9.1 – Too Little or Too Much Weight?

Learning Objective

  • Discern the differences in health risks associated with being underweight and being overweight.
  • Describe factors that encourage excess body fat storage and obesity.


The number of people considered overweight and obese in the world has now surpassed the number of people starving, with some officials estimating that the number of overweight people is nearly double the number of underweight people worldwide. Countries that have more recently modernized, industrialized, and urbanized are experiencing a surge in their overweight and obese populations. China, the most populous country in the world, now has more than 1.3 billion people. 10.8% of men and 14.9% of women are overweight. The rate of increase in obesity in children is even more striking. “For instance, in rural Shandong province, the rate of obese and overweight boys jumped from 0.5% in 1985 to 30.7% in 2014; in girls, the percentage increased from 0.8% to 20.6% over the same period.” 1 The increase in China’s waistline is partly attributed to changes in the traditional diet, more sedentary lives, and a massive increase in motor vehicle use. Moreover, China’s recent famines in the 1950s, which affected the poor and lower classes to a greater extent than the upper class, has sanctioned lax social attitudes toward body fat and reinspired the age-old Chinese belief that excess body fat represents health and prosperity.

The associated diseases of overweight and obesity happen over many years and signs and symptoms commonly take decades to manifest. With China’s younger population and other developed countries experiencing a dramatic weight increase, the associated chronic diseases will come about much earlier in life than in previous generations. This will put an even greater burden on society.

1 Sun C. Obesity: A growing problem in China. Obes Res Open J. 2018; 5(1): e1-e2. DOI: 10.17140/OROJ-5-e013


Video: 9.1.1 – Chinese Obesity

This video discusses the surge in Chinese obesity and how the country’s rapid increase in modernization contributes to its obesity epidemic.

Author: cjnr
Published on Sep 28, 2006


Health Risks of Being Overweight and Being Obese


State Map of the Prevalence of Obesity in America

Visit this web page to see the obesity trends in 2017. As you will see, the percentages of obese adults are rising.


As B.M.I.s increase over 25, the risks increase for heart disease, Type 2 diabetes, hypertension, endometrial cancer, postmenopausal breast cancer, colon cancer, stroke, osteoarthritis, liver disease, gallbladder disorders, and hormonal disorders. The W.H.O. reports that obesity has nearly tripled since 1975. 2

Similar to other public health organizations, the W.H.O. states the main causes of the obesity epidemic worldwide are the increased intake of energy-dense food and decreased levels of physical activity that are mainly associated with modernization, industrialization, and urbanization. The environmental changes that contribute to the dietary and physical activity patterns of the world today are associated with the lack of policies that address the obesity epidemic in the health, urban planning, agriculture, food industry, and education sectors.

2 World Health Organization. “Obesity and Overweight.” Accessed May 16, 2019. 



Health Risks of Being Underweight

The 2015-2016 National Health and Nutrition Examination Survey (NHANES) estimated that 1.5 percent of adults aged 20 and older are underweight. Centers for Disease Control and Prevention. Prevalence of Underweight Among Adults Aged 20 and Over: United States, 1960–1962 Through 2015–2016 Accessed May 16, 2019. Being underweight is linked to nutritional deficiencies, especially iron-deficiency anemia, and to other problems such as delayed wound healing, hormonal abnormalities, increased susceptibility to infection, and increased risk of some chronic diseases such as osteoporosis. In children, being underweight can stunt growth. The most common underlying cause of underweight in America is inadequate nutrition. Other causes are wasting diseases, such as cancer, multiple sclerosis, tuberculosis, and eating disorders. People with wasting diseases are encouraged to seek nutritional counseling, as a healthy diet greatly affects survival and improves responses to disease treatments. Eating disorders that result in underweight affect about 0.8% of adults in the U.S. 3

Malnutrition exists in different forms around the world. Explore more about malnutrition through the W.H.O. website.

3 Udo, T. et al. Prevalence and Correlates of DSM-5–Defined Eating Disorders in a Nationally Representative Sample of U.S. Adults. 2018; 84 (5),345 – 354. Accessed June 30, 2019. 


