4.5: Factors Contributing to Obesity

Although weight is often simplified to the Calorie Balance equation, it is much more complicated than just the amount of energy consumed versus expended. There are many factors that contribute to overweight and obesity. Some factors can be changed, such as unhealthy lifestyle habits and environments, and others cannot be changed, such as age, family history and genetics, race and ethnicity, and sex.

Unhealthy Lifestyle Factors

We make healthy and unhealthy choices everyday and many of those choices impact our likelihood of becoming overweight or obese. These include: Lack of physical activity, unhealthy eating patterns, not enough sleep, and high amounts of stress.

• Lack of physical activity
  • Lack of physical activity increases your risk of obesity and type 2 diabetes. Strong scientific evidence shows that physical activity helps people maintain a stable weight over time and can reduce the risk of excessive weight gain and the incidence of obesity.
  • Healthy lifestyle changes, such as being physically active and reducing screen time, can help you aim for a healthy weight.
• Unhealthy Eating Behaviors/Unhealthy Diet Patterns
  • Some unhealthy eating behaviors can increase your risk for overweight and obesity.
    • Eating more calories than you use.
    • Eating too much saturated and trans fats
    • Eating foods high in added sugars
    • Not eating enough Fiber
• Not enough sleep
  • Many studies have seen a high BMI in people who do not get enough sleep. Some studies have seen a relationship between sleep and the way our bodies use nutrients for energy and how lack of sleep can affect hormones that control hunger urges.
• High amounts of stress
  • Acute stress and chronic stress affect the brain and trigger the production of hormones, such as cortisol, that control our energy balances and hunger urges. Acute stress can trigger hormone changes that make you not want to eat. If the stress becomes chronic, hormone changes can make you eat more and store more fat.

Environmental Factors

Geography, food availability, transportation, and work environments are environmental factors that can increase your risk for overweight and obesity^[7].

• Geography
  • Where you live may impact your risk of obesity. In the U.S. the South and the Midwest having the highest level of obesity among adults. There is also an increase in BMI in rural areas that is which is said to be contributing to approximately 55% of global increases in BMI. The increase of BMI in rural areas may be due to having farther distances between residences and supermarkets, clinical settings, and recreational opportunities.
• Food Availability
  • The food that is available in your community may impact your risk of obesity. Historical data has shown a relationship between the amount of fast food available in a community and the rate of obesity. The lack of affordable healthy food is termed a “food desert.” Communities that have been designated as a “food desert” have higher rates of obesity. The ease and availability of high sugar drinks, large portion sizes, and highly processed snack foods all relate to increased risk of obesity.
• Transportation
  • How your community is designed may impact your risk of obesity. A neighborhood purposefully developed to allow for people to be able to walk instead of drive reduces your risk of obesity; High neighborhood walkability has been found to be associated with decreased prevalence of overweight and obesity. Neighborhoods that provide recreational facilities, access to sidewalks and paths that remove pedestrians from traffic hazards, and access to parks, have all been reported to be facilitators of physical activity.
• Work Environment and Advances with Technology
  • Have you considered how jobs have changed with the advances in technology? From 1960 to 2010, jobs in the U.S. private industry shifted from 50% requiring at least moderate to vigorous physical activity to less than 20% requiring this level of activity intensity^[8]. National Health and Nutrition Examination Survey data has documented an association between decreases in work-related energy expenditure and weight gain over the same time period. The changes in energy expenditure may be due to advances in technology, an easy example is the use of email to quickly transmit documents rather than walking them to a colleague.

Individual Factors

Although environmental factors have been shown to impact obesity rates, people can have the same environmental factors and still have variances in obesity, fat distribution, and health issues. Thus, it is important to understand how individual characteristics, such as their genetics, impact their risk of obesity.

• Race or Ethnicity
  • Some racial and ethnic minority groups are more likely to have obesity. Rates of obesity in American adults are highest in blacks, followed by Hispanics, then whites. This is true for men or women. While Asian men and women have the lowest rates of unhealthy BMIs, they may have high amounts of unhealthy fat in the abdomen, which as an increase risk for cardiovascular disease and diabetes. Samoans may be at risk for overweight and obesity because they may carry a DNA variant that is associated with increased BMI.
• Sex
  • In the United States, obesity is more common in black or Hispanic women than in black or Hispanic men.
  • A person’s sex may also affect the way the body stores fat. For example, men store more unhealthy fat around the abdomen than women.
  • Overweight and obesity is also common in women with polycystic ovary syndrome (PCOS). This is an endocrine condition that causes large ovaries and prevents proper ovulation, which can reduce fertility.
• Age
  • Many people gain weight as they age. The risk of unhealthy weight gain increases as you age. Adults who have a healthy BMI often start to gain weight in young adulthood and continue to gain weight until 60 to 65 years old, when they tend to start losing weight.
  • Childhood obesity remains a serious problem in the United States and children who have obesity are more likely to have obesity as adults.
• Genetic Influences
  • The relationships of genetics to obesity has been studied for over 100 years. Although over 50 genes have been shown to have an association with obesity, in most obese people, no single genetic cause can be identified. In a study comparing identical and fraternal twins who either grew up together or apart showed that their genetics was more substantially related to their BMI than the environment that they grew up in^[9]. Most obesity seems to be multifactorial, that is, the result of complex interactions among many genes and environmental factors.
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• Medical Conditions
  • Several genetic syndromes are associated with overweight and obesity, including Prader-Willi syndrome, Bardet-Biedl syndrome, Alström syndrome, and Cohen syndrome

• • Endocrine disorders, such as hypothyroidism and cushing’s syndrome also impact overweight and obesity.
  • Medical problems, such as arthritis, also can lead to decreased activity, which may result in weight gain.
• Medicines
  • Some medications can lead to weight gain, these include: antipsychotics, antidepressants, antiepileptics, and antihyperglycemics.