Being overweight is one of the risk factors for prediabetes and type 2 diabetes. In Canada, almost 60% of adults are overweight or obese.

One of the important links between obesity and diabetes is insulin resistance; namely, the reduced capacity of insulin to get glucose (sugar) into the cells and stop glucose production by the liver. Insulin resistance is very prevalent in the obese. However, you can be thin and insulin resistant and, conversely, obese and sensitive to insulin.

When a person is overweight, a gradual weight loss of 5% to 10% is sufficient to see health benefits:

  • better blood glucose (sugar) control and improved blood pressure (hypertension)
  • improved lipid profile (blood cholesterol and triglycerides)
  • reduced risk of cardiovascular disease

Definition of overweight and obesity

Health care professionals use certain indicators to determine the health risks for individuals, including the BMI (Body Mass Index) and waist circumference. It is important to rely on more than one indicator to consider the distribution of body fat.

Body Mass Index (BMI)

The BMI is the ratio of weight to height squared:

BMI = Weight (kg) / Height (m2)

The BMI indicates the risk of developing a chronic disease like diabetes. It is used for people 18 and older.

This indicator can be inaccurate for athletes or very muscular people, whose BMI tends to be overestimated.

If your BMI is…You could be …
18.4 or lessunderweight
18.5 to 24.9a healthy weight*
25 to 29.9overweight
30 or moreobese

*If you are 65 or older, the “healthy weight” band can start slightly higher than 18.5 and go up to a value in the “overweight” band.

Waist circumference

In addition to the BMI, waist circumference can determine how fat is distributed on the body. Abdominal fat is associated with such health risks as heart disease and diabetes. This type of fat is more harmful because it surrounds the vital organs.

A decrease in waist circumference does more to improve health than weight loss on the scales.

Waist measurements representing a high health risk

Country of originMaleFemale
Canada, United States> ou = 102 cm> ou =  88 cm
Europe, Sub-Saharan Africa, Middle East, Mediterranean> ou =  94 cm> ou =  80 cm
Asia, Japan, Central and South America> ou =  90 cm> ou =  80 cm
Source: Canadian Diabetes Association 2013 Clinical Practice Guidelines for the Prevention and Treatment of Diabetes in Canada

Research and text: Cynthia Chaput, Dt.P., Dietitian

June 2014


Garrel, D., (2006) “Comment l’obésité cause le diabète et que peut-on y faire ?” Plein Soleil, Autumn 2006, pp. 25-26.

Goldenberg, R. & Punthakee, Z., “Definition, Classification and Diagnosis of Diabetes, Prediabetes and Metabolic Syndrome,” Canadian Diabetes Association 2013 Clinical Practice Guidelines for the Prevention and Treatment of Diabetes in Canada (Canadian Journal of Diabetes, vol. 37, pp. S8-S11), Canadian Diabetes Association.

Ordre professionnel des diététistes du Québec, (2000) “Obésité et contrôle du poids,” Manuel de nutrition clinique.

Maintaining your weight depends on the balance between your energy intake (food and beverages consumed) and your energy expenditure (the body’s vital functions, daily activities, sports, etc.).

A multitude of other factors can influence the intake and expenditure of energy:

  • Quitting smoking
  • Medication that stimulates the appetite
  • An injury or illness that limits physical activity
  • The emotional aspect of eating
  • Etc.

Finally, other factors can affect this balance and cause some people to have more trouble losing weight:

  • A person’s basic metabolism (the energy expended on the body’s vital functions)
  • Heredity
  • Restrictive weight-loss diets done repeatedly
  • Etc.

There is no “ideal” weight, just an optimal, natural weight at which each person is healthy.

Healthy and sustainable weight loss

Healthy weight management is a function of good, long-term lifestyle habits: a balanced diet, regular exercise, adequate sleep, stress management.

Changing ingrained lifestyle habits is often a major challenge. The important thing is to be kind to yourself: don’t expect to lose in two weeks the weight gained over several months or years. You should look at weight loss as a long term investment. Changes in lifestyle habits that endure over time are the ones that will be most beneficial and help you maintain a lower weight.

To increase your chances of success, focus on the multiple benefits from weight loss: the feeling of well-being, better glycemic control, healthier lifestyle habits instilled in your children or loved ones, etc.

Learn to set goals using the S.M.A.R.T. method.

About weight-loss diets …

Popular weight-loss diets are usually based on one of these principles: restrictions and deprivation, the complete elimination of a group or type of food; or the need to buy products whose effectiveness has rarely been scientifically proven.

Did you know?

  • 85% to 95% of people who lose weight on a weight-loss diet put it all back within the next 5 years (INSPQ*, 2008).
  • The reason why strict weight-loos diets fail is not because of a lack of will on the part of the dieter: it’s the restrictive nature of the diet itself.
  • Forbidden foods lead to frustration and increase the desire to eat them, which often leads to over-consumption after the diet is over. This may partly explain why the weight returns (the yo-yo effect).
  • When your body is in “famine” mode, it adapts by burning fewer calories for its core functions, resulting in a recovery of the weight lost when you return to your old eating habits.
  • Diets that eliminate a food group can lead to nutritional deficiencies.
  • Weight-loss products are expensive and can be dangerous.

* Institut national de santé publique du Québec

Research and text: Cynthia Chaput, Dt.P., Dietitian

June 2014


ÉquiLibre. Pourquoi les diètes ne fonctionnent pas? (French only.) (Web page consulted on May 23, 2014).

Ordre professionnel des diététistes du Québec, (2000) “Obésité et contrôle du poids,” Manuel de nutrition clinique. (French only.)

Research indicates that when people aren’t allowed to get a full night’s sleep, they tend to eat more than usual the next day. Sleep is a period of hormone regulation: for hormones like leptin, which sends signals of satiety to the brain; and ghrelin, which stimulates the feeling of hunger. Lack of sleep also compromises a person’s exercise routine.

For more information on how to adopt healthy lifestyle habits, see our sections on dietphysical activity and stress management.

Research and text: Cynthia Chaput, Dt.P., Dietitian

June 2014


Institut national de santé publique du Québec, “Sleep and Weight Problems: A New Avenue for Intervention?,” TOPO, Issue 4, January, 2013.  (Downloadable PDF.)