I know there are about a billion articles on this topic already floating around out there. But I learned something REALLY COOL in Human Nutrition this week that completely revolutionized the way I think about this, and I wanted to share with you.
So, after you eat a meal, your body breaks down all the components into little chunks it can use. Proteins become amino acids, lipids become fatty acids, and carbs become glucose. Glucose is the basic molecule from which all our energy comes. Turning glucose into energy is a pretty complex process that I’ve now learned about in three different classes, so you’d think I’d have it completely down.
You would be wrong. It’s really complicated.
But that’s not what I want to tell you about (thank your lucky stars).
You’ve finished eating and digesting, and all that lovely glucose from your food is now floating around in your blood. The problem is that it doesn’t do any good in your blood. It needs to get into your cells, so that your cells can then do the work of converting it to energy so that you can move and breathe and use your iPhone. There are a variety of ways that this happens – one of the ways involves a protein called GLUT4.
GLUT4 hangs out inside the cell until it’s needed. It knows it’s needed when insulin levels spike – this is pretty much the entire goal of insulin (to help glucose get inside cells and out of the blood). Insulin goes up when blood glucose levels go up. So insulin tells GLUT4 to get busy transporting the glucose, and the GLUT4 protein moves up to the cell membrane to start pumping the glucose in. Then the cell can do its job and turn it into energy.
All good, right? Right.
Unless you’re diabetic. If you’re diabetic, your cells are what’s referred to as insulin resistant. Some other diseases can cause this problem too. Just as you’d think, it means that your cells are resistant to the signals coming from insulin, so the GLUT4 proteins don’t ever move to the cell membrane and the glucose doesn’t get pumped in, and you don’t make energy*.
Not good, right?
Lucky for us though, there’s a backup system. GLUT4 proteins can also get the message to get busy from calcium.
No, drinking milk won’t help. That will just go to your bloodstream and make your blood glucose even higher.
The calcium is actually already stored in your muscles. Just chillin. The key is exercising – the movement of muscles causes that stored calcium to release, and it then triggers GLUT4s and starts the process through a back door, of sorts.
THIS IS WHY DOCTORS ARE ALWAYS TELLING DIABETES PATIENTS TO EXERCISE. Even just an easy walk, right after a meal, will make those GLUT4 proteins move and start pumping sugar (aka glucose) out of your blood and into your cells, despite the fact that the insulin in your blood isn’t doing the job.
This is also why it’s important for diabetics to eat right after exercise – because the GLUT4 proteins are working and busily pumping away, your blood sugar is going to drop quickly. Additionally, you want to take advantage of the fact that the pumps are open – if you wait too long to eat, they’ll close again and the problem will start all over.
This is also why even non-diabetic people get hungry after exercising. Our cells are clearing all the glucose out of our blood, which means we need to intake more or we’ll start losing energy.
Isn’t that mind-blowingly cool? I have diabetic family members and so I’ve heard doctors give that advice before, but I never understood why it works. I think that if doctors told patients things like this, so that they understand exactly how the advice will make them healthier, rather than a generic, “just exercise after eating” with no explanation, patients would follow that advice a lot more!
So, that whole “walking off a meal” thing isn’t BS after all. It really can work!
When do you usually exercise – before or after a meal? Do you think doctors sharing this kind of info would help patients make healthier choices?
*There are of course other proteins to help do this, so it’s not like you’ll never make energy and you’ll die. Plus I’m oversimplifying a bit.