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The weight of an individual is not enough to determine whether they are obese or overweight. Various measures are used to provide additional information and to predict the impact of obesity on health.

Body mass index (BMI). According to WHO, it is the most useful tool, although approximate, to measure overweight and obesity in adults. This index is calculated by dividing a person’s weight in kilograms (kg) by the square of their height in meters (m2). Overweight refers to a BMI between 25 and 29.9; obesity indicates a BMI higher than or equal to 30 and morbid obesity means a BMI higher than or equal to 40. A healthy weight corresponds to a BMI between 18.5 and 25.

Waist circumference. It is often used as a supplement to the BMI and it can detect an excess of fat in the abdomen. It is abdominal obesity when the waist circumference is greater than 88 cm (34.5 in.) in women and 102 cm (40 in.) in men. In this case, the health risks (diabetes, hypertension, dyslipidemia, cardiovascular disease, etc.) increase considerably.

Waist circumference and waist–hip ratio. This measurement provides an even more accurate idea of the distribution of body fat. The ratio is considered high when the result is greater than 1 in men and greater than 0.85 in women. Researchers are developing new tools to measure the excess of body fat. One of these tools, called fat mass index, is based on the measurement of the circumference and size of the hips. However, this tool still has not provided conclusive results and, for this reason, it is not yet used in medicine.
A blood analysis, the lipid profile in particular, provides the doctor with valuable information concerning the assessment of risk factors in the development of diseases.


The proportion of obese individuals has increased over the last 30 years. According to the World Health Organization (WHO), the prevalence of obesity has reached epidemic proportions worldwide. There is an increase
in the average weight in all age groups and all socio-economic classes.


Globally, 1.5 billion adults aged 20 and over are overweight and at least 500 million of them are obese.
Developing countries are not spared:
In Canada, according to the latest data, 36% of adults are overweight (BMI > 25) and 25% are obese (BMI > 30).
In the US, about one third of people aged 20 and over is obese and another third is overweight.
In France, approximately 15% of the adult population is obese and nearly a third is overweight.


When trying to understand why obesity is so prevalent, it appears that the causes are multiple and not solely based on the individual. The government, municipalities, schools, the agribusiness sector, etc., also bear some responsibility in creating obesogenic environments.
The term “obesogenic environment” is used to describe a way of life which contributes to obesity:
Access to food rich in fat, salt and sugar, high in calories and low in nutrients (junk food)
Sedentary and stressful lifestyle
Living environment not conducive to active transportation, such as walking or cycling.
This obesogenic environment has become a norm in many industrialized countries and more common in developing countries as the population adopts a western lifestyle.
Individuals whose genetic makeup make them more likely to gain weight are more susceptible to the obesogenic environment.
However, the susceptibility linked to genes can not lead to obesity by itself.


Obesity can increase the risk of chronic diseases. Health problems may begin to manifest after about 10 years of being overweight.


Type 2 diabetes (90% of type 2 diabetics are obese or overweight)
Gallstones and other gallbladder problems
Dyslipidemia (abnormal levels of lipids in the blood)
Shortness of breath and sweating
Sleep apnea


Cardiovascular problems: coronary heart disease, cerebrovascular accident (stroke), heart failure, cardiac arrhythmia Osteoarthritis of the knee Gout. Generally, obese individuals have a lower quality of life as they age and a shorter life expectancy than those with a healthy weight.

Moreover, health professionals predict that today’s youth will be the first generation of children whose life expectancy does not exceed that of their parents, mainly due to the progressive growth of childhood obesity.

Finally, obesity can become a psychological burden. Some people might feel excluded from society due to the beauty criteria imposed by the fashion industry and by the media.

Given the difficulty in losing excess weight, other individuals may live in great distress or anxiety which can lead to depression.


Obesity is characterized by “abnormal or excessive fat accumulation that may impair health”. Essentially, obesity is the result of an excessive intake of calories for several years when compared with physical activity practised. A distinction should be made between obesity and overweight. The latter also refers to an excessive amount of body weight but it is less important. Morbid obesity is an advanced form of obesity. It is considered to be so harmful to health that it may shorten the lifespan by 8 to 10 years.