Weighing the Risks: Obesity and Safety

This archived article is from October 2005. Although every effort has been made to make sure the information presented is accurate, please note that it may contain information that is out-of-date.

A Statistics Canada survey released in July 2005 found alarming high obesity rates. Today 23 percent of adult Canadians are obese, compared with 14 percent 25 years ago. Between 1978 and 2004, the overweight/obesity rate of teens aged 12 to 17 more than doubled from 14 percent to 29 percent, while their obesity rate tripled from three percent to nine percent.

Obesity rates in the survey were based on the body mass index (BMI), a measure of body weight relative to height. BMI is calculated by dividing weight in kilograms by height in metres squared. Adults with a BMI of 30 or over are considered obese. For example, a man 1.8 m (5' 10") tall who weighs 95 kg (210 pounds) has a BMI of 30; a woman 1.6 m (5' 4") tall with a weight of 80 kg (175 pounds) also has a BMI of 30. Morbid obesity is defined by a BMI of 40 or over; a woman 1.73 m (5'8") tall who weighs 121.5 kg (270 pounds) has a BMI of 41.

The term bariatrics was created around 1965 to describe the relatively new but growing field of medicine that deals with the causes, prevention and treatment of obesity. Sedentary lifestyles and a high-fat, energy-dense diet are seen as the root causes of the obesity epidemic.

Obesity brings with it a high risk of serious health problems such as diabetes, gallbladder disease, cardiovascular problems (hypertension, stroke and CHD) and certain cancers. Severe obesity is associated with a 12 fold increase in mortality in 25 to 35 year olds compared with lean individuals. According to the Canadian Institute for Health Information, the obese are also three times more likely to need a joint replacement than those of normal weight, and take significantly longer to recover. The Canada Safety Council is concerned that obesity is also a safety issue.

Lifting and Moving

The weight of extremely heavy individuals poses a risk to those who must lift or transfer them, as well as those who need to be moved. Specialized equipment and training are required when moving individuals who are morbidly obese.

Lifting injuries, especially back injuries, are common among health care workers. Lifting an obese patient greatly increases that risk. In an institutional setting, extremely obese patients cannot be lifted in the same way as “larger” adults. Bariatric lifting and transfer equipment is needed, as well as wheel chairs, beds and commodes designed for people hundreds of pounds overweight. This means health care facilities must purchase specialized products and invest in worker training to assure the safety of both the patient and the worker.

Emergency responders face a challenge when they need to move a corpulent person. Due to limited mobility, obese persons are more likely to require extra help. Bariatric equipment and added personnel must be readily available to carry them. The maximum load for standard stretchers is around 295 kg (650 pounds). Morbidly obese casualties require Large Body Surface (LBS) stretchers. These specialized stretchers extend the width of the stretcher, but do not allow the load limit to be exceeded. They are still relatively uncommon in Canadian ambulance services.

In a fire, anyone unable to fit into a normal escape route such as a stairway or window may have few alternatives. If the fire is in a multi-story building, those too big to move quickly on their own will find it hard to get out, with elevators out of service and crowds rushing to escape.

A natural disaster can endanger large numbers of people. Due to the sheer magnitude of a major catastrophe, rescuers may be unable to move the very obese away from the danger.


A 2002 study looked at more than 26,000 people who had been involved in car crashes. It found that people with a BMI of 35 to 39 are over twice as likely to die in a crash as people with BMIs of about 20. People who weigh between 100 and 119 kg (242 to 262 pounds) are almost two-and-a-half times as likely to die in a crash as people weighing less than 60 kg (132 pounds), but obesity is a more important factor than body weight alone. Reasons for the higher risk of injury or death include: the sheer force of the weight; underlying health problems that hinder recovery; and the difficulty of extricating an obese person from a crumpled vehicle.

Car dealers provide free seat-belt extenders that fit the restraint to a larger body, because standard seat-belts are not designed for obese people. In a crash, a seat-belt must grip bone: hip, sternum, shoulder, ribs. Fat does not act as a safety cushion, and can even be harmful. It acts like air, and creates a gap between the belt and the bones that can allow the person to slide from behind the seat-belt during rollovers. In a crash, the belt snaps back through that gap and slams into the skeleton or organs as they hurtle forward. If the seat-belt does not quickly encounter the pelvis, it can damage internal organs.

Automakers helped fund the Civilian American and European Surface Anthropometry Resource (CAESAR), an international private-public project, which has produced digital 3-D images of thousands of men and women of all sizes. Engineers can electronically place the scanned images behind the wheel or in the passenger seats of their vehicles.

The CAESAR database enables vehicle manufacturers to make allowance for the comfort and safety of portly drivers and passengers. Seats in some vehicles now have longer rails to slide on, allowing more space between the driver and the steering wheel. Adjustable pedals allow drivers with large midsections to move well back from the steering wheel.

It has also been suggested that heavier crash-test dummies should be used when certifying cars as safe to drive. Although safety regulations only require the use of 50th percentile male test dummies, virtually all car manufac­turers already do crash tests with 95th percentile dummies (6'2" and 223 pounds, or about 188 cm and 100 kg).

Prevention a Priority

The World Health Organization, in its Global Strategy on Diet, Physical Activity and Health, identifies obesity as an international priority. In 1995, an estimated 200 million adults worldwide were obese. By 2000, the number of obese adults was over 300 million. This obesity epidemic goes far beyond developed countries; paradoxically it co-exists with under-nutrition.

An International Task Force on Obesity, part of the International Association for the Study of Obesity, is looking at four areas of concern:

  • Prevention - to halt the drift from overweight into obesity.
  • Childhood obesity - to assess the problem and suggest solutions.
  • Management - to develop better guidelines to deal with weight.
  • Economic costs - to assess the financial burden of obesity.

Many countries have already set up national initiatives to address the above issues. In 2005, Health Canada established a Canadian Obesity Network to address the problem through education, public information and research.

The Canada Safety Council is a longstanding partner in encouraging workplace programs that promote healthy eating and physical activity. Stairway to Health is an on-line resource that encourages stair use as a way to build physical activity into daily living, focusing on the workplace. An environmental scan of workplace healthy living policies was initiated in 2005 in conjunction with Health Canada’s objective to reduce obesity by 10 percent.


* Mock C et al. The relationship between body weight and risk of death and serious injury in motor vehicle crashes. Accident Analysis and Prevention, 34: 221-228, 2002.