Whenever I’m at a social event, and someone finds out that I “do fitness”, someone will inevitably come up to me, and tell me that they’re on a low–carb diet, as if they’re expecting my nod of approval. Maybe a pat on the back, and a smiley-face sticker. Maybe a letter to take home to their parents or spouse.
The truth is that low-carbohydrate diets aren’t inherently good, and they aren’t inherently bad. Just as with most things in nutrition, there’s no good or bad. There’s only correct application.
But there sure are A LOT of myths and misconceptions when it comes to low carbohydrate diets. In this article, we’ll do a little myth-busting, and clear those misconceptions.
Here are the myths that we’re going to bust (and by “we”, I really mean “I”):
- Carbs/insulin are the reason for weight gain
- People on low–carb diets have more aesthetic bodies
- Low carb diets keep blood sugar levels low
- If you don’t eat carbs, you burn fat
On top of that, we’ll also cover:
- When it makes sense to be on a low-carbohydrate diet
- When it makes sense to be on a high-carbohydrate diet
Myth #1: Carbs/insulin Are the Reason for Weight/Fat Gain
False! Or at least only partially true. It’s more like excess carbs are one of the reasons for weight/fat gain. And processed carbs are the reason for weight/fat gain.
After all, most of the world is on a high-carb diet. Asians eat a lot of rice. South Americans eat a lot of corn, and Europeans eat a lot of potatoes. All sources of carbs. And yet, do any of them have the same obesity rates as North Americans? Nope.
Because, again, carbs aren’t the problem. Excess carbs are the problem because of simply excess calories. Excess calories from any source will cause weight/fat gain. Carbs aren’t an exception.
When I say “processed” carbs, I mean carbs that you don’t really find in nature. Carbs that have been engineered to be addictive. You see, in nature, no food is addictive. However, in a laboratory, food chemists are actually hired to make food addictive. How? The perfect recipe for food addiction is: sweet + fatty + artificial flavours. An example would be ice cream, cookies, pastries, etc. Remember the first law of nutrition: if it tastes good, it’s bad for you 😉
In nature, if something is sweet, it’s not fatty as well. For example, fruits are sweet, but they have little to no fat content. And also, something that is fatty isn’t also sweet. For example, butter is fat, but it’s not sweet. Cheese is primarily composed of fat, but it’s not sweet. Cashews and almonds are fat, but they’re not sweet. But combine fat, sweet, and has artificial flavours, that’s a recipe for addiction.
It’s quite literally meant to hijack the part of the brain that’s responsible for pleasure, and make you crave more of it.
Likewise, insulin is not the cause of weight gain, either. How do we know? Because if insulin was the cause of weight gain, then lowering insulin should result in weight loss. So a group of researchers in this study from the journal of Diabetes, Obesity and Metabolism took overweight people, and put them on a low-calorie diet. They were divided into two groups: one group was just on a low calorie diet, and the second group was on the same diet, but they were also given the insulin-lowering drug diazoxide. The results: no difference in either weight loss or fat loss at the end of 8 weeks between the two groups.
Furthermore, there’s the glycemic index, which is a measurement of how quickly any given food raises blood sugar. It was theorized that the greater the rise in blood sugar, the greater the rise in insulin. So then, why not measure insulin directly? That’s why the lesser-known cousin of the glycemic index exists: the insulin index.
And you know the irony? Several low–carb foods are actually high on the insulin index. Things like milk, beef, and fish. So they don’t raise blood sugar much, but they do raise insulin.
People on Low–Carb Diets Have More Aesthetic Bodies
This myth comes to us from what we imagine our hunter-gatherer ancestors were like: lean, strong and muscular. But that’s just our imagination. Remember, there are modern-day hunter gatherers, who live a very close lifestyle to what people lived like 10,000 years ago or more.
One example of modern-day hunter-gatherers is the Kalahari tribe. Here’s what they look like. Another example is the Piraha tribe. Here’s what they look like. In either case, can any of them compare with the aesthetics of a modern-day athlete, or even gym-goer who directly trains for aesthetics? No.
Low Carb Diets Keep Blood Sugar Levels Low
This is a partial truth. This is the exact intention of low–carb diets, and a well-designed low–carb diet will indeed do that.
