Low-carb diets are the most popular type of diet today. However, in spite of their popularity, not very many people actually know how they work or why they are still a very controversial method of weight loss.
Some people religiously believe that carbs are bad for us, whereas others are seeing good results without cutting them out. Even professional researchers and nutritionists have different opinions on carbs.
So here I’m going to give you a good understanding about how low-carb diets actually work, and why some people wouldn’t recommend them.
How it works
On a low-carb diet, it's possible to lose 2kg within a week. Maybe you’ve experienced losing 5kg within 2 months after you stopped eating bread. This quick result is why these diets are so popular. However, it's biologically impossible to burn 2kg of fat within such a short time.
What are we losing then? The answer is: water.
In our body, 1g of carbs (stored as glycogen) is attached to 3g of water. This is due to the structure of the molecules, and it means that if you lose 1g of carbs, you lose 4g in total.
1g carbs + 3g water = 4g
When you lose 2kg in total, it means you’ve lost about 500g of carbs, and 1500g of water in total (although the actual calculation is a little more complicated). As you might have heard, you can die after not drinking water for 3 days - drastically reducing your water content is that stressful on the body.
In addition to this dehydration stress, if you keep eating less carbs you are basically forcing your body into survival mode. This is what people call “ketosis”, which is when your body uses fat rather than carbs as an energy source, and is the goal of a ketogenic diet.
The problem with this system is that your body's ability to handle carbs deteriorates. As a result, when you start eating a normal amount of carbs again, you’ll have a blood sugar spike.
Repetitive blood sugar spikes over a period of time can cause insulin-resistance which leads to type 2 diabetes, and causes the body to store more fat in the long-term.
The process of getting back to normal after stressing your body like this can be very tricky because you have to think about your blood sugar and insulin levels. The more extreme the diet becomes, the more caution you need to take. Even bodybuilders sometimes miscalculate the process and some end up needing to go to the hospital when their bodies cannot adjust to the change.
Therefore, it is very important that you understand how low-carb diets work and how to get back to your normal diet smoothly before you start one.
Things aren’t as straight forward as they sound.
I mentioned above that ketogenic diets aim to “switch” the metabolic system to burning fats rather than carbs. However, the reality is a little more complicated.
People say "cut out carbs for 5 days, and your body switches the metabolic system to start using fat more”, but this theory doesn't make sense when you think about what's actually going on in your body when you burn fat.
Long story short, using fat as an energy source is super inefficient, and it is the last resort for your body. When you look at the chemical reactions, our bodies use 13 times more oxygen to convert fat into other forms, when compared to carbs. (Technically speaking, the calculation is not this simple.)
Switching your whole metabolic system means you would have to breathe in 13 times as much oxygen as you regularly do... that would be very stressful, and also unrealistic. It would be like working full-time at McDonalds and switching your scooter to a big V8 engine car, saying “I can afford it. I just need to work harder!” It's just not realistic.
In reality your body would prefer using a more efficient source of energy than fat when carbs are not available: muscles.
The body can break your muscles down to create energy (this is called catabolism). As a result of catabolism, your body reduces muscle mass, which also reduces your metabolism because you have less muscles that burn energy. You want to avoid this because reduced metabolism means that your body could start storing more fat.
This means that if you are on a low-carb diet then you are not getting a sufficient amount of carbs, and doing exercise means you are breaking muscles to build muscles. This is counterproductive!
It’s not sustainable
The reason why low-carb diets are not recommended by some people is very simple. Low-carbs diets are not a sustainable method of weight loss for most of us, and are not suitable for our lifestyle today. Let me explain:
Anyone can start a low-carb diet, but in reality you have to catch up with your family and friends and of course there’s regular pizza, noodles, dumplings, and bread. We also have Christmas, New Year’s, weddings, your birthday, your friends’ birthdays, and many other events.
Maybe you can sustain a low-carb diet if you persist. Maybe, in the future, society and our lifestyles might adjust to even more varieties of diets as they did to vegetarian and vegan diets. However, low-carb diets haven’t gained widespread recognition like that, at least at this stage.
If you don’t have a supportive environment when you change your diet, it’s harder to keep it up. This is why so many people end up giving up after a few weeks. If your diet inflicts limitations on the food you eat and the people you hang out with, can we still call it a healthy lifestyle..?
It’s not clear if we really need to cut out carbs
Another reason why I think some people don’t recommend low-carb diets is because there is conflicting evidence as to the effectiveness and health benefits of low-carb diets. Yes, there’s evidence that such diets will help you lose weight. On the other hand, a growing number of research suggests that they can cause cardiovascular issues in the long run.
The science hasn’t proven the necessity of cutting out carbs from our diet for human health. So, let’s leave existing evidence and think about this question:
Are low-carb diets really necessary for losing weight?
Looking at any culture, many traditional dishes have carbs as their main dish. We, humans, have been eating carbs for hundreds of thousands of years. That’s how we developed as humans. Obesity has only become an issue in the past 20 or 30 years; that can’t have been caused by carbs.
Think of it in terms of the body’s digestive mechanism; Saliva contains an enzyme specifically made to digest carbs. From the first moment you put something in your mouth, your body starts digesting it to take it into the bloodstream. If carbs weren’t important, why would the body have such a dedicated system for digesting them?
Our brain's primary source of energy carbs. Our muscles’ primary source of energy is carbs. Humans evolved over millions of years to rely on carbs. Then, all of sudden, you hear people saying “stop eating carbs.” Why do they need to make it sound like it’s the only solution?
It is important to discuss if low-carb diets are good or bad, but you should not forget that carbs are necessary in our life. Aren’t there other things that you can do for your weight loss or health before going extremes like that?
Carbs are not bad
Carbs are necessary for our bodies. Carbs can be only bad when you eat too many poor-quality carbs such as sweets, white bread, or white rice.
There are other things that you can change or improve before cutting carbs. If you are sitting down for most of the day, stand up and move more often before trying to cut carbs. If you can’t stop eating too much, have a food diary to see if the quality of your diet could be the reason that you cannot control your appetite before trying to cut carbs. If you have a stressful life that makes you binge eat, find solutions to remove the cause of your stress and have a relaxing weekend before trying to cut carbs.
Too much is as bad as too little. Everything needs to be in moderation.
It’s your choice
So, this was my explanation and opinions, backed up by evidence that I trust, about low-carb diets. But the choice is yours. You make the decisions for yourself. The latest science today will be wrong in 10 years. You need to know what works the best with YOU, and you should keep looking for that until you feel confident about what you decide to do.