Honestly, carbohydrates are easily my favorite food group. Ask anyone who knows me what my food weakness is, and they’ll tell you, potatoes. But, low-carb diets gained public attention in the early 2000’s with the sudden popularity of the Atkins Diet, originally developed in the 1960’s. This continues today with the emergence of the paleolithic and ketogenic diets. So, what’s the deal? Do carbs lead to dietary detriment, or are they a harmless addition to your plate? As you probably guessed, it isn’t a black and white question. So to kickstart our discussion of this macronutrient I’m simplifying the science.
The Science of Blood Sugar
The breakdown of carbohydrates results in glucose. Glucose raises blood sugar and in response to this elevation the pancreas produces insulin, a storage hormone that helps transport glucose into cells. Otherwise stated, insulin helps maintain the balance of intra- and extra- cellular glucose.
There are three types of cells that can receive glucose: liver cells, muscle cells, and fat cells. For visual learners I like to use a purse analogy.
- I compare liver cells to a crossbody. Just as a crossbody is a small bag, the liver only stores up to 500 calories of glucose as glycogen.
- Muscle cells can retain a bit more, up to 2,000 calories, so I refer to them as a backpack. If your muscles are at capacity, exercise is the only way to make room for more glucose. Chronically elevated blood sugar levels cause muscle cells to become desensitized to insulin. This harmful phenomenon, called insulin resistance and it leads to the third purse.
- Any leftover glucose is stored as triglycerides in fat cells, or in my analogy the bag from Mary Poppins. Just as the eccentric nanny could pull anything from her bag, fat cells have no maximum capacity. That means that when glucose isn’t being used as fuel, it is converted to fat!
The Glucose Roller Coaster
A healthy blood glucose ranges from 70 to 120 mg/dL. If you’re eating carbohydrate heavy snacks and meals, your blood sugar will spike higher and faster causing the pancreas to release proportional amounts of insulin. Unfortunately, if your crossbody and backpack are still full due to your last meal, the glucose will be stored as fat or remain in the bloodstream. In this situation your body’s fat burning mechanisms will be turned off because insulin is a storage hormone. Your body will not burn fat if it is receiving signals that it is in storage mode.
Furthermore, like a roller coaster what goes up must come down. A spike in blood sugar is followed by a crash. Whether this happens fast or slow, when your blood sugar eventually falls you will crave more carbohydrates because they’re the fastest source of glucose. If your body is tricked into thinking you’re starving because of the lingering insulin in your bloodstream, hormones make you crave the quickest fix. This can occur even if your blood sugar level is normal, and you ate less than two hours ago. Think of this equation: decreasing blood sugar + excess insulin in your bloodstream = carbohydrate cravings.
Health Implications
Consistently elevated blood sugar leads to a host of health woes including Diabetes mellitus, metabolic syndrome, chronic inflammation, autoimmune diseases, and digestive problems due to gut dysbiosis. It is no secret that the obesity epidemic is a crisis. However, you do not have to be overweight to experience the previously mentioned health problems. This may make you fearful of eating another carbohydrate. But remember just like fat, not all carbohydrates are created equal. Health enhancing options do exist. Unfortunately, in the setting of the standard American diet, processed foods and refined grains high in sugar (and those inflammatory oils I discussed in The Skinny on Fats: Part II) replaced whole-food, nutrient-dense options. In the upcoming weeks I will discuss different types of carbohydrates and how I personally approach incorporating this food group in my diet.