Want to lose weight? Want to be healthy? You need to understand how your body uses sugar (carbohydrates) and what sugar does to your body.
Sugar And Energy
Simple sugars in foods include the monosaccharides glucose, fructose, and galactose. Disaccharides (compounds made from two molecules of sugar) such as maltose, sucrose (table sugar), and lactose (the sugar in milk) are also generally considered simple sugars. All of these can be converted to glucose in your body. Some sources of simple sugars include fruit, juice, honey, and candy, and processed goods often have sugar added to them. Sources of complex carbohydrates include bread, cereals, grains, pasta, beans, lentils, potatoes, and many others; these complex carbohydrates are all broken down into simple sugars in your body.
Sugar in the form of glucose is one of the major sources of energy in your body, and the primary source of energy in brain cells (under normal conditions). In other words, your body needs sugar. However, it doesn’t have to obtain sugar directly from your diet; your body can synthesize sugar from protein, and it does this automatically when needed. Additionally, your body can derive energy from fat, and the glycerol component of triglycerides (the primary form of stored fat in your body) can also be converted to glucose.
Insulin And Glucagon
In response to high levels of sugar in the blood stream (such as after a meal containing carbohydrates), beta cells in the pancreas release the hormone insulin. Insulin is necessary for normal metabolic function, and it signals cells of your body to take up sugar (and absorb other nutrients such as amino acids—the building blocks of proteins) from your blood stream and either use the sugar for energy, store it as glycogen (glycogen is a long chain of glucose molecules and is the main form in which sugar is stored in your body), or store it as fat. As only a finite amount of sugar can be stored as glycogen, the majority of excess sugar will normally be converted to fat and stored in fat cells (adipocytes).
In opposition to insulin, when blood sugar is low alpha cells in the pancreas release the hormone glucagon. Under normal conditions, glucagon signals your body to increase blood sugar levels by breaking down glycogen into glucose and triglycerides into fatty acids to be used for energy.
Most people eating a western diet consume far too many carbohydrates. When carbohydrates in excess of what are immediately needed for energy are consumed, liver cells convert the excess glucose and other sugars to fat, for storage in fat cells. This occurs any and every time there is excess glucose in the blood stream!
Under normal conditions, as adipocytes store fat, the hormone leptin is produced and released by these fat cells, sending a message to the body that it is full. This message from leptin tells your body to reduce hunger, stop eating, reduce the storage of fat, and increase the burning of fat for fuel. This is a natural and necessary feedback mechanism in your body.
The problem occurs when this feedback mechanism gets overused and, over time, looses its effectiveness. The increased consumption of excess sugar over and over again and the subsequent massive releases of insulin that results—causing the continued conversion of sugar to fat—leads to surges in the release of leptin. Repeatedly subjected to too much leptin, your body eventually starts becoming resistant to leptin and begins ignoring its signals. This is called leptin resistance. With increased resistance to leptin, your body stops paying attention to the messages leptin is trying to convey—to stop eating and start burning fat—and consequently remains hungry and continues storing fat (even though it already has more than enough stored fat).
Through a related mechanism, insulin also directly inhibits the activity of an enzyme called hormone-sensitive lipase, which is responsible for breaking down the fats in adipocytes and releasing these fats into your blood stream to be used for energy. When high levels of insulin inhibit hormone-sensitive lipase, your body’s ability to burn fat is hindered.
Insulin Resistance And Leptin Resistance
Once your body becomes accustomed to always getting its energy from carbohydrates, its ability to burn fat for energy becomes severely depressed. Sugar is used as energy and stored as fat, but the reverse—utilizing fat for energy—rarely occurs; thus, stored fat remains as fat (because it is never used). In other words, insulin inhibits the use of stored fat for energy. If your blood sugar level is high you will not be able to burn fat!
The continuous exposure of your body to too much sugar, and the constant insulin release that occurs, also leads to increased insulin resistance, also called decreased insulin sensitivity. Insulin resistance means that the body begins ignoring the signals of insulin—which normally tell cells in your body to absorb sugar and use it for energy or store it (as glycogen or fat) for use later. When your body begins ignoring insulin, sugar levels in the blood stream rise above normal (hyperglycemia), and it takes ever higher levels of insulin for cells to absorb this sugar. Over time, this chronic condition is not only extremely taxing to the pancreas—which produces and releases insulin—but on your body as well, and can lead to diabetes and other adverse health conditions.
But persistently reoccurring spikes in insulin—and the subsequent insulin resistance, leptin resistance, and inhibition of hormone-sensitive lipase that result—don’t just cause a person store excess sugar as fat. During periods of time when there is not enough blood sugar for energy (as occurs shortly after an insulin spike caused by the consumption of sugar or, conversely, while fasting—including while sleeping and between meals), a person that is insulin and leptin resistant will turn to using glycogen and protein (including the amino acids from muscle) to convert to glucose for energy instead of metabolizing fat. In other words, a person that is insulin and leptin resistant and faced with a need for energy is, in part, more likely than normal to consume his or her own muscle for energy instead of burning fat. This, in turn, increases hunger—further reinforcing a vicious cycle of eating and storing excess energy as fat.
