3 Energy Needs, Obesity, and Disordered Eating


  • Your Energy Needs
  • Body Mass Index (BMI)
  • Obesity Trends
  • Disordered Eating

Nutrition and Your Body

Physical appearances can be deceiving when it comes to your health status. Just because someone is muscular and fit does not mean that their cholesterol and blood pressure is in a healthy range. In this chapter, we will examine the Body Mass Index, body shape, and obesity trends. Next, we will examine how we judge our appearance and disordered eating.

How can we tell if the Body is Healthy?

One way to tell if a body is healthy is to determine the body’s composition (how much muscle and fat).  There are numerous ways to measure body composition, but the one you may have heard about at both the doctor’s office and the news is BMI, which stands for body mass index.  BMI is calculated using height and weight and is an inexpensive and easy screening method to indicate your weight category.

BMI Weight Category
Below 18.5 Underweight
18.5-24.9 Healthy weight
Over 25-29.9 Overweight
Over 30 Obese

Having a high BMI is associated with an increased risk for many diseases and health conditions, such as heart disease, Type 2 diabetes, hypertension, endometrial cancer, breast cancer, colon cancer, stroke, osteoarthritis, and liver disease, gallbladder disorders, and hormonal disorders.  BMI is not a perfect measure; other calculations are needed to diagnose obesity and disease risk.  One example of a drawback of BMI is that it may incorrectly categorize someone who is very muscular, such as a football player or bodybuilder; however, this is a less common scenario. You will learn what your BMI is later in this chapter.

Body Fat Caliper

Another way to evaluate the composition of the body is to measure fat and assess fat distribution.  The easiest way to measure fat is with a skinfold test using a caliper.  A health professional with a caliper (a large tool that looks kind of like pinchers) will measure your skin’s thickness on the back of your arm, back, and several other areas of the body.  This test is inexpensive, non-invasive, and fairly accurate.

The distribution of fat on the body is just as important as the body’s amount of fat.  An easy way to measure distribution is by calculating the waist-to-hip ratio.  If you have a greater difference between your waist and hip measurements, you are considered pear-shaped.  If you have little difference between your waist and hips, you have a classic apple shape, which has a greater risk for chronic disease.  Where you carry your weight affects your health.




Watch this video to learn how to calculate your waist-to-hip ratio

Balancing Energy Input and Energy Output

The USA has been suffering an obesity epidemic for more than thirty years.  The number of people considered overweight and obese has now surpassed the number that is starving.  There are many reasons for this enormous rise in obesity, but a primary cause is that people are eating too much and moving too little.

The Obesity Trend Across the United States 1985-2010


Basal Metabolic Rate

Your basal metabolic rate (BMR) is the number of calories you burn while your body is at rest. Yes. That’s right; you burn the largest percentage of calories –about two-thirds while you are sleeping or sitting.  These calories are used for running your body processes such as your brain, breathing, body growth, and repair. Another thing to take into consideration is how much lean muscle mass to body fat you have. Muscle tissue is metabolically active, meaning you burn more calories over the course of a day. Men typically have a larger percentage of lean muscle mass than women and therefore tend to have a higher BMR. Fat is not metabolically active. If you are eating more food than you need for energy, your body will convert those excess calories into fat. Additionally, people who are taller or pregnant will also burn more calories.

While you can figure out how much energy you are taking in by counting your calories, it’s a bit harder to know how much energy you are using because you burn calories through three different activities:

  • While at rest /BMR
  • Doing physical exercise
  • Digesting food

Take a look at how active you are based on the three categories below.  Which category best describes your activity level?



A lifestyle that includes only the physical activity of independent living.

Moderately Active


A lifestyle that includes physical activity equivalent to walking about 1.5 to 3 miles per day at 3 to 4 miles per hour, in addition to the activities of independent living.



A lifestyle that includes physical activity equivalent to walking more than 3 miles per day at 3 to 4 miles per hour, in addition to the activities of independent living.

*Estimates for females do not include women who are pregnant or breastfeeding.

Complete the activity in the blue text box below to determine your individual nutrient needs.

What is Your Daily Nutrient Recommendations (DRI)?

Use the link below to the DRI calculator to learn your:

  • Estimated daily calorie needs
  • Macronutrient needs (carbohydrates, protein, and fat)
  • Micronutrients (vitamins & minerals)
  • BMI


If you want to increase the energy you burn, the best way to do so is by increasing your physical activity.  But energy intake and expenditure are regulated by very complex systems in the body and are affected by genetics, behavior, and society.  The equation is not simply energy in = energy out.  Dieting is practically an American pastime, but it isn’t a solution for poor eating habits or lack of exercise.  There are health risks associated with BOTH being overweight and underweight.  But there is a healthy weight to aim for; talk to your physician and a registered dietitian about how to improve your diet and exercise regime to optimize your health.

Disordered Eating

A person with disordered eating has attitudes and behaviors towards his or her body that range from being unhappy with their body shape to unhealthy eating, dieting, and exercise habits. A person must be diagnosed by a physician or psychologist using the Diagnostic and Statistical Manual, Fifth Edition (DSM-V) criteria. This manual lists the symptoms associated with each type of disorder.

Disordered Eating

Eating disorders can have severe consequences for health. Here are five eating disorders listed below. Click on each type to learn more.

Guess Her Weight

Watch the video and see if you can guess the correct weight for these women.

