Why is America Overweight? The Role of Hormones on our Insatiable Appetites
Why is America overweight? Current research suggests it may be more complicated than just an overabundance of calories. The types of food we eat may affect our appetite hormones, making us 
hungrier than we were before.
The “gut-brain axis,” is a term which refers to the lines of communication between the brain and the gut that determine the amount of food we eat. The major nerve involved is the sensory vagus nerve. Seeing, smelling and tasting food causes the brain to send signals to the stomach to eat more. Physiological changes in the stomach and small intestine that occur during digestion cause signals to be sent to the brain to produce feelings of fullness and decrease appetite. The balance of these opposing signals is what determines the amount of food consumed (Schwartz, 2004).
There are several hormones involved that determine our appetite. They include:
- Leptin: Leptin is a hormone that is actually released by your body fat stores that decreases hunger. Leptin levels help to determine your “set-point” weight over the long term, or the general weight your body wants to be. Increased leptin levels lead to decreased hunger and food intake.
- Cholcycstokinin & GLP-1: These peptide hormones are excreted by the gut in response to the presence of nutrients entering the intestine. They send signals to the brain to slow digestion, induce satiety and decrease food intake.
- Ghrelin: This hormone is made by the stomach cells and acts to stimulate hunger. Levels rise steadily up until a meal is consumed, and then levels drop after a meal is consumed.
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The types of food that we eat can affect the balance of these hormones. Excess fructose in the diet, for example, has been named as a potential cause of satiety hormonal imbalance as it reduces leptin fails to suppress ghrelin- which leads to an increased appetite (Wylie-Rosett, 2004). Fructose is abundantly found not only in high fructose corn syrup, but also in normal table sugar (sucrose). The fact is we eat too much of it in America, in the form of candy, sweets and sugary beverages.
The best ways to suppress your appetite hormones? Eat balanced meals containing complex carbohydrates (like those in whole grains, vegetables and beans), healthy fats (olive oil, nuts) and protein. Also, drink plenty of water and get adequate sleep.
References:
Schwartz, GJ (2004). Biology of eating behavior in obesity. Obes Res. 2004;12:102S–106S.
Wylie-Rosett J, Segal-Isaacson CJ, Segal-Isaacson A (2004). Carbohydrates and increases in obesity: does the type of carbohydrate make a difference? Obes Res. 2:124S-9S. Review.
This is great information for the general population! I work in the area of diabetes, obesity and CVD, and I truly understand the need to educate everyone on the dangers of consuming too much sugar! I think as a nation we have become very aware of the dangers surrounding the consumption of too much saturated fat, but in return we forgot what seems to be a more important threat. I work with researchers doing fructose studies and I can clearly see the effects that it has on obesity, in turn leading to diabetes and heart disease, and it must be acknowledged and the gap must be closed between what is happening in research and patient education.
Thanks again!