Insulin resistance has become increasingly prevalent in the United States and is a common precursor to the development of type 2 diabetes. Although the development of insulin resistance is complex, overconsumption of certain foods may also contribute. Foods high in simple sugars tax the insulin-producing cells of the pancreas, which may stimulate appetite and lead to overall overconsumption of calories --- a key contributor to the development of insulin resistance. In addition, foods containing trans fats interfere with normal cell function and may worsen insulin resistance in insulin-resistant individuals. Finally, high-calorie foods containing fructose may interfere with the appetite-suppressing hormone leptin and lead you to overeat.
Physiology of Insulin Resistance
When you eat a meal, your blood glucose rises. Your body detects this increase in blood glucose, and as a result, your pancreas secretes insulin into the bloodstream. The insulin proteins bind to the cells in tissues throughout the body, such as muscle and liver. Insulin binding stimulates a complex signaling sequence that promotes the tissue to take up glucose. This clears the glucose out of your blood and provides the tissues with fuel. However, if you are insulin-resistant, your tissues cannot respond to insulin as well, which reduces the ability of glucose to get into the tissue.
Simple Sugars
Your blood glucose increases rapidly when you eat simple sugars such as candy, soft drinks or baked goods. This requires your pancreas to produce a large amount of insulin in response, which taxes the insulin-producing cells of the pancreas. The large insulin response will also lead to a rapid drop in your blood glucose levels, causing you to feel hungry and tired. This may encourage you to eat more sugary food to quickly restore blood glucose levels and lead you to overeat. Even short-term overeating in lean individuals increases insulin resistance, according to a 2009 study published in "Molecular Medicine."
Trans Fats
Trans fats, found in many processed foods including crackers, chips and baked goods, may also lead to insulin resistance by interfering with normal cell function. Trans fats have an abnormal structure, which your body responds to by increasing inflammation. This may interfere with the insulin-signaling pathway, particularly in individuals susceptible to insulin resistance. A 2005 study published in "Metabolism" showed that overweight individuals with a gene predisposing them to insulin resistance had higher insulin levels after eating a meal high in trans fats compared to a meal high in unsaturated fats.
Fructose
Overconsumption of fructose, a type of carbohydrate that exists naturally in fruit and has been added to many processed foods, may lead to overconsumption of calorie-dense foods by altering levels of appetite-regulating hormones. A 2004 study published in "The Journal of Clinical Endocrinology and Metabolism" showed that individuals had lower levels of leptin, a hormone that causes you to feel full, after drinking a fructose drink versus a glucose drink. Fructose is almost exclusively broken down in the liver and does not trigger as great an insulin release from the pancreas as glucose. Insulin release increases leptin activity. Furthermore, many calorie-dense processed foods contain high-fructose corn syrup, which can lead to overconsumption of total calories due to the lack of appetite-suppression.
References
- "Molecular Medicine"; Short-term Overeating Induces Insulin Resistance in Fat Cells in Lean Human Subjects; A. Danielsson et al.; July-August 2009
- "Metabolism"; Comparison of the Acute Response to Meals Enriched With Cis- or Trans-fatty Acids on Glucose and Lipids in Overweight Individuals with Differing FABP2 Genotypes; M. Lefevre et al.; December 2005
- "Journal of Clinical Endocrinology and Metabolism"; Dietary Fructose Reduces Circulating Insulin and Leptin, Attenuates Postprandial Suppression of Ghrelin, and Increases Triglycerides in Women; K.L. Teff et al.; June 2004
