I notice that many of the low-carb and no-carb advocates, including doctors who advocate those diets, like to talk about glycation reactions in which the reaction of glucose with proteins causes damage. It’s also associated with aging. It makes sense to them that the way to avoid this is to avoid carbohydrate as much as possible, even completely. However, it is not sound thinking, in my opinion, and I’ll tell you why.

You know that your body has two states of being: wakefulness and sleep. You know that it switches back and forth between these two states on a circadian basis. When you’re healthy, the “switch” that controls the daily transitions is very efficient, and you don’t spend much time in a transitory state. You go quickly into sleep from wakefullness, and you quickly reach full awakeness and mobility when you come out of sleep. It’s nice when the whole process is very efficient, isn’t it?

Well, there’s a similar thing the occurs metabolicailly in which the body has two states: eating and fasting. When the body is in an eating state, it is burning sugar, glucose for energy; not exclusively, but primarily. But, when the body is in a fasting state, it burns primarily ketones from fat, and it burns much less sugar.

The body stores very little carbohydrate. There is glycogen, which is “animal starch” stored in the muscles and in the liver, but it gets used up very quickly once a person starts fasting. From that point on, if the body were to continue burning sugar, the body would have to break down proteins to make it, and when fasting, your body does all it can to limit protein loss. It has to break down proteins some in order to provide amino acids for vital functions, both structural and enzymatic. However, it doesn’t want to break down proteins for fuel, just to burn. That would be like burning the furniture to stay warm. So, since the body stores caloric energy mostly in the form of fat, that’s what it seeks to burn during a fast in order to spare bodily proteins.

So, in the normal operation of the human body, it goes into ketosis when it’s fasting, and it also happen in various states of sickness. But, it’s not supposed to happen under normal eating conditions. In other words, you’re not supposed to go through life in a perpetual state of ketosis. In ketosis, you have bad breath; you have a bad taste in your mouth; you get dehydrated. You’re not supposed to go through life like that.

And the body is determined not to go through life like that. As I have emphasized before, human break milk is the sweetest milk of any mammal. So, what happens within the body of a nursing mother who is eating a carnivore diet? Her body undergoes massive gluconeogenesis, and the result is that her milk is just as sweet as that of a carb-eating mother. Milk composition is a highly regulated thing. As long as her diet has enough calories, and is sufficient otherwise, she will churn out that sugar for the baby. The difference in milk composition is quite small despite massive differences in macronutrient consumption, and it’s quite amazing.

So basically, the body cannot be talked into or forced into the low-carb mantra. It wants what it wants, and it will move heaven and earth to get it. So, the body of the nursing mother will churn out sugar, through its own metabolic conversions, so that the baby gets what it needs.  But, what about the baby? What if the mother weans the baby to a no-carb diet, where it goes from sweet milk to non-sweet meat, fish, and eggs and nothing else?  Then, the body of the baby will do the same thing and start churning out sugar via gluconeogenesis.

So, very low carb and no carb diets turn the body into a sugar making machine. And the sugar that it makes from glucogenic amino acids and from the glycerol portion of fats is just as likely to undergo glycation reactions with proteins as the sugar from plants. But, the unrefined plants at least contain antioxidants and polyphenols and other things that help limit the damage.

Being in a state of carbohydrate deprivation and ketosis while eating is quite stressful for the body, and it results in a raising of the cortisol level, which is a stress hormone. And one of the effects of cortisol is to increase blood sugar. Now, people vary a lot in this regard, but in some people, the blood sugar can shoot up very high as a result of this mechanism.

When it comes to blood sugar, what you want is normality. You don’t want your blood sugar to be abnormally high or abnormally low. When you eat a very low or no carb diet, you are teaching your body to be carbohydrate intolerant. So, let’s say that you are eating that way, but then you stop eating that way, and resume eating a normal amount of carbyhydrate- which you consider a binge. You won’t tolerate it well. You’ll incur a greater spike in blood sugar than the person who is used to eating carbohydrates on a regular basis.  

No one is going to avoid glycaton reactions completely. For instance, they test the blood for glycated hemoglobin, and normally, it’s a little over 5%. So, that means that 5% of the hemoglobin in the blood is damaged. But, it never goes to zero. And it would be alarming if it did. You would probably be dead if it did. If hemoglobin A1C gets too low (below 4.5) it is associated with increased all-cause mortality and cancer.


So, does that mean that there is something beneficial about having 5% of the hemoglobin in the blood damaged from glycation? I rather doubt it. It’s the conditions that led to the A1C getting that low that are harmful.

The right way to proceed, in my opinion, is not to adopt the extreme measure of avoiding dietary carbohydrates but rather to keep your carbohydrates unrefined, since whole foods affect the body very differently than refined foods. And that includes something as simple as eating a whole apple rather than drinking apple juice. It’s far better to eat the whole apple.

Then, the second thing is to control for calories. It’s one thing to limit carb consumption by radically skewing the balance of protein, fats, and carbs, but it’s another thing to limit carbs by limiting calories overall. We know beyond a shadow of a doubt that caloric reduction is the most proven life extension technique. It’s been proven in animals large and small. Of course, it’s never been tested similarly on people because it would mean controlling their calories for their whole lives, and it isn’t practical to do that for 80 or more years, and it would be inhumane. But, they have done experiments in which they controlled for calories in people for short periods and compared markers for aging, such as telomere length, and saw impressive results.

So, I say eat whole unrefined foods and be attentive to calories. I don’t say to live life with a calculator every time you put something in your mouth because that is no fun. What you need is a general plan to limit calories. When you make fresh fruits and vegetables a big part of your diet, it is going to automatically reduce calories because these foods are so high in water and fiber which have no calories.  Eating a lot of fresh fruits and vegetables is the most painless way to eat low-cal because you still get to eat. You get to eat a lot.

But, as far as the balance between proteins, fats, and carbohydrates, rather than trying to limit carbs within the group, or limit fats within the group, the one you should really want to limit is protein. Remember that most of the calories you eat are for fuel. It’s stuff you burn. And you don’t want to burn protein. You want to get enough protein to meet your structural, enzymatic, and functional needs (to make things like neurotransmitters) but you don’t want to start burning the furniture. Hydrocarbons are for burning, and that means carbs and fats.

And keep in mind that I do NOT advocate ultra-low-fat diets, such as Pritikin, McDougall or Esselstyn. There is absolutely nothing wrong with eating healthy fats.  But, you have to remember that fats are more calorically dense, and since the most proven thing is to control for calories, you have to factor that in when you’re eating high-fat foods, such as nuts.

I suppose in the end it comes down to one thing: balance. But, avoiding carbohydrates completely as a dietary tactic is extreme. It is extremely extreme.