Let’s Discuss: Weight Gain & Obesity

Both genetic and environmental factors can affect obesity and weight gain.  According to the CDC, the U.S. has seen an increase trend of obesity prevalence from 1999-2020. Obesity rates increased from 30.5% to 41.9%. Obesity is a growing health concern for the United States and can significantly increase medical costs for Americans struggling with obesity resulting in health complications. This handout will provide a brief understanding of how weight gain and obesity affect the body and why this matters for lifelong health and wellness.

What Makes Us Feel Hungry vs. Full?

There are two main appetite and hunger hormones:

1. Ghrelin – mainly produced by the stomach and signals the brain telling us that we’re hungry and need to eat

2. Leptin. – mainly produced by adipose tissue (body fat) that tells the brain that we’re full and have stored enough energy from food.

Ghrelin controls more of your appetite, while leptin plays a part in weight management and the balance of energy expenditure – meaning that your body shouldn’t signal your brain to eat more food until it has used up the calories from your past meal as energy. Since leptin is produced by adipose tissue, levels of leptin increase when the body gains more fat mass, and vice versa. Low levels of leptin can promote weight gain and obesity because the brain is not being told to stop eating, increasing food consumption. Obesity results in high levels of leptin which can lead to leptin resistance. Leptin resistance causes the brain to be less sensitive to leptin and it doesn’t respond or signal the brain that we feel full. This can trick the brain into thinking we have low levels of leptin, and the body will enter a starvation mode which slows the metabolism but stimulates the feeling of hunger. High levels of ghrelin also promote obesity as it increases the feeling of hunger.

Classifications of Weight

The table below provides the classifications of weight and the body mass index (BMI) ranges that correspond to each classification:

• Underweight

  < 18.5

• Normal

  18.5 - 24.9

• Overweight

  25.0 - 29.9

• Obesity, Class I

  30.0 - 34.9

• Obesity, Class II

  35.0 - 39.9

• Extreme Obesity, Class III

  > 40.0

Why Does Weight Circumference Matter?

Weight gain and obesity and can lead to metabolic syndrome, which is a cluster of symptoms that can increase a person’s risk for chronic disease and other serious health conditions. Having a large waist circumference due to extra visceral fat (fat surrounding the organs) in the stomach region is just one of the symptoms that contribute to metabolic syndrome and lead to other health concerns. Other symptoms include: high blood pressure, high blood sugar, high levels of triglycerides (fat) in the blood and high levels of “bad” cholesterol (LDL cholesterol). All of these symptoms can increase risk of heart attacks, heart disease, stroke and type 2 diabetes. 

3. Apples vs. Pears, (We Dish Nutrition, 2012)

 References:

1. Adult Obesity Facts. Centers for Disease Control and Prevention. May 17, 2022. Accessed December 23, 2023. https://www.cdc.gov/obesity/data/adult.html.

2. Raymond, J. & Morrow K. Krause and Mahan's Food & the Nutrition Care Process.16th ed. Elsevier; 2023.

3. Image. Apples vs. Pears. We Dish Nutrition. Accessed December 23, 2023. https://wedishnutrition.wordpress.com/2014/03/10/apple-vs-pear-shapes/

4. Saklayen MG. The Global Epidemic of the Metabolic Syndrome. Curr Hypertens Rep. 2018;20(2):12. Published 2018 Feb 26. doi:10.1007/s11906-018-0812-z