata said. “Efforts to combat obesity are moving forward, but the fight against hidden metabolic syndrome has been left unattended. We also need measures to prevent older people from becoming bedridden.”

Metabolic syndrome

A condition in which excess internal fat results in a build-up of metabolic problems, increasing the risk of lifestyle-related illnesses such as heart disease and stroke. In fiscal 2008, the government began a campaign of special metabolic examinations for people aged 40 to 74, aiming to prevent lifestyle-related illnesses and reduce medical expenses.