What is Obesity?
What is Obesity?
Obesity is a multi-faceted and highly complex medical condition. There is no shortage of information on the topic, but how does one separate fact from fiction? In this section, gain a basic understanding of obesity and learn some key terminology.
Obesity Explained1
- The terms "overweight" and "obese" describe weight ranges that are above what is medically accepted as healthy
- Being in either the overweight or obese weight ranges increases the likelihood of certain diseases and health problems
- Over one-third of U.S. adults (~36%) are obese
- Approximately 12.5 million children and adolescents aged 2-19 (17%) are obese
- Obesity affects people of all ethnic backgrounds, income and education levels. The highest overall obesity rates continue to be found amongst racial and ethnic minorities, those with lower levels of education and lower income levels, and in rural populations
As an Adult, How Do I Know If I Am Overweight or Obese?
- Weight and height are used to calculate a number called the "body mass index" (BMI). For most people, BMI is a good estimate of body fatness.
- A BMI of 25 to 29.9 is considered overweight.
- A BMI of 30 or higher is considered obese.
- To find your BMI, try one of these BMI calculators:
For example, if your height is 5' 9" and you weigh between 169-202 lbs., you are considered overweight; if you weigh over 202 pounds, you are considered obese.
How Do I Know If My Child or Teen is Overweight or Obese?
- BMI for children and teens is calculated the same way as for adults, but is interpreted differently because body fat:
- changes with age
- is different between girls and boys
- Use the age and gender specific BMI calculator for children and teens. Once calculated, the number can be looked at on a CDC BMI-for-age gender-specific growth chart. Or you can use this calculator.
- Percentiles are the most commonly used way to evaluate the size and growth patterns of individual children in the United States. A BMI percentile shows how your child's BMI compares to that of other kids their age and sex in a healthy population.
Weight status categories and corresponding percentiles are shown in the following table.
What Are the Health Consequences of Being Overweight or Obese?
- The link between BMI and health risks is well established. Overweight and obese individuals are at increased risk for many diseases and health conditions:
- High blood pressure (HBP) or hypertension refers to increased pressure as blood flows through the arteries. Elevated blood pressure forces the heart to work harder than normal to circulate blood throughout the body.
- High blood cholesterol or dyslipidemia (abnormal levels of fat in the blood) occurs when levels of cholesterol (a type of fat that your body needs to work properly) and other fats in the blood are not normal. There are different types of fats in the blood, including LDL cholesterol ("bad" cholesterol), HDL cholesterol ("good" cholesterol), and triglycerides. Too much LDL and triglycerides, and too little HDL increases your risk for developing heart disease, stroke, and other circulatory problems.
- Type 2 diabetes is a disease in which the body does not produce enough insulin and/or the body's cells have trouble using the insulin it does produce. Insulin is necessary for sugar (glucose) to be taken up by body cells for energy production. Without insulin, blood sugar levels build up in the blood. If untreated, serious complications result.
- Coronary heart disease or coronary artery disease (CHD or CAD): CHD or CAD is the leading cause of death in the United States for men and women. It is a narrowing of the small blood vessels that supply blood and oxygen to the heart.
- Stroke occurs when the flow of oxygen-rich blood to a portion of the brain is blocked. Without oxygen, brain cells start to die after a few minutes. There are two major types of stroke: ischemic stroke and hemorrhagic stroke. Ischemic stroke occurs when a blood vessel that supplies blood to the brain is blocked by a blood clot. These may be caused by clogged arteries from accumulation of fat, cholesterol, and other substances that collect on the artery walls, or from other causes like a blood clot traveling from elsewhere in the body to the brain. A hemorrhagic stroke happens when a blood vessel in part of the brain becomes weak and bursts open, causing blood to leak into the brain.
- Gallbladder disease occurs when bile, which is normally stored in the gall bladder and helps digest dietary fat, becomes concentrated and thick. Gallstones are formed when bile hardens.
- Osteoarthritis is a gradual deterioration of the joint tissue due to excessive wear and tear.
- Sleep apnea is a condition in which breathing repeatedly stops and starts, or shallow breaths occur, during sleep because of partial or total blockage of the airway.
- Cancer, including cancer of the esophagus, breast, endometrium, colon and rectum, kidneys, pancreas, thyroid, gallbladder, and possibly others are associated with overweight and obesity.
- Nonalcoholic Fatty Liver Disease (NAFLD) and Nonalcoholic Steatohepatitis (NASH) NAFLD is a condition in which fat builds up in the liver. In NASH, fat in the liver is accompanied by inflammation and fibrosis, or scarring, of the liver. NASH is an advanced form of NAFLD. NAFLD and NASH affect the liver in the same way that alcoholic liver disease does, but NAFLD and NASH occur in people who drink little or no alcohol.