Eating Disorders

Cynthia Bulik, Ph.D., an NIMH grantee at the University of North Carolina, debunked nine myths about eating disorders at the NIMH Alliance for Research Progress Winter Meeting, February 7, 2014, in Rockville, MD. Among her key messages:

  • Eating Disorders do not discriminate, they affect males and females, young and old.
  • You can’t tell by someone’s size whether they have an eating disorder.
  • Families do not cause eating disorders – they can be patients’ best allies in treatment.
  • Both genetic and environmental factors influence eating disorders.
  • Eating disorders are serious biologically-influenced mental illnesses, not passing fads.
  • Complete recovery is possible.4

Watch “The Nine Truths About Eating Disorders” from the cast of “To the Bone” based on the lecture given by Cynthia Bulik here.

Visit the World Eating Disorders Day webpage for more information regarding eating disorders: https://www.worldeatingdisordersday.org/about/nine-truths/


4 9 Eating Disorders Myths Busted February 27, 2014 • Science Update NIMH;  Accessed May 16, 2019.



Anorexia Nervosa

Anorexia nervosa, more often referred to as “anorexia,” is a psychiatric illness in which a person severely restricts their food intake, sees themselves as weighing more than they actually do, and may use purging strategies such as vomiting or exercise to limit weight further. 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, The National Institute of Mental 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 kilocalories per day and may 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 diets or starves him- or herself may trigger the onset of anorexia. It is a genetic disease and it may be passed from one generation to the next. Pregnancy complications and abnormalities in the brain, endocrine system, and immune system may all contribute to the development of this illness.

The primary signs of anorexia are fear of being overweight, fear of consuming food or changes in eating patterns, an unusual perception of body image, and depression. The secondary signs and symptoms of anorexia are all related to the caloric and nutrient deficiencies of the unbalanced diet and include excessive weight loss, a multitude of skin abnormalities, diarrhea, cavities and tooth loss, osteoporosis, and 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 not only the individual, but also family, friends, and a psychiatric counselor. Treating anorexia also involves a Registered Dietitian Nutritionist, who helps to 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. Many people do recover from anorexia. The sooner an individual begins treatment, the more likely they can make a full recovery.



Bulimia, like anorexia, is a psychiatric illness that can have severe health consequences. In a study published in 2011 of a nationally representative sample of US adolescents, the lifetime prevalence of BN of 1.3 % and 0.5 % was found among 13–18-year-old females and males, respectively.1 Bulimia is characterized by episodes of eating large amounts of food followed by purging, which is accomplished by vomiting or with the use of 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 bouts of excessive exercise. 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. 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

Similar to those who experience anorexia and bulimia, people who have a binge-eating disorder have lost control over their eating.  People with a binge-eating disorder will periodically overeat to the extreme, but their loss of control over the quantity they eat is not followed by fasting, purging, or compulsive exercise. As a result, people with this disorder are often overweight or obese, and their chronic disease risks are those 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. Lifetime prevalence estimates are 2.3% for females and 0.8% for males.5 Treatment often involves antidepressant medication as well as nutritional and psychiatric counseling.

5 Swanson SA, Crow SJ, Le Grange D, Swendsen J, Merikangas KR. Prevalence and correlates of eating disorders in adolescents. Results from the national comorbidity survey replication adolescent supplement. Arch Gen Psychiatry. 2011;68(7):714–723. DOI:10.1001/archgenpsychiatry.2011.22. Accessed June 30, 2019. 


Key Takeaways

  • The number of people considered overweight and obese in the world has now surpassed the number that is starving. As B.M.I.s increase over 25, the risks increase for heart disease, Type 2 diabetes, hypertension, endometrial cancer, breast cancer, colon cancer, stroke, osteoarthritis, liver disease, gallbladder disorders, and hormonal disorders.
  • Being underweight is linked to nutritional deficiencies. These deficiencies cause iron-deficiency anemia and also delayed wound healing, hormonal abnormalities, increased susceptibility to infection, and increased risk of some chronic diseases such as osteoporosis. In children, being underweight can stunt growth.
  • Eating disorders resulting in being underweight can have severe consequences to health. The eating disorder anorexia nervosa has the highest mortality rate of all mental illnesses. All underweight people do not have anorexia and all overweight people do not have an eating disorder.


Discussion Starters

  1. Visit the Food and Agriculture Organization of the United Nations website and discuss the impact of the rise in obesity in developing countries.
  2. Many individuals have implicit and explicit weight bias. Even as adults in this society we “profile” people with excess body fat  with disrespectful adjectives.  Moreover, society commonly “profiles” people who are too skinny as well. Propose ideas for improving body image during the teenage years.


Icon for the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

Nutrition 100 Nutritional Applications for a Healthy Lifestyle Copyright © by Lynn Klees and Alison Borkowska is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

Share This Book