Additionally, leptin is angiogenic, meaning it promotes the growth of new blood vessels—fundamental in the transformation of dormant tumors into malignant tumors. Overweight individuals tend to be resistant to leptin and, consequently, have high circulating levels of leptin—providing a strong link between obesity and cancer.
Sugar Is Toxic
To make matters even worse, sugar is toxic to your body, and high levels of sugar in the blood stream are extremely dangerous! Sugar causes damage to membranes and blood vessels throughout the body; for this reason, your body tries to keep blood sugars levels low. However, with impaired sensitivity to insulin, this is not possible, and high blood sugar levels result. This is the primary reason long-term hyperglycemia (such as that experienced by diabetics and even those in a pre-diabetic state) can cause irreversible damage to blood vessels and other tissues in the body such as eyes, kidneys, and nerves.
Cut Carbs (Sugar)
The goal is to avoid insulin spikes and reverse insulin and leptin resistance—re-training your body to burn fat instead of carbohydrates. The way to do this is to reduce carbohydrate intake, thereby decreasing insulin production. Over time, when the ingestion of carbohydrates is dramatically cut back, your body will be retrained and forced to once again begin utilizing its natural fat-burning pathways.
Low, stable insulin levels are also ideal for sustained energy throughout the day; the lower, and the less your insulin levels fluctuate (such as spiking after your body is exposed to a large dose of sugar and then falling dramatically shortly thereafter and causing lethargy), the better. In fact, the key to losing weight is to maintain low, stable levels of insulin throughout the day so your body can produce large amounts of hormone-sensitive lipase and continuously burn fat.
To accomplish this, pay astute attention to what your body is telling you. Only eat when you are hungry. Cravings—especially for sugar—don’t mean you are hungry! These cravings may be tough to ignore at first, but as you start to eat healthier, exercise, and cut sugar intake, your cravings will slowly diminish as your body adapts to lower sugar and insulin levels. This is a positive signal and indicates your lifestyle change is working!
As a bonus, exercise has been shown to increase insulin sensitivity, thereby decreasing sugar cravings! In fact, as you exercise more you will probably begin to see your yearnings for simple sugars decrease. At the same time, as you reduce the sugar you consume your threshold for sweetness changes, eventually allowing foods with less sugar to taste sweeter. Exercising and avoiding simple sugars will help you achieve your weight loss goals and may even make your food taste better. Of course, if you’re already at your ideal weight, exercise will help you maintain your health.
The dangers of insulin resistance cannot be overemphasized. The more insulin resistant you are, the more excess sugar is left in your bloodstream at all times, causing damage to blood vessels throughout your body—including in organs such as the heart and lungs, the eyes, and almost everywhere else. Sugar also decreases your immune system’s ability to prevent illness and fight infection. Keeping blood sugar at reasonable levels can significantly decrease your risk of kidney disease, blindness, atherosclerosis, heart disease, and many other adverse health effects. Circulating sugar is damaging to your body; keeping it at as low a level as possible will help you stay healthy.
Furthermore, low blood sugar levels (and therefore lower insulin levels) are one of the keys to a long life. In fact, of all the centenarians (people 100+ years old) in the world, across ethnicities and countries, the single commonality is low blood sugar! Avoiding simple and refined sugars, and thereby increasing your body’s insulin sensitivity and decreasing insulin levels, will dramatically increase the length and quality of your life!
Avoiding simple carbohydrates (simple sugars) is perhaps the most important rule to follow in losing weight. Sugar consumption causes the release of insulin, which signals cells of your body to absorb sugar and store it as either glycogen or fat. Leptin signals your body it is full and should start burning fat for energy. Hormone-sensitive lipase breaks down stored fat for use as energy and is activated by glucagon (when your blood sugar levels are low). Repeatedly exposing your body to excess sugar will, over time, lead to insulin resistance, leptin resistance, and the inhibition of hormone-sensitive lipase. This state not only makes it very difficult to burn stored fat for energy (and thus lose weight), it also makes your body more likely to break down muscle for energy. Furthermore, insulin resistance results in constantly high blood sugar levels—which can cause many harmful health conditions including atherosclerosis, heart disease, diabetes, and damage to blood vessels and tissues throughout your body.
Remember, when first cutting carbohydrates and shifting to the burning of stored body fat for fuel, you may feel lackadaisical and have strong cravings for carbohydrates. These cravings are normal (you don’t have to eat carbohydrates) and will subside as your body adjusts to burning fat. Reducing the intake of carbohydrates helps keep your insulin levels low—which decreases your creation of body fat, escalates your burning of dietary fat, and increases your use of stored fat for energy.
Finally, manufacturers often add multiple different simple sugars to a single food product, which may push each of these sugars down the ingredients list (which lists ingredients in order from greatest to least amount present in the product). Be aware of how much total sugar is in a product by checking the Nutrition Facts label. Of course, eating whole, natural, minimally-processed foods when possible is ideal.