Do We Need Fat?
Fat is a nutrient and actually crucial for normal
body function. Without it we could not live. Not only does fat supply
us with energy, it also makes it possible for other nutrients to do
their jobs. Our body is constantly creating and destroying fat cells, but
the body maintains a fixed number of fat cells, which is generally set during
adolescence. However, growth in number can
also occur in adulthood.
How Do We Become Obese?
In adults, the major bulk of adipose tissue (“fat”) is a loose association of lipid-filled cells called adipocytes. Fat cells grow larger than their original size when they fill with lipids, which are a group of fat and fat-like substances, including cholesterol. When our adipocytes fill with lipids and reach a critical size, young, unspecialized cells in our bodies are stimulated to turn into more fat cells, increasing the number of fat cells as a result. So we really have two mechanisms that increase our weight. We can enlarge our existing fat cells, and we can add more fat cells, but we cannot get rid of them.
We can shrink fat cells. We can also enlarge fat cells. Once we reach adulthood, the number of fat cells we have more or less stays the
same. When we put on a large amount of weight, these fat cells enlarge
in size. The opposite holds true when we lose a lot of weight – they
shrink. Weight loss reduces the volume of the fat cell but never reduces the number of fat cells. Preventing the accumulation of fat cells is most important.Prevalence Of Obesity
According to the Centers for Disease Control, obesity rates vary by state, from a low of 20.5 percent in Colorado, to a high of 34.7 percent in Louisiana in 2012, the most recent figures available. In 13 states, obesity rates are equal to or greater than 30 percent. Severe or morbid obesity, marked by a body mass index equal to or greater than 40, was found in 6.3 percent of the U.S. adult population in 2010.Life Expectancy
Obesity in adulthood decreases life expectancy for both men and women, as evidenced by the Framingham Heart Study, a long-term, ongoing cardiovascular study on residents of the town of Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects from Framingham, and is now on its third generation. In the Framingham study, participants age 40 years who were obese lived six to seven years less than those of normal weight. Those who were overweight but not obese at age 40 years lived three years fewer than the normal-weight subjects. Another study called the Prospective Studies Collaboration, which actually was a group of studies that shared information about the link between BMI and health, found that each 5 unit increase in BMI was associated with a significant increase in mortality from each of the following disorders: ischemic heart disease, stroke, diabetes, chronic kidney disease and cancer.
Take a look at the adult (20 years +) BMI table below. It shows us that a woman who is 5 foot 4 inches tall is considered overweight (BMI is 25 to 29) if she weighs between 145 and 169 pounds. She is considered obese (BMI is 30 or more) if she weighs 175 pounds or more. A man who is 5 foot 10 inches tall is considered overweight (BMI is 25 to 29) if he weighs between 174 and 202 pounds, and is obese (BMI is 30 or more) if he weighs 209 pounds or more.Your Lifestyle AND Surroundings Matter
Physical activity — A sedentary lifestyle lowers energy expenditure and promotes weight gain. Of all sedentary behaviors, prolonged television watching appears to be the most predictive of obesity and diabetes risk. Obesity is more prevalent in adults with physical, sensory, or mental health disabilities.
Sleep deprivation — The proportion of adults in the United States sleeping less than seven hours per night has increased from 16 to 37 percent over the past 40 years, a lifestyle change that may have negative metabolic consequences.
Cessation of smoking — Weight gain is very common when people stop smoking. This is thought to be a result of nicotine withdrawal, at least in part. Because of the predictable weight gain after cessation of smoking, it is important to add to your exercise program a decreased caloric intake as part of your lifestyle change.
Social networks — Social influences may affect one's risk of obesity. A report of a social network constructed from the Framingham Offspring Study shows the likelihood of becoming obese increases by 57, 40, or 37 percent in those who had a friend, sibling, or spouse who became obese.
Treatment Is Important
More than two-thirds of adults in the United States are either trying to
lose weight or maintain their existing weight. However, only 20 percent are eating fewer calories and
exercising at least 150 minutes a week (the bare minimum required for weight maintenance).
For initial weight loss, establish a realistic weight loss goal with
emphasis on decreasing total daily caloric intake and increasing energy
expenditure with regular daily exercise. Low-fat and low-carbohydrate diets are recommended, as well as the Mediterranean Diet.
Liposuction, the most common cosmetic surgery in the world, removes a percentage of your total body fat but it doesn’t improve insulin sensitivity or cardiovascular risk. After liposuction, your fat mass will regrow in about a year if you exceed the number of calories recommended for your body type and if you fail to maintain an appropriate amount of physical activity.
Weight loss surgery, also called bariatric surgery, is reserved for people with severe obesity who have not responded to other weight loss treatments.
If you have been overweight or obese for a long time, you may very well have metabolic issues that warrant professional intervention. This is a matter of life and death and should not be taken lightly. Next month we will discuss weight loss in more detail.
Until next time!
Stephanie Coulter, MD
Learn more from the Centers for Disease Control on common questions related to BMI and Obesity:
BMI Percentile Calculator for Children and Teens
How reliable is BMI as an indicator of body fatness?
If an athlete or other person with a lot of muscle has a high BMI, is that person still considered to be overweight?
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