Insulin is one of the main energy regulatory hormones in the body. It helps maintain blood glucose levels, blood fatty acid levels, and plays a role in hunger sensation. When blood sugar rises, insulin is released from the pancreas. Insulin stimulates muscle and fat cells to take up more glucose, therefore maintaining blood glucose levels in a normal range. Elevated insulin levels also inhibit adipose (fat) cells from releasing fatty acids. Over time, cells become resistant to chronically elevated insulin levels (from elevated glucose levels) and don't take up blood glucose as regularly. Thus, blood glucose levels rise and symptomatic, clinical diabetes develops.
Most people are aware of the rising rate of diabetes and obesity in the US. One of the main reasons is the growing content refined grains in our diets. For example, females consumed 51.6% of their Calorie intake from carbohydrates (mostly refined) in 2000. Contrast this to 45.4% in 1971. At the same time, fat Calorie intake dropped from 36.1% to 32.8% during the same period. Oh, and coincidentally, obesity rates doubled! (U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Health Statistics).
Refined carbohydates are everywhere in the American food source. Just about every food sold in fast food outlets, restaurants, and grocery stores are refined grains (wheat, corn, rice, or soy). Consider foods like soda, juice, bread, cereal, pasta, chips, and even ketchup, and salad dressing are full of refined grains. Again, upwards of 50% of our Calorie intake is from these refined sugars that provide little nutritional value, enter the blood stream quickly, raise insulin levels, and keep us hungry.
We don't handle high concentrations of carbohydrates very well. Our physiology has evolved over thousands of years to handle very-low concentrations of carbohydrates. Ironically, what we think of a low carb diet today, was actually a very-high carb diet to our hunter gatherer ancestors!
What about whole grains? Whole grains do provide significant nutrition, including protein, B-vitamins, zinc, vitamin E, and essential fatty acids. Problem is, no one eats these. In fact, it is very hard to find true whole grains. When was the last time you ate wheat berries, quinoa, or steel cut oats? Many processed foods (cereal, bread, and pasta) claim to be made from whole grains. And they are. Just, they are not whole grains anymore after being processed. Any processing, even mechanically grinding the fruit (of these plants from the monocot or grass family), destroys the nutritional content. Typically, the flour consists of mostly the endosperm, and not the bran (outer shell) or germ ( where all the vitamins and fatty acids are located).
Recently, cheaper sweateners have been added to our foods, including the notorious high-fructose corn syrup. Don't be fooled by their claims of it being 'all natural'. That means nothing. Caffeine, ephredrine, tobacco, and cannabis are also 'all natural', but you don't want to consume them as 50% of your diet! Interestingly, Pepsi, sensing the the public's increased disdain for high-fructose corn syrup, started marketing 'throw-back' versions of Pepsi and Mountain Dew with 'natural sugar' (sucrose).
Our bodies can't handle high concentrations of carbohydrates very well. We have an innate craving for sweet tastes. This was valuable for humans for thousands of years when very few food sources contained concentrated carbohydrates. However, now you can't escape processed carbohydrates. They are cheap, subsidized and endorsed by the government, and addicting. But, if you want to lose body fat, stave-off chronic disabling diseases, and feel good, it is imperative that you keep insulin levels low. Remove refined grains from your diet. Eat fresh vegetables, fruits, nuts, and real, unprocessed whole grains (quinoa), natural, cage-free, roaming animals, cage-free eggs, and deep sea fish.