Carbs, Blood Sugar, and Balancing Macronutrients (Metabolic Efficiency Series Part 2)
My last post ended with the promise that the next post in this Metabolic Efficiency series would discuss how excess carbs and sugar in the diet can lead to health issues and weight gain. So, let’s pick up where we left off…
Carbohydrates are rapidly broken down into sugars in the digestion process. Carbohydrate digestion actually begins in the mouth via enzymes in saliva called salivary amylases. Regardless of whether the carbohydrates come from a whole-wheat bagel, an apple, or a candy bar – they are broken down to sugars in the digestion process. What happens when sugar reaches the bloodstream? Your body has homeostatic mechanisms (“internal control systems”) to maintain a comfortable blood sugar level.
Think of it like the thermostat in your house in the summer: You set the thermostat to tell it what your upper comfort level is for the inside temperature – let’s say that is 72 degrees. When the thermostat detects that the temperature inside the house has reached 72, what happens? The air conditioning kicks on to bring the temperature back to the desired range – less than 72 degrees – where you are comfortable again.
Like the house analogy, your body has a set “comfort level” for blood sugar. When your blood sugar exceeds its upper “comfort limit” following a meal high in carbs/sugars, the body’s homeostatic mechanisms kick in and signal the pancreas, an organ found below the stomach, to secrete insulin. Simply put, insulin is a hormone whose primary function is to help maintain healthy levels of blood sugar with which your body is comfortable. Insulin is released into the blood in response to high levels of blood sugar and it can transport the sugar out of the blood and into 3 main storage locations in the body.
What are those 3 storage locations? Sugar can be transported into the liver and muscle tissue to be stored as glycogen, which serves as your body’s go-to fuel for higher intensity physical activity and for keeping specific systems running efficiently all day (central nervous system, kidneys, red blood cells). This is good, right? Well, sort of. The liver and muscles have a finite storage capacity: only about 1200-2000 calories, depending on gender and body size. Once they’re topped off, they can’t take any more sugar in. Here’s an analogy to illustrate: If your car has a 14 gallon gas tank, you won’t be able to cram 15 gallons of gas into that tank, no matter what you try.
Ready for the bad news? Unlike the liver and muscles, fat cells have an indefinite storage capacity for sugar, so they are able to absorb any of the sugar that wasn’t stored in the liver/muscles. In fat cells, sugar is stored as triglycerides. It is through this mechanism that excessive consumption of carbs and sugars leads to accumulation of body fat.
Eating a high-carbohydrate diet means the pancreas is constantly secreting insulin to try to bring blood sugar level back to its “comfort zone”. This puts a huge strain on the pancreas to produce insulin, and leads to the possibility of a condition known as “insulin resistance”, which means that the body’s cells have become desensitized to insulin, and more insulin is required to have the same effect and transport sugar out of the blood and into storage. Eventually, the pancreas won’t be able to keep up with demand which may lead to excessive sugar building up in the blood and the onset of Type II Diabetes. Another negative impact of chronically elevated insulin levels is that insulin turns off your body’s fat-burning mechanisms. Insulin is known as the “fat storage” hormone, and it actually inhibits the breakdown of stored body fat.
The main idea behind this post is not that all carbs are bad for you, nor is the main idea that insulin is bad. Carbs are required by the body for all kinds of functions, from providing fuel for movement and exercise to providing fuel for the brain, organs, etc to function. Rather, the take-home message here is to be cognizant of carbohydrate choices and portions, and to be aware that excessive levels of insulin for prolonged periods of time is not conducive to overall health and well-being.
To minimize the impact of carbohydrates on blood sugar, there are several things you can do:
The first is to consume carbs with the other macronutrients (see “Golden Rule” below), and not by themselves.
The second is choosing carbohydrates that have a lower glycemic index and therefore enter the bloodstream more slowly (I’m not going to discuss the glycemic index/glycemic load in this post, since it’s already long enough, but information about these can be found through google searches).
