This article is the third installment in our nutrition series.
In part one we talked about the basics of nutrition including what exactly micro and macro nutrients are and what role they serve in the body.
In part two we covered how the body turns food into cellular fuel.
Now that we have an understanding of how the body converts glucose into fuel (ATP), let’s zoom out a bit to see how the body regulates our blood sugar throughout the day to ensure we always have the appropriate amount of energy.
Blood sugar simply refers to the amount of free floating glucose within our bloodstream. When we eat carbohydrate rich foods, the starches within the food are broken down in our stomachs and then absorbed into our bloodstream via our small intestines. Within the pancreas exists beta cells, which are constantly checking the bloodstream to determine if the amount of glucose is either too high or too low. Your can think of these cells like a thermostat in a room. Your body has a set temperature (glucose level) that it likes and these beta cells are there to ensure that homeostasis is achieved.
After you eat a meal, your body is flooded with glucose. Free floating glucose is of no benefit to your body. In fact, prolonged exposure to high blood sugar levels is known as hyperglycemia and results in a host of pathological disorders including blood vessel and nerve damage. To make use of the glucose in the bloodstream, the beta cells in the pancreas secrete a hormone called insulin. Insulin facilitates the transfer of glucose from the bloodstream into the actual cell.
You can think of insulin as the great matchmaker within the body. Pairing lonely glucose molecules with hungry cells. If you eat a particularly large meal and ingest more glucose than your body has demand for, insulin will store the excess glucose as glycogen within either skeletal muscle cells or the liver. If your body’s glycogen levels are at capacity, excess glucose is converted to fatty acids and stored as triglycerides within adipose tissues.
Insulin is not just a matchmaker for glucose, but also helps with protein synthesis (pairing amino acids together) and, as mentioned above, storing fatty acids within adipose tissue.
As your body goes about busily moving glucose from the blood to within your cell walls, your blood sugar level begins to drop. Your beta cells determine there is less glucose and slow their production of insulin. This process repeats itself every time you eat a meal.
Now that we understand how the body handles glucose in the bloodstream, we need to shift our attention to the mechanisms at play when our blood sugar levels are too low. Beta cells within the pancreas have a sister cell called alpha cells which constantly check to see if our blood sugar levels are too low. Generally speaking, this occurs between meals, while we’re asleep and during strenuous exercise. In response to low blood sugar, your pancreas releases another hormone called glucagon.
Glucagon is the opposite of a matchmaker. It’s more like a demolition expert. It travels throughout the body looking for stored energy and releases it into the bloodstream. The first place it looks is within our liver. Breaking down glycogen into it's usable form of glucose. If the liver is tapped, it starts breaking down stored fat (triglycerides) into fatty acids for energy. I like to imagine glucagon as a crazy Bond villain, standing at the base of a dam with a set of explosives - blowing it up and releasing the water (stored energy) into the bloodstream. Or, as a mafioso, trying to win influence in a poor neighborhood by handing out loaves of bread to hungry citizens.
For the record, glucagon is no bad guy and plays a vital role in maintaining balanced blood sugar levels. I just happen to find personification memorable. If you’re more of visual learning, check out the below diagram.
First, this shits cool. Having a deeper understanding of your biochemistry is never wasted time. Additionally, understanding how the body manages energy stores will allow you to have a better understanding when it comes to topics such as the glycemic index, insulin insensitivity and type 2 diabetes.
We often joke in the gym that back squats will cure type 2 diabetes. Or, you should look to cut out refined sugars from your diet otherwise you'll get type 2 diabetes. These comments are not gospel, they're more like coaching cues: short, precise tactics to fix an issue, but, by their very nature, do not expose the whole issue.
Like all chronic diseases, the development of type 2 diabetes is a complex process that involves many factors. What we're describing below is a typical path not certainly not the only way.
Type 2 diabetes is a chronic disease were your body no longer effectively responds to insulin. This typically occurs when an individual makes many poor decisions regarding their health - i.e. they do not exercise and eat predominantly processed foods. This individual is now in a constant energy surplus. As we learned above, when we consume more food than our body knows what to do with, insulin stores glucose and fatty acids as triglycerides (stored fat).
As we continue to gain weight, the increase buildup of fat creates an additional barrier around our cell membranes. When insulin goes to work trying to match glucose in the bloodstream with hungry cells, it is unable to do so as effectively. The result is a negative feedback cycle where excess blood glucose is stored as fat, but our cells don't get the energy they need. So, we feel tired and hungry. This exacerbates the problem of not wanting to work out and feeling like we need to eat again. The process continues on and on.
Side note: Skinny people can get type 2 diabetes as well. The mechanisms described above are the same, but these individuals hold their fat around their internal organs instead of under their skin.
So, the coaching cue that back squats cure diabetes is short hand for saying, if you exercise and keep a healthy body weight you'll help protect yourself from diabetes. And the cue to cut out refined sugars is short hand for saying eat whole foods. Whole foods are nutrient dense and filled with fiber. Processed foods are typically the exact opposite. Eating whole foods will help you eat the appropriate amount of calories and avoid a constant energy surplus.
Stay tuned for our next post where we'll cover pre and post workout nutrition!