I arrived at this youtube from a posting by Chefgerry here, which says in part:
The body breaks down carbohydrates into simple sugars (monosaccharides) which then get converted to glucose. The liver has a major role within the body for the storage and distribution of all fuels, including glucose. There’s three ways glucose is used.
1) The first and most direct way glucose is managed is in the blood for the production of ATP which every peripheral tissue uses as energy with the brain generally taking up over 70% of all glucose production from carbs for it’s fuel and secondary uses go to muscle and red blood cell production which is essential for oxygen transportation.
2) Glucose is stored in the muscle and liver as glycogen with the help of insulin. When we consume carbs our blood sugar levels go up which signals the beta cells in our pancreas to release insulin to shuttle the excess glucose into our muscle or liver as stored glycogen, and when our blood sugar drops the alpha cells in our pancreas signal glucagon to convert glycogen back into glucose and release back into the blood stream which keeps our blood sugar within a narrow but healthy range. Also keep in mind when glycogen is transported back into the bloodstream and converted to glucose, it coming from the liver…..muscle glycogen cannot be converted into blood glucose, it’s used exclusively for muscle energy.
3) Glucose is converted to fatty acids and stored as triglycerides in adipose tissue. As a side note, the over consumption of carbs in the diet can lead to a condition called hypertriglyceridemia, which paradoxically is where carbs generally displace dietary fat. Also elevated triglycerides in the blood is a risk factor for metabolic syndrome, heart disease, elevated VLDL and the lowering of HDL etc.
So basically what happens when we eat a meal that has a lot of carbs in it is, it gets used as immediate energy, gets stored as glycogen in the muscle and liver and any excess carbs get converted to triglycerides and stored. This happens on a continual basis with every meal where excess carbs are present and in the presents of the hormone insulin. In between meals when blood sugar inevitably drops the hormone glucagon has an opposing effects, causing the release of glucose from glycogen into the blood stream along with the release of fatty acids from stored triglycerides and the stimulation of gluconeogenesis, and this is a normal course of action taking place on a continual bases, over and over again. Actual carry over storage of glucose production to triglycerides would need to exceed daily needs or basically with a surplus of dietary calories.
Carbohydrates have many classifications or descriptions that are sometimes confusing and a few of those examples are monosaccharides or polysaccharides commonly referred to as simple or complex carbs. Another popular description is refined and unrefined and of course there’s the terms sugars, starches and fiber. Personally I really don’t care what we classify or call carbohydrates in general because the only thing that matters is to understand how and why a particular carbohydrate effects our serum blood sugar levels at any given time, period. From this data it will become obviously clear which carbs are better to consume for better control of blood sugar.
To understand how a carb influences our blood sugar levels we have to look at how it’s measured. The Glycemic Index (GI) is one way to do that (2)(3). The GI uses a scale from 0-100 indicating how a single serving of 50g’s of carbs are absorbed. Glucose is used as a measuring stick with a value of 100. The GI also categorizes carbs into 3 groups, high GI food 70+, medium GI food 55-69 and low GI food 54 or less. To test how 50g’s of carbs influence blood sugar they use groups of people that don’t eat for at least 8 hours (fasted state) and feed them 50g’s of a particular carb and nothing else…..makes sense, well not really. The smaller the portion of carbs in a particular food the more of that food they have to consume to get 50g’s. For example we’ve all heard that watermelon is a high GI carb, well it is and is rated at 72, but you would have to eat 1.3 lbs. of watermelon to get to 50g’s of carbs. 2 oz of spaghetti which is a low GI food (38), which should be a typical serving is just under 50g’s… who do you know eats 1 cup of spaghetti, not many. As you can see it can be confusing so a better method of measuring would be to calculate the carb content in a serving of food, which is referred to as the Glycemic Load (GL). The basic calculation for the GL of a food is to multiply the GI of the food by the amount of carbs available, then divided by 100. For example the spaghetti would be 38*43 / 100 = 16. Foods like carrots and watermelon are very low in GL, in the 2 or 3 area….The GL index shows under 10 to be low, 11-19 medium and 20 and up to be high. To confuse the issue further we generally eat more than a single food (carb) for any given meal, or at least we should. Consuming protein, fat, fiber, acids like vinegars all slow gastric emptying (digesting) lowering the rise of blood sugar. You can also reduce the GL of your diet by reducing the GI of the foods you eat and lowering the carb content.
Both Chefgerry and Dr. Lustig speak a bit about the differences between refined sugars and natural sugars found in whole foods. Perhaps the most basic difference between refined sugars and natural sugars is that refined sugars deliver their sweet calorie hit without the fiber, vitamins, minerals, and antioxidants that come along for the ride when we get our sugars from natural sources such as a piece of fruit.
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