Defining and Measuring Obesity

There is little doubt about the link between obesity and diabetes.  Overeating particular types of food has been established by medical researchers as the main cause of obesity. In addition, a lack of exercise and physical activity are also contributors to obesity. Diabetes is a comorbidity of obesity.[1] If you want to reduce your chances of developing diabetes, you need to maintain a normal weight.

Definition of Obesity

Obesity is a specific physical condition. This disorder features an excessive amount of energy (calorie) storage in the body mainly in the form of fat[2]. Defined in terms of body mass index referred to as BMI, an overweight person is anyone who has a BMI of 25 or more while an obese person is anyone who measures over 30 on the BMI scale. BMI uses weight and height and a formula to create a measure compared to standards to determine if a person is underweight, at a normal weight, overweight or excessively overweight which is called obese.

BMI is used as a measure because it correlates to body fat.

Another way to define obesity is a person weighs more than 20 percent of normal weight for their height.

Body fat Should Be in Proportion

Body fat is divided into two groups:

  • Essential body fat – Essential fat is necessary to life and the reproduction of the species. For example, some fat is needed to cushion organs. As a proportion of total body fat, it makes up to 5% in men and 12% in women. Your body has a specific requirement level for essential fat. If the levels fall too low, it can affect your health.
  • Storage body fat – This is the excess amount of fat stored in your body. It is required for energy, but sometimes the amounts available in storage exceed the body’s needs. As a result it remains stored and can have detrimental effects on your health.

The National Institute of Health provides wide parameters of acceptable body fat composition. In men the number is between 6% and 24 %; in women, the amount is 14% to 31%.

Body Mass Index (BMI)

Body Mass Index calculations give you an easy way to determine how your weight compares to normal weight. Using weight and height this measurement is considered to have its advantages and disadvantages. Some see it as a beneficial tool for population studies, but not appropriate for assessing the individual. Other problems related to the use of BMI include:

  • It cannot tell the difference between muscles and fat
  • It is incapable of distinguishing that atrophy of any muscles has occurred resulting in its replacement with fat
  • It fails to tell you anything concerning the allocation of fat in your body
  • The scale fails to compensate adequately for height. This inaccuracy may be compensated for by using one of two scales: Ponderal suggested a scale of kgm/m3 and Korevaar suggested a scale somewhere in between

Using this form of measurement the government has established specific standards. Essentially, the following figures indicate the variety of possibilities or classifications[3]:

  • 20-25 BMI is optimal
  • Less than 20 is underweight
  • Over 25 is considered overweight
  • Over 30 is obese
  • Over 40 is “morbidly” obese

Within the classifications of obesity, there are further subdivisions. These are: Class 1 from BMI 30 to 35; Class 2 from 35 to 40and Class 3 over 40. Classes 2 and 3, the “over 35” group, has been further subdivided. A BMI in the 35 to 50 range is called “morbid obesity.” If your BMI is over 50, it is referred to as “super obesity.”

The practical application of these distinctions lies in the medical decision of whether to treat the obesity or not. When such serious interventions as surgery are contemplated, the general consensus is that it should apply to those most affected which is the people who have a BMI at the top of the Class 3 obesity grouping. As such the BMI may prove to be a useful tool. It remains a constant in government measurements as to where an individual fits in terms of weight.  In 2007, a population survey indicated that 63% of all Americans are overweight. Moreover, 26% of all Americans are obese.

Body Volume Index (BVI)

When it comes to obesity, not all fat is created equal. In addition, it does matter where the excess fat resides on the body. Body shape matters. The BVI is a useful tool in this respect. It helps to differentiate persons with central obesity from other. Central obesity is considered to be the most harmful to health, increasing the risk of cardiovascular disease.

How Does this Help?

Knowing whether you are clinically obese is beneficial in several ways. It helps clarify to your physician and you the state of your physical being. Knowing you are a normal weight, overweight or obese can act as a motivator to make dietary changes or to lose weight. It can help you address the underlying causes of any weight-related issues.[4]

In doing so, it may aid in your goal to get your diabetes under control or even prevent you as a prediabetic from becoming diabetic. Remember, as one researcher states: “Obesity is a sign – overeating is a symptom.”[5]

People who are obese have a higher risk of developing type 2 diabetes. Being overweight stresses the biological systems and that includes the ability to maintain correct blood glucose levels. Too much fat in the bloodstream and body can lead to insulin resistance.

When you learn that approximately one-third of all adults are classified as obese, it’s easy to understand why diabetes rates are increasing so rapidly.


Defining obesity can be strictly clinical. It can be a simple measurement involving the BMI and/or the BVI. Yet, the actual causes of obesity are complex and relate specifically to each individual. You will need to address what is at the root of your problem before you can get a handle on other issues related to obesity. If you want to reach your goal of control over your diabetes, you may have to look at various aspects of your life and lifestyle. These include utilizing behavioral changes and even looking at the possibility that your inability to control your weight and, therefore, your diabetes may be the result of more complex issues such as emotional eating or an addiction to eating.[6]


[1] Singh, AK; Singh, SK; Singh, N; Agrawal, N; and Goal, K (2011). “Obesity and Dyslipidemia.”  Int J Biol Med Research, 2(3): 824-82.

[2] Marcovitch, H (2006). Black’s Medical Dictionary 41st edition. Lantham, Maryland: Scarecrow Press.

[3] CDC (2011). Assessing Your Weight.” Retrieved from

[4] Webber, KH; Tate, DF: Ward, DS; and Bowling, M (2010). “Motivation and its Relationship to Adherence to Self-monitoring and Weight-loss Intervention.” Journal of Nutrition Education and Behavior. 42(3): 161-167.

[5] Sharma, AM; and Padwal, R (2010). “Obesity is a Sign – Over-Eating is a Symptom: An Aetiological Framework for the Assessment and Management of Obesity.” Obesity Reviews, 11(5): 362–370.

[6] Taylor, VH; Curtis, CM; and Davis, C (2010). “The Obesity Epidemic: The Role of Addiction.” CMAJ, 182 (4): 327-328.

[7] This article was originally published July 12, 2012 and last revision and update of it was 9/10/2015.