Anorexia Nervosa

Anorexia nervosa, more often referred to as “anorexia,” is a psychiatric illness in which a person obsesses about their weight and about food that they eat. Anorexia results in extreme nutrient inadequacy and eventually to organ malfunction. Anorexia is relatively rare—the National Institute of Mental Health (NIMH) reports that 0.9 percent of females and 0.3 percent of males will have anorexia at some point in their lifetime. Still, it is an extreme example of how an unbalanced diet can affect health.

Anorexia frequently manifests during adolescence, and it has the highest rate of mortality of all mental illnesses. People with anorexia consume, on average, fewer than 1,000 kilocalories per day and exercise excessively. They are in a tremendous caloric imbalance. Moreover, some may participate in binge eating, self-induced vomiting, and purging with laxatives or enemas. The very first time a person starves him- or herself may trigger the onset of anorexia. The exact causes of anorexia are not completely known, but many things contribute to its development, including economic status, which is most prevalent in high-income families. It is a genetic disease and is often passed from one generation to the next. Pregnancy complications and abnormalities in the brain, endocrine system, and immune system may contribute to the development of this illness.

The primary signs of anorexia are fear of being overweight, extreme dieting, an unusual perception of body image, and depression. The secondary signs and symptoms of anorexia are related to the caloric and nutrient deficiencies of the unbalanced diet. They include excessive weight loss, a multitude of skin abnormalities, diarrhea, cavities and tooth loss, osteoporosis, liver, kidney, and heart failure. There is no physical test that can be used to diagnose anorexia and distinguish it from other mental illnesses. Therefore a correct diagnosis involves eliminating other mental illnesses, hormonal imbalances, and nervous system abnormalities. Eliminating these other possibilities involves numerous blood tests, urine tests, and x-rays. Coexisting organ malfunction is also examined. Treatment of any mental illness involves the individual and family, friends, and a psychiatric counselor. Treating anorexia also involves a dietitian who helps provide dietary solutions that often have to be adjusted over time. The goals of treatment for anorexia are to restore healthy body weight and significantly reduce the behaviors associated with causing the eating disorder. Relapse to an unbalanced diet is high. Many people recover from anorexia; however, most continue to have lower-than-normal body weight for the rest of their lives.


Bulimia, like anorexia, is a psychiatric illness that can have severe health consequences. The NIMH reports that 0.5 percent of females and 0.1 percent of males will have bulimia at some point in their lifetime.

Bulimia is characterized by episodes of eating large amounts of food followed by purging, which is accomplished by vomiting, laxatives, and diuretics. Unlike people with anorexia, those with bulimia often have a normal weight, making the disorder more difficult to detect and diagnose. The disorder is characterized by signs similar to anorexia, such as fear of being overweight, extreme dieting, and excessive exercise bouts. Secondary signs and symptoms include gastric reflux, severe erosion of tooth enamel, dehydration, electrolyte imbalances, lacerations in the mouth from vomiting, and peptic ulcers. Repeated damage to the esophagus puts people with bulimia at an increased risk for esophageal cancer. The disorder is also highly genetic, linked to depression and anxiety disorders, and most commonly occurs in adolescent girls and young women. Treatment often involves antidepressant medications and, like anorexia, has better results when both the family and the individual with the disorder participate in nutritional and psychiatric counseling.

Binge-Eating Disorder

Like those who experience anorexia and bulimia, people who have a binge-eating disorder have lost control of their eating. Binge-eating disorder is not currently diagnosed as a distinct psychiatric illness, although there is a proposal from the American Psychiatric Association to categorize it more specifically. People with binge-eating disorder will periodically overeat to the extreme, but their loss of control over eating is not followed by fasting, purging, or compulsive exercise. As a result, people with this disorder are often overweight or obese. Their chronic disease risks are linked to having an abnormally high body weight, such as hypertension, cardiovascular disease, and Type 2 diabetes. Additionally, they often experience guilt, shame, and depression. Binge-eating disorder is commonly associated with depression and anxiety disorders. According to the NIMH, binge-eating disorder is more prevalent than anorexia and bulimia and affects 3.5 percent of females and 2.0 percent of males at some point during their lifetime. Treatment often involves antidepressant medication as well as nutritional and psychiatric counseling.

Orthorexia Nervosa

It is an obsession with healthful eating. It was recognized in 1998, although it is not listed in the Diagnostic and Statistical Manual and the top three eating disorders previously discussed. Unfortunately, this makes it difficult to estimate how many people suffer from this eating disorder. Orthorexia involves the following symptoms:

  • A compulsion to check ingredient lists and labels
  • Increased concern and stress about the health of ingredients
  • Spending a large percentage of time obsessing about your food and what other people eat
  • Eating a small variety of foods due to the elimination of various food groups.


Pica is a psychological disorder in which the person compulsively eats items with no nutritional value, such as dirt, chalk, laundry detergent, or hair. The diagnosis is made from a clinical history of the patient.

Watch the video to learn more about PICA (4 minutes)


Learning Objectives

  • Define and discuss common measurements to assess body composition and health risk. (MCCCD Competency 1)
  • Utilize the DRI tool to determine your BMI and nutrient needs. (MCCCD Competency 2)
  • Describe what energy balance is and how it affects weight status. (MCCCD Competency 9)
  • Compare and contrast body types with health status. (MCCCD Competency 8)
  • Name the five common eating disorders and briefly describe them. (MCCCD Competency 9)




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Nutrition Essentials Copyright © 2020 by Stephanie Green and Kelli Shallal is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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