Understanding The Weight Loss Epidemic
By: Kristy Haugen
Diabetes is becoming an epidemic in the younger generation. Type 2 diabetes is the most frequently diagnosed because of our lifestyles. With the growing popularity of this health condition, we need to understand how diabetes affects our health and how we can prevent diabetes.
Energy metabolism is controlled primarily by the actions of two hormones: insulin and glucagon. Any change in circulating levels of these hormones allows the body to store energy when food is available or to make stored energy available when food is not. The hormones insulin and glucagon profoundly affect the body’s energy metabolism. Let’s further explore these hormones and how they function in the body.
Insulin is a peptide hormone composed of 51 amino acids arranged in two polypeptide chains. This hormone is produced and secreted by the beta cells located in the islets of Langerhans within the pancreas. Insulin effects glucose metabolism in three prominent tissues: liver, muscle, and adipose (fat).
Insulin stimulates the uptake of glucose by muscle and adipose cells. Insulin stimulates the storage of glucose as glycogen in muscle and liver cells. Insulin also stimulates the synthesis of fats from glucose and the uptake of amino acids. Insulin opposes the actions of the hormone glucagon, similarly as glucagon opposes the actions of the hormone insulin. This response is somewhat like a tug of war between the two hormones.
High levels of blood glucose stimulate the secretion of insulin. Insulin has a plasma half life of about six minutes. This permits rapid changes in circulating levels of insulin.
Type 1 diabetes is characterized by an absolute deficiency of insulin. Type 1 diabetes is an autoimmune disorder that attacks the beta cells of the pancreas. The islets of Langerhans become infiltrated with activated T lymphocytes. This leads to a condition called insulitis. Over time this attack leads to depletion of beta cells in the pancreas. The pancreas will then fail to respond to ingestion of glucose. Type 1 diabetes is referred to insulin-dependent diabetes mellitus.
Type I diabetes symptoms only appear after 80-90% of the beta cells are destroyed. This is why the onset of type 1 diabetes is during childhood or puberty. Common symptoms of type 1 diabetes include excessive thirst (polydipsia), excessive hunger (polyphagia), and frequent urination (polyuria). Other symptoms that usually accompany the above symptoms include fatigue, weight loss, and weakness.
Glucagon is a peptide hormone produced and secreted by the alpha cells located in the islets of Langerhans within the pancreas. Glucagon is composed of 29 amino acids arranged in a single polypeptide chain. Glucagon stimulates protein and fat degradation, the conversion of glucose to glycogen, and biosynthesis of new glucose (not from glucagon).
Glucagon functions to increase blood glucose levels. Secretion of glucagon is stimulated by a decrease in blood glucose and gastrointestinal hormones. Elevated blood glucose and insulin both decrease the secretion of glucagon.
The increasing prevalence of obesity and sedentary lifestyles in the U.S. has increased the incidence of type 2 diabetes. Not only is the increased incidence of type 2 diabetes affecting adults but children as well. Type 2 diabetes is more commonly seen than type 1 diabetes. Type 2 diabetes affects approximately 90% of the American diabetic population.
Type 2 diabetes typically develops gradually over time. There are no obvious symptoms and is usually detected during routine office visits. Many individuals have frequent urination (polyuria) and excessive thirst (polydipsia) for several weeks. Excessive hunger (polyphagia) in the type 2 diabetic is less common.
Type 2 diabetes is caused by a combination of dysfunctional beta cells and insulin resistance. Insulin secretion in the type 2 diabetic is simply not adequate. Insulin resistance is the decreased ability of the target tissues to respond to normal circulating insulin levels. Type 2 diabetes is commonly referred to as non-insulin-dependent diabetes mellitus. Obesity is more commonly the cause of insulin resistance. However, most obese people with insulin resistance do not become diabetic. The absence of the defective beta cell function in the obese non diabetic individual can compensate for insulin resistance by secreting elevated levels of insulin.
Insulin resistance alone will not cause type 2 diabetes. In order for someone to develop type 2 diabetes, they must also show impaired beta cell function. Insulin resistance increases with weight gain and decreases with weight loss, suggesting that fat accumulation helps with insulin resistance development.
Type 2 diabetes is becoming an epidemic due to increased obesity and sedentary lifestyles. Children are now developing this disorder. Changing the diet to include healthier foods such as fruits and vegetables along with implementing a regular exercise plan is a great start. Diabetes is a serious disorder that many believe will not strike them. Don’t wait to find out, start this year with a change!
References
- Holford, Patrick. The New Optimum Nutrition Bible. Berkeley,California. The Crossing Press. 2004.
- Champe, Pamela C; Harvey, Richard A; and Ferrier, Denise R. Lippincott’s Illustrated Reviews: Biochemistry. 3rd ed. Lippincott Williams &Wilkins. Philadelphia, Pennsylvania. 2005.
- McKinley, Michael P. and O’Loughlin, Valerie Dean. Human Anatomy. 1st ed. New York, NY. McGraw-Hill. 2005.
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