Lastly, timing of carbohydrate relative to physical activity is key in preventing excessive carbohydrate storage in fat cells. Physical activity will cause stored glycogen to be broken down for energy; the more intense and longer the duration of activity/exercise, the more glycogen that will be used. Carbs consumed when the muscle tissues and liver are depleted will be converted to glycogen to refill those storage vessels, and carbs in excess of what the liver/muscles can hold will be stored as body fat. So, eating a meal higher in carbs following a workout is better timing, than say, a day you’ve spent sitting at a computer with minimal physical activity (walking to the office printer or to grab your lunch from the fridge doesn’t count as exercise!). In the latter scenario, desk work and minimal physical activity don’t lead to glycogen depletion. Eating a high amount of carbohydrates (whether it’s in the forms of grains or sugars) on a day like this will lead to most of the carbs being stored as body fat since the liver and muscle glycogen stores are pretty much full.
This brings us to what I refer to as the Golden Rule of Metabolic Efficiency: To stabilize blood sugar, think “Protein + Fat^ + Fiber* (carb)” every time: meal or snack.
^Fat has taken a bad rap over the years, but it should not be avoided. Fat has many important functions in our bodies: it serves a hormone precursor, controls the inflammatory response, makes up the cellular membrane of all of our cells, and promotes satiety, just to name a few. Good sources of fat include avocado, olive oil, coconut oil, coconut milk, full-fat organic dairy products, butter (especially grass-fed butter), eggs, quality meats, nuts, and nut butters. Any man-made fat (ie, “partially hydrogenated anything-oil”) should be avoided, as should high-in-omega-6 plant-based oils (cottonseed, canola, soybean, vegetable, safflower, sunflower, etc) because they promote inflammation in the body.
*I’ve chosen to use “Fiber” instead of “carb” here because the former invokes thoughts of fruits, vegetables, and whole grains, whereas the latter is often assumed to mean processed grains (pasta, bread, snack bars, candy, etc) – which lead to a bigger spike in blood sugar and are not as nutrient-dense.
Let’s look at a few examples. An apple isn’t a bad afternoon snack, but it’s not very balanced in terms of protein, fat, and fiber. Sugars, albeit naturally occurring ones, make up the majority of calories in the apple. If you add some cheese slices** or slather some nut butter on those apple slices, you’ve now got a snack with protein, fat and fiber. The protein and fat in the cheese or nut butter will slow down the absorption of the natural sugars, leaving you feeling satisfied longer and with a more stable blood sugar level.
**Just for the record: We’re talking “real” cheese here, like a nice cheddar or jarlsberg or gouda or pepperjack (can you tell I love cheese?!); no overly-processed “reduced fat” cheeses or individually-wrapped Kraft singles (which technically don’t even contain enough real cheese to be labeled as such; this is why the label says “prepared cheese product”!)
Another example: Oatmeal is touted as a great heart-healthy breakfast, but like the apple example above, it’s primarily carbs with minimal protein/fat. Many people choose to wash it down with a glass of fruit juice, which may seem healthy, but juice presents a very high sugar load to the blood stream (yes, even the “all natural, no sugar added” varieties). Let’s give this oatmeal breakfast a make-over! If you’re eating a flavored oatmeal (ie, most likely harboring much more added sugar than your body is comfortable with), switch to plain rolled or steel-cut oats. Ditch the fruit juice – and toss some berries or other fruit (fiber!) of choice onto your plain oatmeal along with chopped nuts, ground flaxseed or chia seed, and cinnamon. Top it off with some real butter. Now… how about adding a hard-boiled egg (or two) for some extra protein and healthy fat? This breakfast will be considerably more filling — no mid-morning energy crash here! — and will keep blood sugar stable, providing you with a constant supply of energy until lunch time and fewer cravings for junk food.
Here’s your homework assignment: Think of the meals and snacks you’re currently eating and identify the protein, fat, and fiber component. If something is missing, what are some ways you can make it more balanced and “metabolically efficient”?
Anne-Marie Alderson is an ITCA-certified Triathlon Coach and certified Metabolic Efficiency Training Specialist. Metabolic Efficiency workshops will be listed on the Steel City Endurance Events Page when they are scheduled. One-on-one or small group consults can be scheduled upon request.