- Quality of life is an indicator of general well-being that incorporates physical and mental factors.
- Childhood obesity is associated with:
- a higher chance of obesity, disability and premature death in adulthood.
- breathing difficulties, increased risk of fractures, hypertension, and risk factors for cardiovascular disease, insulin resistance and psychological effects.
Causes of the Obesity Epidemic: Understanding Energy Balance2,157
- Many factors play a role in the development of obesity, making it a complex health issue to address. At the most basic level, it is the result of an energy imbalance. Simply stated, we eat too much and exercise too little.
- Energy is another word for calories. Whenever you eat or drink, ENERGY (in the form of calories) is coming IN. At the same time, your body is constantly working, so ENERGY (in the form of calories) is going OUT. When you are in "energy balance" your energy (or calories) IN equals your energy (or calories) OUT.
To imagine energy balance, think of a scale...
- To maintain a healthy weight, your energy IN and OUT do not have to balance exactly every day. It is the balance over time that helps you maintain a healthy weight.
- The same amount of energy IN and energy OUT over time leads to a stable weight, that is, your weight stays the same:
- More energy IN than energy OUT over time = weight gain
- More energy OUT than energy IN over time = weight loss
Estimated Calorie Needs Per Day by Age, Gender, and Physical Activity Level7
The estimates are rounded to the nearest 200 calories. An individual's calorie needs may be higher or lower than these average estimates.
People today work harder and take better care of their health than any previous generation. So how could two-thirds of us fail to measure up when it comes to eating right and exercising? HBO and the Institute of Medicine of the National Academy of Sciences have joined together to bring you the nation's foremost experts and definitive research on weight and weight loss. The Weight of the Nation explains how we got to this unhealthy place and how we can get to a healthy weight by overcoming the forces that drive us to eat too much and move too little.
Three years in the making, The Weight of the Nation answers crucial questions about yo-yo dieting, how metabolism functions, why stress affects weight, and how to keep weight off forever. Based on the rich research behind HBO's documentary series, The Weight of the Nation is the only book that tells it like it is: Losing weight is hard, keeping it off is even harder, and there's no quick fix. Weight loss takes a lot of work and a lifetime commitment, but thousands have done it and this book will show you how.
Chapter 1 - The Bad News: We Have a Big Problem
As much as we all wish there were one thing in the fight against fat we could point to and eliminate, there isn't. Whether you look at individuals or at our society as a whole, the cause is complex. It's the sum total of all our little daily decisions that results in us eating a little too much and moving too little-which over time adds up to a lot of pounds. For the nation, our obesity problem has been magnified by the actions of industry, agriculture, and government. These forces shape the environment in which we live, work, and play and, often unintentionally, make it harder for us to make healthy choices. Big decisions made by industry, agriculture, and government have a huge impact on the little decisions we make about what we reach for when we're hungry and how long we sit at our desks and in our cars.
The good news is that, to some extent, there are things within our control that we can change to help ourselves, our families, and our communities pursue healthier lives.
Obesity is not inevitable. It can be prevented. And, with hard work and the right information, it can even be reversed.
We Know We're Fat . . . Don't We?
Our national obsession with stick-thin beauty as portrayed in television shows, movies, and magazines has confused an entire generation about what healthy actually looks like. But, equally concerning are the generations of Americans who now look at the overweight and obese people around them and mistake them for people who are at a normal size and a healthy weight.
So, if our perspective is so distorted, how can we tell when our fat is an actual problem and not just a bothersome muffin top?
How Fat Is Too Fat?
If you're cutting through the fat to try to figure that question out, what are the most important measurements you need to pay attention to? The simple answer is your waist size and your body mass index. The bigger your waist, the more likely you are to be storing an unhealthy amount of fat in your abdomen. Excess fat that accumulates in your midsection is directly associated with your risk of developing the chronic health conditions linked to obesity, so waist size is a critical measurement to know. A quick and fairly accurate way to measure it is as simple as stretching a piece of string around your stomach. Find the circumference of your bare waist just above your hipbones. Men who measure at over forty inches and (non-pregnant) women who measure over thirty-five inches are at risk.
One of the terms that gets used most often in discussions about obesity, weight loss, and weight gain is body mass index, or BMI, which is a ratio of weight and height that represents how much body fat you have. The most important thing you need to know about BMI is that it's the calculation most often used by your physician. It's also valuable to scientists and statisticians, because it's a reliable measure that is easy to figure out. Because BMI is so commonly used, it's crucial to know what yours is. The standard BMI chart is broken down into the following categories:
ADULT (20 years+) BMI CHART
| Underweight | Less than 18.5 |
| Healthy weight | 18.5-24.9 |
| Overweight | 25.0-29.9 |
| Obese | 30 and above |
| Morbidly Obese | 40 and above |
Calculate your own BMI by clicking here.
