Obesity is defined as an excess of body fat resulting in a significant increase in weight and which can have negative effects on the health and well-being of the individual. Since 1997, it has been recognized as a chronic disease by the World Health Organization (WHO).

Today we can talk of a global epidemic attacking the youngest among us. In Canada, the obesity rate among children aged 6 to 17 has in fact gone from 6% in 1978 to 13% in 2014. Although stabilized, this percentage has not decreased over the past ten years, so nearly one in three Canadian children is currently overweight or obese.

Globally, according to the WHO, more than 1.9 billion adults (or 26%) were overweight and, among them, there were 650 million obese (9%).

These numbers have almost tripled since 1975! Similar findings in Quebec, where the prevalence of adult obesity has doubled over the past 25 years. In 2013, according to health authorities, it affected 20% of Quebec men and 16% of Quebec women. Despite a relative stabilization, the projections of the National Institute of Public Health of Quebec (INSPQ) are very worrying. By 2030, no less than one in four men and one in five women could be affected by this disease.


Globally, overweight and obesity are now associated with more deaths than underweight caused by starvation or disease. This is an unprecedented situation that affects all high and middle-income countries like Canada. This mortality is explained by the fact that obesity is a complex risk factor for chronic diseases and is associated with a number of socio-economic determinants.

A challenge

Obesity is now a public health issue as important as smoking since it leads to an increase in coronary and cardiovascular diseases, several cancers, type 2 diabetes, and a number of other complications (joint problems, breathing difficulties, sleep disturbances, etc.). Research has shown that in 2011, the number of medical consultations for obese people was 13% higher than for people of normal weight and they were 94% more likely to spend the night in the hospital!

1 Source: Obésité : prévention et prise en charge de l’ épidémie mondiale, OMS, Genève, 1997.
2 Source: Poids santé chez les enfants au Canada, labo de données de l’Agence de la santé publique du Canada.
3 Source: Vers un Canada plus sain, rapport d’étape 2017, Réseau pancan. de santé publique.
4 Source: Obésité et surpoids, OMS, octobre 2017.
5 Source: Indicateurs synthèses sur l’obésité, INSPQ, modifié le 4 avril 2017.
6 Source: Embonpoint et obésité chez les enfants au Canada, Santé publique Canada, 2017.
7 Source: Health-Related Quality of Life of Severely Obese Children and Adolescents, JAMA, avril 2003.
8 Voir Chirurgie de l’obésité et risque de suicide : « Le suivi psychologique n’est pas toujours respecté », Sciences et Avenir, octobre 2015.
9 Source: Les conséquences économiques associées à l’obésité et à l’embonpoint au Québec : les coût liés à l’hospitalisation et aux consultations médicales, INSPQ, mise à jour 2016.
10 Voir Le poids économique de l’obésité, Radio Canada, octobre 2015.
12 Source: Enquête sur la santé dans les collectivités canadiennes (ESCC) citée dans Obésité et travail, Statistiques Canada, novembre 2015.


Main causes

The rise in the rate of overweight in recent decades is undoubtedly explained by changes in our lifestyle. Bad eating habits, lack of physical exercise due to sedentary work, cars and television, stress and sleep disorders caused by work and technology are the most pointed culprits. But especially important genetic factors are also at playIn reality, obesity is a complex multifactor disease.

Genetic predisposition

There are many scientific studies that have demonstrated a clear statistical correlation between genetic inheritance and obesity. Thus, children born to “normal” or thin parents have less than a one in ten chances of developing the disease. If one of the parents is obese, the risk increases to four chances out of ten and it reaches eight chances out of ten if both parents are obese.

A few isolated cases are caused by a single defective gene altering the metabolism from birth and almost certainly leading to severe obesity. However, scientists have identified tens of genes that can induce a certain predisposition to the disease. These genetic particularities can combine and be aggravated by other lifestyle factors.

Overall, it is currently estimated that the role of heredity in obesity is around 40 to 50%. Gene therapies are being studied to cure some cases linked to a single genetic mutation. However, it is still far too early to fully understand and, even more so, be able to treat all the genetic factors associated with the most common cases..

Lack of exercice

Lack of exercise has a definite impact on the obesity rate, either in addition to genetic factors, or because of age or other situational factors. As soon as our body receives more energy than it consumes, it transforms the excess food into fat that it stores in adipose tissue. In order not to gain or lose weight, it is therefore necessary to maintain the balance between the energy that we absorb and that which we spend.

