SFU research shows that different ethnic groups have increased health risks from obesity

Kinesiology professor Scott Lear shows the control panel for the DEXA x-ray machine in his lab at SFU Vancouver where he examines over 150 people a month for obesity related studies.

November 05, 2008

A small pile of neatly flattened chocolate bar wrappers and empty potato chip bags sit on the corner of Scott Lear’s desk. He is copying their listed ingredients as part of an ambitious 18 country study on diet and obesity. The project is based in Hamilton, Ontario at McMaster University but Lear runs the Vancouver branch of the research. The SFU Kinesiologist specializes in obesity and its relation to disease in Asians compared to Europeans and Aboriginals. His lab, located at SFU’s Vancouver campus, processes about 150 people every month and they are discovering significant differences.

Lear did eat the candy and chips but he is not overweight. He cycles to work every day and often wears a pedometer. “At lunch time I check it to see if I have taken enough steps,” he says. “If my step count is low, it forces me out for a mid-day walk.” His wife has a pedometer too, and sometimes they compare steps at the end of the day. Weight gain, according to Lear, is a function of life-style more than any other factor, so he tries to incorporate exercise into his daily routine. “People can be fat and fit,” says Lear. Sumo wrestlers are tremendously fat but they exercise a lot each day. It’s only in retirement that they come down with diseases related to obesity.

Lear’s interest in obesity and health began about ten years ago when Jiri Frolich, his PhD thesis advisor at UBC introduced him to Laird Birmingham, a doctor at St. Paul’s Hospital in Vancouver. Birmingham had noticed that overweight people of Asian origin seemed to be more susceptible to diabetes and heart disease than Europeans, but he had no scientific proof. Obesity is on the increase in China and India as those countries prosper economically, but overweight people there have been rare until recently, so no studies had been done. Lear says, “India and China now have the strange situation of dealing with people who are malnourished and over nourished, something not as common in developed countries.”

Over a period of ten years with a series of grants from the Canadian Institutes of Health Research, Lear has shown that Asians are indeed at higher risk for diseases related to obesity. He compared four groups of 200 each: South Asians, Chinese, Canadian Aboriginals, and Europeans, with roughly equal numbers of thin, average, and overweight individuals of both sexes. It turns out that Chinese and South Asians have relatively more abdominal visceral adipose tissue (VAT), a type of fat that forms inside the abdomen around organs such as the liver and kidneys, as opposed to subcutaneous fat, the kind you can see and feel just under the skin. However, no significant differences were noticed between Aboriginals and Europeans.

There was no difference in the relation between waist circumference or body mass index (BMI, a ratio of a person’s height and weight) and risk of heart disease when comparing Aboriginal peoples and Europeans. But compared with Europeans, body fat percentage was higher for a given BMI in South Asians, whereas VAT was higher for a given waist circumference in both Chinese and South Asian groups. According to Lear, VAT is a better indicator because it’s more associated with risk of heart disease. “Think of fat as an organ,” says Lear. Fat cells produce hormones such as adiponectin that regulate fat storage and the body’s production of insulin. Thinner people produce more adiponectin. Scientists are not sure why or how the hormone works, but it can be protective for heart disease.

“Most people see obesity as an individual thing. It’s the person’s fault,” says Lear. But that is not the case. Obesity is a societal responsibility. According to Lear, government and industry need to recognize this and make changes. Japan is regulating body size and issuing fines to businesses with overweight staff. “Society must change,” says Lear. “I need a place for my sweaty clothes, a shower, and a safe place for my bike.” He also points out that it takes time. No diet yields results overnight. “It took 20 years to get fat, so plan to invest another 20 or 30 years to reverse it,” he says. Contact: salear@sfu.ca.

Dr. Lear is one of three scientists participating in a Café Scientifique to be held at the Vancouver Public Library Central Branch on Nov 19, at 6:00pm. Find out more at our events page.