But if carbohydrate levels go too low, blood sugar can paradoxically rise. Why? Because in the absence of carbohydrates, the body starts to go through a process called “gluconeogenesis.” That’s when non-glucose sources are converted into glucose, and raise blood sugar anyway. Frequently, protein can be converted into glucose. Where does the body get that protein? Mostly from muscle.
After all, why is it that diabetics can wake up with abnormally high blood sugar levels if they haven’t eaten in the last 8-12 hours? Gluconeogenesis. Remember that word, and use it casually in conversation with your friends. You’ll look smart.
In non-diabetics, usually, blood sugar levels will rise if you eat less than about 50 grams of carbs per day. Oh, the irony. You eat low carbs so that blood sugar stays down, but if you go low enough, blood sugar actually goes up.
If You Don’t Eat Carbs, You’ll Burn Fat
Another partial truth. The logic for this one goes like this: you have 2 fuel sources that you burn to stay alive: sugar (AKA carbs, glucose) and fat. If you take away one fuel source, you’ll be left with only one other fuel source to burn. Take away carbs, and you’ll burn fat. This is all correct. Where it falls apart is when low–carb zealots don’t distinguish between dietary fat and body fat.
Your body wants to do the least amount of work possible to stay alive. So if you have fat readily stored in the liver from the meal you just ate, your body will burn that first. Tapping into body fat is a costly process from an energy perspective. It’s much harder for your body to burn body fat than dietary fat.
Usually, if you eat low carb, you’re going to raise the calories elsewhere: either from fat or from protein. In either case, your body will burn whatever is readily available from your previous meal.
To burn body fat, as opposed to dietary fat, you need a caloric deficit. In other words, if it takes you 2000 calories to maintain your weight, you need to drop your calories below 2000 to lose body fat. Whether the loss comes from dietary fat, or dietary carbohydrates is irrelevant. The fat lost will be identical.
I can hear you thinking now “but wait a minute, Igor. I’ve tried both low-fat, and low–carb, and I always lose more weight on a low–carb diet.” Yes, you lose more weight. But you don’t lose more fat. Since along with carbohydrates, you also store water, if you decrease your carbohydrate levels, you’ll also drop some water weight quickly. But that’s all it is: water weight. Not fat weight. Capisce? Ever wonder why it is that if you’ve been on a low carb diet for a week or longer, and then, after your very first carb-containing meal you gain a crazy amount of weight (we’re talking 4-7 pounds, after a single meal)? That’s because your body greedily starts storing those carbs. And along with the carbs comes the water. You can’t gain 4-7 pounds of fat in a matter of 1 day, but you sure can hold on to that much water.
So now that we’ve thoroughly dispelled four of the most common low–carb myths, I don’t want you to think that I’m favouring high-carb diets. I’m not. I’m favouring the right diet for the right person. As I said earlier in the article, “there’s no such thing as good or bad. There’s only correct application.“
So let’s discuss correct applications for both low–carb diets and high-carb diets.
When a Low–Carb Diet Makes Sense
The most obvious case when a low–carb diet makes sense is for someone who is either a diabetic, or has insulin resistance.
But again, not too low. Not low enough to cause blood sugar to rise paradoxically.
This person may need to eat as few as 15-25% of their total calories as carbs.
Carbohydrates have the largest impact on blood sugar (compared to fats and proteins), so less carbs means lower rises in blood sugar.
There is also some evidence that lower-carb diets may be beneficial for brain function. But as that is not my area of expertise, I won’t delve into this one in any more detail.
Low carbohydrate diets also make more sense for someone who is sedentary. Carbs are high-octane fuel to fuel high-intensity activity. If there is no high-intensity activity happening, fewer carbs are necessary. But this then begs the question: why are you sedentary??? You should exercise!
When a High-Carbohydrate Diet Makes Sense
High-carbohydrate diets make sense for people who are active, and do high-intensity activity. If you participate in most sports or you do regular strength training and cardio, you have a higher requirement for carbohydrates than someone who doesn’t.
How high is high? It may be as much as 70-75%, but that has to be assessed on a case-by-case basis. Most people who are not at either extreme (not diabetic, but not extremely active) would need somewhere between 40% and 65% of their daily calories as carbs.