Ever since the beginning of the low/no carbohydrate-dieting fad, carbohydrates have been labeled as the enemy to small waistlines and better beach bodies across the globe. Just like any other nutrition myth, it came from one person giving something a try, succeeding, and then selling it to the public. Good tactic, but where in science does it say that the routine that lead to one person’s success will work for everybody?
Since this low-carb movement, some people have been able to gain an understanding of how it works and use it successfully. However, many people have since neglected any other form of dieting. On top of that, the whole Keto diet was the gasoline to an already lit match, leading to an explosion of myths surrounding the body’s primary source of fuel. Carbohydrates began to only be consumed at certain times of the day (if at all) and only certain types were consumed. Of all forms of carbohydrates, one was given the worst reputation of all. That loan carbohydrate is sugar.
Fructose- How Bad Is It?
Sugar, the sweet component of foods that you may or may not consume (for whatever reason), was deemed an awful source of energy and thus, was avoided at all costs. It was not until people began to realize that glucose (a sugar), the body’s true form of energy, was the end product of all calorie digestion. Once this came to the surface, sugar was considered OK in the fitness world but only in small quantities. But then came the discovery of fructose. Fructose, the common form of sugar in fruit, has minimal differences from other sugars when looking at the grand scheme of things. A slight relocation of the hydroxyl group brings about its altered structure, but it is not the chemistry that raised the red flag; it was the way your body uses it. As we all know, the human body is a masterpiece. It performs in suboptimal situations and has outstanding capabilities. So what was it about fructose that brought about such a scare?
When your body goes through the process of digestion, the conversion of [most] carbohydrates to glucose causes a rise in blood glucose levels and alerts the pancreas to release the hormone insulin enable to allow your cells to successfully use this energy. Insulin does this by shuttling the glucose (energy) into your cells for future use. This energy is stored in the muscles as glycogen and any excess is stored in fat cells. However, do not be alarmed; the body is extremely efficient in returning to homeostasis if you remain within caloric range. This energy will be burned before turning into adipose tissue.
The body handles fructose a little differently; it is metabolized entirely by the liver. That means, instead of being shuttled into the blood and providing the muscles with sufficient energy, fructose replenishes liver glycogen. This, in turn, scared people into thinking that if fructose is consumed, the body will not know what to do with it and, as a response, will store it in fat cells. The idea makes sense and although it is not entirely flawed, it certainly has a couple of aspects that need to be made clear.
Liver Glycogen
The first claim I look to tackle today is the fact that fructose only replenishes liver glycogen and not muscle glycogen. As learned before, when your body digests carbohydrates they are converted to glucose. As a response, the pancreas releases insulin to drive the glucose into cells for use. Fructose, on the other hand, does not elicit the same response. It does not require insulin for storage and thus, is not driven into muscle cells. It only replenishes liver glycogen. The idea behind this argument is that eating large amounts of fructose does not give the body optimal energy for physical performance. The first big flaw in this argument is that when the body runs low on muscle glycogen resulting in lowered blood glucose levels, glycogen from the liver is released into the blood in the form of glucose for use by the muscles. In the end, the fructose becomes glucose anyway.
Fruit – Not All Fructose
Branching off of the topic of liver glycogen replenishment is the content of fructose in foods. People claim that foods containing high amounts of fructose do not adequately fuel the body but rather, just replenish the liver. Looking at the in depth macronutrient breakdown of foods disproves this claim entirely. As an example, let us take a look at one of the most frowned upon forms of carbohydrates that are said to elicit fat storage by those in agreement with the, “No fructose” movement—fruit. I will say that that fruit does indeed contain fructose—fructose is “fruit sugar.” However, the sugar breakdown of an average banana is as follows: 5.03g Glucose, 4.9g Fructose and 2.4g Sucrose. Sucrose is what we call “table sugar” and its chemical structure consists of a bonded glucose and fructose molecule, so think of it as 50% glucose and 50% fructose. With this in mind, we can conclude that a banana contains equal amounts of glucose (6.23g) and fructose (6.1g.) Clearly, glucose is present, so the source of sugar is not entirely fructose, and even if it were, it provides adequate fuel.
HFCS
Another form of sugar that I would to briefly explore while on the topic of fructose content is HFCS (high fructose corn syrup.) It is used widely in processed foods and soft drinks, and with the rise of the fructoseàfat gain epidemic, has scared calorie counters across the globe. Take a good, hard look at the chemical structure of HFCS with me and let’s see if we can arrive at the same conclusion. Before observing the image, know that there are two types of HFCS—one is known as 55/45 and the other is 42/58 (fructose to glucose ratio.)
Either way, it is clear that although the name states high fructose, it contains nearly the same if not more glucose than it does fructose. In conclusion, we can double back to the previous statement about sucrose and apply it to HFCS: it provides adequate fuel.
Calories In vs. Calories Out
A final topic I would like to cover in the big fructose debate relates to the first topic we covered today. Since fructose replenishes liver glycogen, it is thought that when the liver has reached its maximum glycogen capacity it will send whatever extra fructose consumed directly into fat storage. It is true that the liver handles fructose directly, and, through de novo lipogenesis (DNL), converts it to fat when consumed in excess, but this excludes the fact that any form of energy temporarily stored in fat cells is released for later use when one stays within caloric range. If somebody consumes a daily energy intake that puts them in a deficit or at maintenance, regardless if it is stored in fat cells, it will be released and used as energy at some point. The only time one will run into trouble due directly to fructose intake is when it is a majority of the day’s carbohydrate intake. An up end of 15-20 bananas or 6+ cans of soda will put somebody at this amount. Tell me the last time that you saw somebody, especially one who exercises and cares about proper nutrition, go this overboard. Moderation is key.
Finally being able to voice MY opinion on the big fructose debate is not only extremely relieving, but it also helps me rest my head knowing that I am able to ease the minds of my readers that avoid fruit like the plague. There is no reason to avoid any form of carbohydrate. Unless extremely distasteful or too calorie dense for your appetite, any form of carbohydrate can and will eventually lead to fuel for your hard working muscles. And working hard, my friends, is the reason we enjoy this lifestyle; making the decision the live it should not and will not force us to neglect any foods from our diet.
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