Nutrition and Obesity

last authored: Nov 2014, Christy Charles
last reviewed: Nov 2014, Kathy Foster; Rebecca Green-LaPierre



main article: obesity

Obesity occurs when there is an imbalance between the amount of food consumed and energy expended, with more energy being consumed than expended. Factors including lifestyle, genetics, and environment may all contribute to an individual’s weight. Obesity is an issue of concern as there is a positive relationship between obesity and many chronic diseases such as type 2 diabetes, cardiovascular disease, stroke, hypertension, sleep apnea, and hormonal cancers.  


Obesity is a health issue worldwide: the World Health Organization estimates that worldwide obesity has nearly doubled since 1980 and that as of 2008, more than 1.4 billion adults, age 20 years and older, were overweight - of these over 200 million men and nearly 300 million women were obese (WHO, 2014).   In Canada, 62% of men and 42% of women aged 18 years and older were overweight or obese (Statistics Canada, 2014).  In South Sudan, 40.4% of men and 48.5% of women aged 20 years and older were overweight or obese (Ng et al, 2014).


In this paper we will discuss the energy imbalance that leads to obesity, classification of overweight and obesity, and the assessment and treatment of individuals who are obese.

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Energy Balance

There are many components of energy consumption and expenditure to consider. in the energy balance equation.  The following list includes factors affecting energy consumption:

Total food and alcohol intake

The following list includes factors affecting energy expenditure:

Because many factors of the energy balance equation correlate with the amount and type of foods consumed, it is necessary to understand how primary care providers can estimate their patients’ dietary needs.


Dietary Reference Intakes (DRIs) provide the foundation for building a healthy diet by detailing human nutritional requirements (Health Canada, 2010).  They are a set of values that serve as standards for nutrient intakes for healthy persons in Canada and the United States. Thus, with relative confidence, we can estimate caloric, macronutrient, and (most) micronutrient needs an individual will need to consume each day to meet their nutritional and health needs, depending on their gender and age.





Estimated Energy Requirements

Estimated Energy Requirement (EER) is defined as the dietary energy intake that is predicted to maintain energy balance in a healthy adult of a defined age, gender, weight, height, and level of physical activity, consistent with good health (Health Canada, 2010).


Adults 19 years and older:
Estimated Energy Requirement (kcal/day) = Total Energy Expenditure
Men EER = 662 - (9.53 x age [y]) + PA x { (15.91 x weight [kg]) + (539.6 x height [m]) }
Women EER = 354 - (6.91 x age [y]) + PA x { (9.36 x weight [kg]) + (726 x height [m]) }


Physical Activity Coefficients (PA values) for use in EER Equations (Health Canada, 2010):



Sedentary (PAL 1.00 - 1.39)
Typical daily living activities (e.g. household tasks, walking to the bus)

Low Active (PAL 1.40-1.59)
Typical daily living activities PLUS 30-60min of daily moderate activity (e.g. walking at 5-7km/hour)

Active (PAL 1.60-1.89)
Typical daily living activities PLUS at least 60min of daily moderate activity

Very Active (PAS 1.90-2.50)
Typical daily activities pLUS at least 60min of daily moderate activity PLUS an additional 60min of vigorous activities or 120min of moderate activity

Boys 3-18y





Girls 3-18y





Men 19y+





Women 19y+







Acceptable Macronutrient Distribution Ranges

Acceptable Macronutrient Distribution Ranges (AMDR) are the range of intakes of an energy source that is associated with a reduced risk of chronic disease yet can provide adequate amounts of essential nutrients.
The Macronutrients that provide energy are carbohydrates, lipids (fat) and protein.  A typical healthy adult should receive:

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Classification of Overweight and Obese


Body Mass Index

In the absence of hormonal problems such as hypothyroidism or Cushings disease, typically people are overweight because they consume too many calories and do not expend enough energy to compensate for their dietary intake. The most commonly used classification system of overweightness and obesity uses body mass index (BMI) as cut off points (WHO, 2006).  The formula to calculate BMI = weight(kg)/height (meters2)



Body Mass Index


< 18.5


18.5 - 24.9


25.0 - 29.9

Obesity, Class 1

30.0 - 34.9

Obesity, Class 2

35.0 - 39.9

Obesity, Class 3

> 40.0



Waist Circumference and Waist/Hip Ratio

Another measure of obesity is waist circumference. There are a few different guidelines in terms of waist circumference and risk of metabolic complication. The World Health Organization guidelines are that a waist circumference of >102cm (40 inches) for men and >88cm (35 inches) for women indicate an increased risk (WHO, 2011). Risk of metabolic complication and waist circumference cut offs vary by ethnicity, with Asians having a lower cut off point than Europids.


A third helpful measure of obesity is waist/hip ratio. A ratio of more than 0.85 for women and 0.9 for men is indicative of an elevated risk for cardiovascular events such as heart attack and stroke.