To maintain optimal health, adults aged 18 to 64 should get at least 150 minutes of moderate-to-vigorous intensity physical activity per week. Unfortunately, only 15% of Canadians meet or exceed this minimum quota.

Bad eating habits

Although famines continue to hit certain regions of the world hard, North America is going through an era of nutritional overabundance linked to the industrialization of the agri-food sector.

Encouraged by marketing and advertising, this overabundance translates into excessive overconsumption.

  • The continuous snacking of salty and sweet products rich in simple carbohydrates and fat does not produce a satiety effect. Result: we want more.
  • The wide variety of food products available on the market also disrupts our satiety mechanism. Seduced by the appeal of new flavors, we no longer necessarily stop eating when our energy needs are met. Result: we eat too much.
  • The trend for “light” products is misleading. These foods low in fat but also exceptionally low in protein and loaded with sweeteners create a real “addiction”. Result: we always consume more!

Psychological and pathological factors

It is common for people suffering from obesity to have had a childhood or adolescence marked by socio-emotional deficiencies and psychic traumas leading, a few years later, to eating disorders. These cannot be permanently eliminated without addressing their psychological causes.

Finally, as we have previously seen, severe obesity is often linked to genetic factors, but also to complex pathologies such as metabolic or hormonal disorders. The combination of all these factors makes losing weight and maintaining it extremely difficult for people struggling with the acute stages of this disease.


Understanding your BMI


Type I

>With a BMI between 30 and 35, one faces a substantial risk of developing health problems. It is necessary to be followed by a doctor and to closely monitor your lifestyle in order to lose weight or, at the very least, to avoid slipping into a more advanced state of obesity.

There is no shortage of risk factors that can aggravate the situation. For example, stress caused by misfortune, family breakdown, bereavement or job loss is often a determining factor in the transition from class I to class II. A major change in lifestyle can be too — a change in diet caused by moving, for example, or quitting smoking without adequate mitigation measures. Finally, taking certain medications can also have a side effect of rapid and excessive weight gain that will be exceedingly difficult to reverse later.

Your healthcare professional is there for you.


Type II

With a BMI between 35 and 40, we enter the field of severe obesity, with an overweight of one hundred pounds or more. In Quebec, the number of people exceeding this threshold is estimated at 3% of the population (i.e., more than 200,000 people). Medical follow-up is essential in order to reduce and even preferably eliminate this excessive fat mass threatening our balance, our health and perhaps even, in the long term, our survival. The family, social and professional environment also has a critical role to play in supporting, encouraging, and accompanying.

Here again, significant work on factors related to lifestyle (nutrition, exercise, and psychological support) will be at the heart of the therapeutic course in order to reduce weight by at least 10%. The ultimate goal is to change one’s behavior in order to regain control and reverse the trend of being overweight.

However, some patients have metabolic complications that substantially increase the likelihood of type 2 diabetes and cardiovascular disease. In this case, the risks associated with these complications may justify the use of bariatric surgery, more or less urgently, depending on the patient’s condition.


Type III Obesity

With a BMI equal to or greater than 40.

The list of high-risk complications associated with it, is long:

  • Type 2 diabetes and abnormal lipidemia.
  • Hypertension and cardiovascular diseases.
  • Problems related to the liver, pancreas, and gallbladder.
  • Musculoskeletal problems related to the joints.
  • Problems related to the reproductive system (menstruation, infertility, impotence).
  • Obstructive sleep apnea.
  • Certain types of cancer, in particular digestive or hormone dependent.

The disease is then considered irreversible and bariatric surgery is generally the only possible option to minimize the risks and restore a good quality of life. Exercise no longer allows you to lose weight, but the bariatric course requires good behavioral and nutritional preparation.

1 Source: Hôpital du Sacré-Coeur de Montréal.
2 To find more on the differences between severe obesity and morbid obesity Banque de dépannage linguistique of the OQLF.
3 Source: Hôpital du Sacré-Coeur de Montréal.
4 Voir 11 types de cancer corrélés au surpoids et l’obésité?Sciences et Avenir, avril 2017.
5 Source to not quote: obesite-severe-lexercice-physique-ny-peut-rien-ou-presqueLe Soleil, juin 2014.