If we only have between five and seven grams of sugar circulating in our bodies at any given time, what happens when we ingest sugar or carbs?
When we eat sugar, it will raise our blood sugar – glucose, more specifically. Carbohydrates contain sugars and starches. When you eat those, the blood sugar goes up. What’s remarkable is the lack of understanding, even in the medical world, of how little sugar there is in the blood. Consider, for example, an apple has 20 grams of total carbohydrates. This is four times as much sugar as is in your bloodstream at any given moment. If you don’t have this huge insulin response to keep the sugar down, one apple could double your blood sugar easily. In someone with diabetes, this is not okay. If you want to optimize your blood sugar or glucose, don’t have so much blood sugar-raising food, like carbohydrates. Eating carbs raises blood sugar.
What happens in the pancreas?
The perspective has changed for me. I was taught (and most doctors are taught) that it’s normal for a rise in blood sugar after eating a meal and it’s normal for insulin to be secreted from the pancreas to lower the blood glucose and to help get the glucose into the cells. I’ve shifted in my thinking now, that while it may be normal, meaning it’s what happens in most people, it’s not optimal. The blood glucose is regulated in a very tight control. If it goes up a little bit, the body doesn’t like that; it sends out insulin to lower the blood glucose and it puts it in the cells. This insulin spike or insulin response to lower the blood glucose is a pro fat-storing, pro-inflammatory response. Any time you eat even an apple, even if you don’t have diabetes, it raises that blood glucose, which raises the insulin to keep the glucose down and then insulin sends a signal to the liver to make fat and to store fat. It’s not only driving you toward diabetes, it’s driving fat storage and weight gain.
Are carbs and sugar the same thing?
Yes. That’s important to realize in the teaching out on the internet. You have to be precise about the language if you’re going to say ‘glucose’ and ‘fructose’. You’re going to find people making it overly complicated. My method of teaching, which I’ve done for over 20 years now at Duke University, is to try and keep things really simple. If there’s a bit of glucose in an apple, I’m going to say count that as a carbohydrate, as a glucose-raising substance.
Starches, which include potatoes, pasta, and rice, are just glucose molecules all connected. Our body digests them into glucose and that’s why when you eat potatoes, pasta, rice, or bread, your blood glucose goes up like when eating an apple. If you look at “sugar-free” products out there, they may be sugar-free, but they have a lot of starch in them. They’re not carbohydrate-free. My simple way of teaching and thinking in my own mind is to put all the carbs together, because a subset or a portion of the carb will be glucose, which will be raising the blood glucose. You don’t want to have anything to raise your blood glucose much, because then your body sends out insulin to keep the blood glucose down.
What happens when we stop eating sugar and carbs?
The remarkable thing is that the body makes its own glucose. It makes its own sugar without you eating anything. We’ve talked about these reality shows where people go out into the wilderness and don’t really eat anything and they start losing their body fat fast – well, they also maintain a blood glucose level without eating anything. Your body can make glucose, fructose, and the other sugars you need without you actually eating sugar. Of course I don’t want you to go without eating food like on these reality shows, but your body makes plenty of glucose and fructose and other sugars, like ribose from the proteins and fats that you eat. Your body is going to have a certain blood sugar level and if you throw in extra sugar, your blood sugar goes up, which triggers insulin to go up to lower the blood sugar – we call that the roller coaster of glucose when you’re consuming carbohydrates. Your body will find its own way to make the blood glucose steady if you don’t eat carbohydrates.
What happens the moment one completely stops eating carbs? How long does it take for blood sugar and glucose levels to drop?
There is a range of time course for different people, depending on their underlying insulin resistance and metabolism. For most people, this shift happens in just a day or two. If you burn a couple thousand calories of energy a day and you stop consuming carbohydrates in food and drinks, your body needs 2,000 calories for the next day. We only store about 1,000 or 2,000 glycogen calories, which is the sugar storage, so it only takes a day or two for your body to shift over to fat burning. If you have diabetes or you have a lot of fat to lose, it may take longer; that’s a tougher metabolism. But for most people it’s just a day or two. You stop eating sugars and your body figures out how to burn its own fat. It happens pretty fast.
If those are the immediate effects, what happens after a week and then after a month?
The insulin response to keep the blood glucose down starts healing; it starts getting better. If you’re so insulin resistant or you have diabetes where you might have elevated insulin levels all day long, these start coming down. If you’re otherwise normal and healthy, the insulin reduction will happen almost immediately and that means you don’t get the pro-inflammatory effects of insulin or the growth effects of insulin. We’re learning now that it can even shorten lifespan. In animal studies with worms and rats, animals lived longer when their insulin levels were lower. The lower the insulin, the better – in terms of how you feel, through less inflammation, and even in how long you’ll live. Of course, that’s not worked out in humans yet. It takes a long time to do a study of a human lifespan, because we generally live so long, but the biomarkers are there to suggest that you want to keep the insulin level down. One way to do this is to keep the food that raises the glucose and insulin to a minimum in our diet.
Does the length of time without carbs affect our fat burning efficiency?
I think so. Within the clinical knowledge that I have from treating people with illness, there’s a wide range of how fast things change. Sometimes I have to reduce insulin by 50% on the first day when someone starts a diet like this. If they stop eating carbs and they’re taking insulin, I have to change the medications immediately. For other people, maybe those preparing for a marathon race, it can take a few months to optimize fat burning to the standard of an athlete. For most people, however, it’s a matter of days to a couple of weeks where you start getting the benefits of fat burning.
The studies on people who have done this for years are just being done now. We’re learning more and more about what happens to people. It’s looking really good as we study a keto lifestyle longer.
Check out the full video here.