World Health Organization cut-off points and risk or metabolic complications (WHO, 2011)



Cut-Off Points, MEN

Cut-Off Points, WOMEN

Risk of Metabolic Complications

Waist Circumference, Europids

>94 cm

>80 cm


Waist Circumference, South Asians, Chinese and Japanese*

>90 cm

>80 cm


Waist Circumference

> 102 cm

>88 cm

Substantially Increased

Waist to Hip Ratio

>/= 0.90cm

>/= 0.85cm

Substantially Increased

* International Diabetes Federation cut-off points for different ethnic groups

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Nutrition Assessment  

A thorough assessment, exploring the patients’ typical food intake, level of physical activity and other lifestyle factors will help identify areas that are contributing to an unbalanced energy equation, and then the primary care provider and patient together can set realistic goals to help the patient consume less and expend more.

  • History
  • Physical Exam
  • Lab Investigations


  • Assess for co-morbidities  (e.g. diabetes, dyslipidemia, hypertension) as each requires unique nutrition therapy that will augment the diet therapy for overweight and obesity alone.
  • Know all medications the patient is on, specifically assess for hypertension treatments that will affect Na or K blood levels.
  • Inquire about symptoms of heartburn which is common in the overweight patient.
  • Take a comprehensive dietary history
    • Use a 24hr recall or 3-day food record as well as a food frequency questionnaire to assess what your patient is eating. A nutrient software analysis program is ideal to assess actual intake; however, a detailed multi-day food record can also show insufficient and/or excessive intake of nutrients.
    • Identify items consumed often that are high in fat,and/or sugar as they may be contributing to caloric excess.
    • Discuss how foods are prepared and identify any higher fat cooking methods (frying, deep frying) or areas where excess fats are added (during preparation, cooking, or at meal time).
    • Ask about beverages- is the patient drinking sugar sweetened beverages (regular pop or fruit juice/drink), alcohol, or beverages with cream (coffee or tea).
    • Meal pattern- how often does the client eat throughout the day? Are they skipping meals? Do they mindlessly snack throughout the day?
  • Additional to what the patient actually eats, discuss environmental influences
    • Where does the patient purchase their food? How often do they get groceries (daily, weekly, monthly)?
    • What is the socioeconomic status of the patient? Are they able to afford the food they need and want?
    • Is the cost of fresh/healthy food prohibitive for the patient?
    • Does the patient cook for themselves or does someone else cook for them? Do they have cooking skills.
    • Is the patient physically active? How often and at what intensity?  Do they have any medical conditions that prevent them from participating in physical activity?
    • Access to health care, medications, and vitamins/mineral supplements?

Physical Exam

  • Collect the patient’s height and weight to calculate BMI.  Collect WC and WHR. Identify classification of overweightness.
  • Inquire about how clothes fit, changes in clothing sizes.
  • Inquire about patterns of weight gain - was the gain sudden or gradual?  Did it start after the initiation of a medication or a traumatic life experience?  Can you attempt to identify the reason/impetus for the weight gain?
  • Ongoing monitoring of blood pressure.

Laboratory Investigations

Assess blood glucose and/or Hemoglobin A1C to determine risk of type 2 diabetes.

Analyze lipid panel to determine presence of dyslipidemia.

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Nutrition Management for Obesity

There are a variety of techniques available to aid in long term weight loss and further weight management. Effective weight loss regimens include modification of food choices, physical activity, behaviour modification, education on nutritional principles, and mental health support/coaching. Lifestyle modification is the first plan of action when attempting to lose weight- pharmacotherapy and bariatric surgery should be considered secondary plans of action.


Modest weight loss of as little as 5-10% can be beneficial in reducing the comorbidities associated with obesity. For example, even a 10-20 pound weight loss for an individual weighing 200 pounds, could show positive improvements in blood pressure and serum cholesterol levels.


Strict low calorie diets have not been proven to be effective over the long term as they are very hard to maintain and as soon as a client ‘goes off’ the diet they are likely to gain the weight back, and often over time will gain back more than they lost in the first place.

For a healthier lifestyle:

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Resources and References

Dietitians of Canada

Center for Disease Control and Prevention

World Health Organization

American Heart Organization Obesity Guidelines 2013


Escott-Stump, S.,(2012). Nutrition and Diagnosis- Related Care (7th ed.) Baltimore, MD.: Lippincott Williams & Wilkins.

Health Canada (2010). Dietary Reference Intake Tables. Retrieved from: Accessed Oct 30, 2014.

Mahan, L. K., Escott-Stump, S., Raymond, J. L., & Krause, M. V. (2012). Krause's food & the nutrition care process (13th ed.). St. Louis, MO.: Elsevier/Saunders.

Ng et. al (2014). Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013; a systematic analysis for the global burden of disease study 2013. Lancet 384 (766-781).

Statistics Canada (2014). Body mass index, overweight or obese, self-reported, adult, by sex, provinces and territories. Retrieved from: Accessed Nov 23, 2014

World Health Organization. (2006). BMI classification. Retrieved from:  Accessed November 12, 2014,

World Health Organization (2011). Waist circumference and waist–hip ratio: report of a WHO expert consultation, Geneva, 8–11.

World Health Organization (2014). Obesity and Overweight Fact Sheet. Retrieved From: Accessed Nov 23, 2014



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