In this video, Dr. John McDougall says that after one of his high starch/low fat meals, blood sugar can rise as high as 150, and he says that it’s fine- not a problem.

He doesn’t think that such temporary spikes in blood sugar are the essence of diabetes. He says that they are normal and supposed to happen. After citing 150 as acceptable, he said that spikes of 200 or higher may need "medical attention" temporarily until enough weight loss occurs to correct it. He says that the cause of Type 2 diabetes is excess weight, and that he has a 100% cure rate because his patients, on his starch-based diet, lose weight. Then, he goes on to say that in a short while, as conditions improve within your body, your blood sugar hardly rises at all after meals. Hmm. But, isn’t he contradicting himself? If first he defends blood sugar spikes as being normal and physiological, as well as good and necessary, why does he then brag about them largely going away on his program?  Are they good or are they bad? He needs to make up his mind.

I have never done post-prandial blood sugar testing on myself, so I don’t know how high my blood sugar goes after eating. I eat pretty large meals, and I assume that it rises substantially. But again, I’m just guessing. I checked online, and the figure most often cited as an acceptable spike is 140.

So, I don’t know how high mine goes, but it seems to me that more important than how high the spike goes is the rapidity at which it comes back down. And that’s because good health is all about maintaining homeostasis. When you consume food, you are nourishing yourself, but you are also disturbing the steady state within your body. So, your body gets to work to undo the disturbance. So, it sends the glucose to the liver and muscles where it’s converted into glycogen and stored there, thereby lowering the blood sugar back to its steady state. The quicker and more efficiently it does that, the healthier you are. Right?

And that’s why I would give more importance to the speed at which my body undoes the spike than the height of the spike because the height of the spike may be largely a function of how much I eat. In other words, if I were testing it, and I wanted to ensure that I get a good result, I could “cheat” just by not eating as much. But, that really wouldn't mean anything.

So, the bottom line is that both are important, but of the two, the duration of the spike and the speed at which it resolves is more important than how high it goes. 

And consider the people who eat very low-carb meals. Dr. McDougall pointed out that even they experience some rise in their blood sugar after meals. And, even those who follow the Carnivore diet and eat only animal foods, which have zero carbs, assuming they don’t consume milk which has lactose, even they experience some rise in blood sugar. How? Apparently, gluconeogenesis happens very fast. Most of the amino acids that comprise proteins can be converted into glucose. The body clips off the amino group, which gets converted into urea and excreted, and the rest gets converted into glucose. Then, the glycerol in fats is very easily converted into glucose. Glycerol is basically half a glucose. The body just puts two of them together to make a glucose. So, it’s easy to see how blood sugar can rise even when you eat nothing but protein and fat. For multiple reasons, I think it’s very bad to do that, and one of them is that it cranks up all the gluconeogenic mechanisms in your body to the max.  On such a diet, your body becomes a sugar-making machine. I’ve read about the “dawn effect” which refers to the rise in blood sugar that occurs early in the morning, shortly before rising. So, you’re lying in bed sound asleep, and your blood sugar starts rising, and the keto diet can make that worse, again, because you’ve honed your body to churn out sugar.

But, I don’t think Dr. McDougall is right to celebrate potatoes, corn, and rice, the way he does. I think nuts and beans are more valuable foods when it comes to diabetes management and prevention. Being higher in protein, they support muscle mass better, and maintaining good muscle mass is key because muscles are like sieves for blood sugar. It’s muscles that take sugar out of the blood and convert it into glycogen which is harmless. Glycogen does not react with proteins and cause glycation the way glucose does. And don’t get me wrong: I do eat potatoes because they are a whole natural food. But, I’m not a fanatic about it. If I had to choose between keeping nuts or potatoes in my diet- if I couldn’t have both- I would ditch the potatoes and keep the nuts. Of course, Dr. McDougall would do the opposite.