Why low carbs diets work

If you are an average joe (sedentary, family man, etc.) and you tried to follow a low carb diet (hopefully based on the evolutionary eating guidelines), you’ve probably had success. As with many other people who have had success on such a diet, you probably started to believe that most – if not all – carbs are bad for you. Because you are busy, the nutritional research you have done has been limited. You still quickly found out about words like insulin, insulin resistance and blood sugar. The information you read stated that carbohydrates disrupt insulin and blood sugar and lead to insulin resistance. Insulin resistance is the reason you gained weight. Here is a new perspective on the subject.

While everything I just wrote is true, it’s important to understand how it is applied in practice. Yesterday, I wrote a quick review of my stance on carbohydrates [link here]. The comments of my readers, as well as the whole theme of the post inspired today’s post, so I hope I answer all of my readers’ questions in this article. In a nutshell, today, I will argue about how low carb diets seem to work for most of the average joes, and how they are not always adequate for the most active-joes. Basically, it’s a post about the often forgotten part of the low carb diet equation : just because it can work, it does not mean that it is optimal for everyone.

At a very simplified level, the body of a healthy person runs mostly on fats. The body uses both dietary and stored body fat as a source of energy to do most daily tasks. As long as the intensity of the task you are doing is low, it’s likely that you are burning fat (body fat and dietary fat). Obviously, the average joe’s life is based on low intensity tasks : he has an office job, he sits most of the day, his hobby is watching TV or playing video games with his kids, and his idea of exercise is walking [click here to read my post about walking and its benefits].

In other words, all through his day, his muscles (most likely slow-twitch muscles since the intensity of his muscular contractions is low) produce ATP energy by fat (primarily) and carbs (if needed) oxydation. However, because the level of intensity is so low, he rarely needs to oxyde carbohydrates to create ATP, and that’s because our body prefers fat as a source of energy. ATP is the energy that our body uses to make the muscular contraction happen or stop (don’t worry, I have a post about this coming up that should make everything clear). Put simply, every time you move (be it typing at the computer like I am doing at the moment, or standing up from a seated position), some muscles contract and some stop contracting. All of this is possible mostly because of ATP energy (as well as tissues).

Now, the average joe rarely get physically fatigued due to his level of exercise (he does not exercise outside of his daily tasks). This is due to the fact that fat is highly present (either in dietary or body fat form) in his body which, in turn, means that it can produce ATP energy all through the day. This means that he rarely uses carbohydrates (we run out of glycogen really quickly) for fuel. Another way to put it is that the average joe’s level of stored glycogen is likely to be high. This means that the need to replenish it is very low. Thus why low carb diets work for the average joe.

So, why does he not use glycogen as much as the most active-joe? Good question.

The more intense the activity is, the more glycogen you use. The average joe rarely ever does intense activities and this is why he rarely use glycogen as a way to fuel his activities. His body uses the best fuel available for the given task which is, as we have seen, ATP produced from fat oxydation.

The most active-joe’s life is a mix of low intensity (walking, job, etc.) and high intensity (working out, running, sprinting, etc). activities. This means that at times his body will most likely prefer to use fat as fuel and, at other times, carbohydrates as fuel. Now, I know a few of my readers will point out that you can train without eating carbohydrates, and it’s true. You can also train without eating at all, too. Or, you could train with eating nothing else than a single type of food, too. You can do a lot of things, but it does not mean that it is optimal!

One thing is sure, it’s very hard to train an athlete without having him eat at least a little bit of carbohydrates (my choice : sweet potatoes). If he is a strength athlete, his strength gain will probably be limited if he does not eat any carbs. He needs the carbs to make muscular contractions happen. Endurance athletes really need carbohydrates. Basically, runners drink sugar during their runs because we run out of glycogen really quickly.

It’s important to understand that I am not advocating a high carbohydrates diet here. However, what I am saying is that a diet where the amount of carbohydrates is based on the amount of glycogen you use is the way to go. Average joes have success on low carb diets because of their low glycogen use, not because carbohydrates are evil. Athletes or active people can afford to eat more carbohydrates, also because of their glycogen use (which is higher than the average joe’s).

This leads us to a question that I will let you answer :

Is it better to lower the amount of carbohydrates you eat to match your use of glycogen, or is it better to up the amount of glycogen you use to match up your [moderate] carbohydrate intake?