What Is Fat?
Adipose tissue, the scientific name for body fat, is required for human development and survival. We all need fat for energy storage, metabolism, growth, brain function, temperature insulation, organ protection, and structural cushioning. (Imagine sitting without it!) But adipose tissue is not the only place fat cells live. They're everywhere in your body-in your organs and even in your blood.
The number of fat cells each person has varies: a lean person has around 40 billion, an obese adult might have 120 billion. How many you end up with depends on many things, including genetics, but scientists believe there are three times in your life when you can make a lot of them-the third trimester just before you're born, the first year of life, and during puberty.
Once you've made fat cells and settled at a number, here's the bad news: That number can never get lower again. When you lose weight, you're actually not losing any fat cells. The ones you have are just shrinking. An obese person not only has up to three times more fat cells than someone at a healthy weight who's never been obese, but their fat cells themselves can be twice as large as the fat cells of a lean person. Lose weight, though, and the cells will contract.
When you consume excess calories and the body has no more empty fat cells to fill, the only thing it can do to store them is to make more fat cells. Many of the health problems that result from the production of these additional fat cells are caused by the fact that they are not just under your skin. They are also accumulating inside your abdomen, where they surround your internal organs, and, amazingly and dangerously, within some of those organs, like the liver and the heart. When fat begins to accumulate inside your organs, it dangerously disrupts your metabolism.
To be healthy, the body of an average (read: non-marathoner) adult woman should be about 21 to 31 percent fat. The body of a healthy, average (read: non-NFL linebacker) adult male should be roughly between 14 and 24 percent fat.
Still, BMI isn't a perfect measurement of our body fat or of our risk for related health conditions. For example, highly competitive athletes tend to have higher BMIs because of increased muscle mass. For the vast majority of us, though, our BMI reflects our level of body fat and our health risks. While the BMI chart is the same for men and women, BMI calculations for children take into account their growth and development and should be determined by a pediatrician at every visit. If the result concerns you and your doctor, you should discuss both its implications and what you can do to help your child.
What may surprise you is that you don't need to have a BMI in the obese range to start developing the adverse health outcomes related to carrying too much weight. Being even a few pounds overweight can start you down the path to type 2 diabetes- and you can tip over into type 2 diabetes without ever becoming obese.
The Growing Majority
So how does the rest of the population look?
According to the CDC's most recent survey of America's health, released in January 2012, almost 32 percent of 2- to 19-year-olds and nearly 69 percent of adults in America are overweight or obese.
In 2010, the obesity rate for adults rose in sixteen states. And how many states saw a decrease? None. While it's true the rate of increase has begun to slow, that doesn't mean we're out of the woods yet.
The obesity epidemic is like a flood. The rush of water may have abated, but our nation is still more than two-thirds underwater. And in some demographic groups and income brackets, the floodwaters are still pouring in. Ever since 2005, there is no longer a linear relationship between poverty and obesity. Being wealthy is not nearly as protective against obesity as it used to be.
Being overweight or obese isn't just uncomfortable-it's also deadly, as obesity is far too often followed by a wave of chronic disease. But the obesity epidemic is not a natural disaster that we can't do anything about. Unlike a tsunami, this national crisis is completely preventable.
From The Weight of the Nation by John Hoffman and Judith A. Salerno, M.D., M.S. with Alexandra Moss. Copyright © 2012 by the authors and reprinted by permission of St. Martin's Press, LLC.
Sources for Quotes Marked with Asterisks in The Weight of the Nation Book:
p. 72: Dr. Gene-Jack Wang, a neuroscientist at Brookhaven National Laboratory, isn't surprised about the possible similarities between junk food consumption and drug use. "We make our food very similar to cocaine now," he says. "We purify [it]. Our ancestors ate whole grains, but we're eating white bread. American Indians ate corn; we eat corn syrup."1
p. 79: Mark Hardison, vice president of El Pollo Loco, concedes that they considered doing away with combo meals as they were introducing healthier options, but guests "overwhelmingly" wanted the combos back. "As long as our guests are getting a good value out of that, we're happy to complete their meal. It makes business more economically viable and our business performance stronger when we do it that way."2
p. 87: When asked about the role of restaurants in contributing to the obesity problem, Steven Anderson, president of the National Restaurant Association, stated, "Just because we have electricity doesn't mean you have to electrocute yourself."3
pp. 103-104: "If we are successful in our efforts to lower prices, we believe we can save Americans who shop at Walmart approximately $1 billion per year on fresh fruit and vegetables."4
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