Do carbs really make you gain weight?

Disclaimer: Please note that this article is research based and some of the views and findings do not conform with the CSN Diet.

It’s the dirty word of dieting: carbs.

Pretty much everyone agrees. Cutting carbs is the way to go if you need to lose weight. Whether you just slow down or cut them out completely doesn’t matter, but the carbs have to go.

But consider this: what if everyone is wrong? 

What are carbs, exactly?

Carbohydrates are one of the basic food groups, the other being proteins, fats, vitamins, minerals, dietary fibre and water. 

All of these nutrients work together to help us remain healthy by performing the following functions in our bodies:


Builds, repairs and maintains healthy body tissues.


Provides energy, prevents heat loss in extreme cold weather and protects organs against shock. They make up part of our cells and transport fat-soluble vitamins A, D, E and K.


There are many kinds of vitamins, and they are responsible for different tasks in the body, such as maintaining healthy skin and hair, building bones and releasing and using energy from food.


Responsible for regulating body functions such as fluid balance, muscle contraction and transmission of nerve impulses.

Dietary fibre

Stabilises blood sugar, promotes gastrointestinal health and prevents constipation.


Regulation of body temperature, production of body fluids, transportation of nutrients and removal of waste products. 


A major source of energy for the body.

Carbs, protein and fats are macronutrients, and the three main ways in which the body obtains energy. The body needs large amounts of macronutrients to function properly.

Your body can’t produce its own macronutrients, and has to obtain it from the food you eat.

At chemical level, carbohydrates contain carbon, hydrogen and oxygen.

Why did we start disliking carbs?

It all started in 1861 with an obese undertaker named William Banting. Tired of being fat, he seeked help from his doctor, who devised a low-carb, high-fat eating plan for him.

In less than a year, Banting saw about 20kg melt away, and his life improved drastically. In his own words, he was “on a tramway of happiness”.

He was so happy, in fact, that he wrote and published a little booklet on his weight-loss journey, called A Letter On Corpulence. It sold 50 000 copies in two years.

By 1866 banting was the way to go in Europe. Since then, different versions of this lifestyle made their appearance, such as the Atkins diet and keto, still popular to this day.

Of course these diets are popular with good reason, with studies confirming plenty of benefits a low-carb diet brings you. These include:

  • Simple and effective weight loss.
  • Helps to get rid of harmful belly fat, eventually reducing your risk of diabetes and heart disease.
  • Increases “good” HDL cholesterol and improves “bad” LDL cholesterol levels.
  • Reduces blood sugar and insulin levels.
  • Lowers blood pressure.
  • Can help to reduce seizures in epilepsy patients.

With incredible health benefits as well as the potential to get rid of those bulges that bother us, it’s no wonder that low-carb diets became immensely popular. It also followed naturally that carbs became the bad guy.

Many people believe that carbs are unhealthy and fattening. How true is this?

Good carbs vs bad carbs

We have learned to associate carbs with obesity, diabetes and metabolic syndrome, but the truth is that not all carbs were created equal.

Carbs can be divided into three types: fibre, starches and sugars. Fibre and starches are complex carbs, and sugars are simple carbs.

The difference between the two, simply put, is that complex carbs are the body’s main source of energy. It helps to fuel our nervous system, muscles and organs.

Simple carbs send immediate bursts of energy into the bloodstream. They are digested quickly, and often offer your body little nutritional value. 

These are the type of carbs that are responsible for the earlier mentioned health problems. 

However, not all simple carbs are bad. Fruit and dairy contain simple carbs, but they can’t be compared with simple carbs like cookies and cakes. Fruit contains fibre and other nutrients that are beneficial to you.

Dairy contains healthy nutrients such as calcium, protein and sometimes probiotics. Processed carbs are a different story, as they often contain refined sugar and lack the nutrients your body needs.

Examples of healthy carbs

Brown rice



Potatoes and sweet potatoes









Examples of unhealthy carbs

White bread

White rice

Pizza dough








What happens to your body when you cut out carbs?

A diet that consists of very little carbs triggers your body into nutritional ketosis. This means that, when your body doesn’t have enough fuel to run on, the liver starts breaking down fat to produce ketones to keep you going.

In order for this to happen, your carb consumption needs to be very low – less than 10% of your total macronutrient intake. This is about 20-50g of carbs a day.

Now you will start to lose weight. In the beginning it will be mostly water weight, and this will come right back when you start eating carbs again. 

Ketosis kicks in after two to three weeks, and many dieters report rapid weight loss.

This almost sounds too good to be true. While it is in fact true, it’s certainly not fun and games. Many experts warn against cutting out whole food groups, with good reason. Here’s what could go wrong:

  • Sometimes called the keto-flu, you could develop symptoms like weakness, fatigue, dizziness and headaches. In more serious cases stomach ache, nausea and vomiting can occur.
  • As your body tries to keep up your normal blood sugar levels, your brain might feel foggy and you will be very tired. You could also battle to sleep.
  • Since low-carb diets generally lack fibre, you could suffer from constipation and bloatedness.
  • Your body will release ketones through your breath as acetone, causing your breath to smell fruity or sweet.
  • Eating very little carbs can lower your blood sugar, which can help if you have diabetes. There is, however, a risk of hypoglycemia, which is when your blood sugar dips too low.
    Be careful with this eating plan if you do have diabetes. Check your sugar often and have a discussion with your GP.
  • The keto diet, for example, is not only low-carb, but also high-fat, but be careful with your fat intake as it could affect your heart health. Stick to healthy fats such as those found in avos, olives and nuts.
  • You might find yourself in a negative emotional state as a low-carb diet reduces the serotonin levels in your brain. Serotonin protects you from anxiety and depression.
  • Your liver has more work to do on a low-carb diet, as there will be more fat to process. If you have an existing liver condition, a low-carb diet might worsen it.
  • Ketosis could wreak havoc with your kidneys. It could cause kidney stones, gout flares and drastically up your chances to develop kidney disease.
Key takeaways so far

Low-carb diets are massively popular as an effective way to lose weight.
This has led to the common perception that carbs are the enemy – unhealthy and fattening.

The truth is that you get different types of carbs and not all of them are bad.
Simple carbs are unhealthy, fattening and offer no nutritional value.

Complex carbs are very healthy. They fuel our body with the energy we need and work together with other nutrients to keep us functioning optimally.

Do carbs really make you gain weight?

So we have determined that some carbs are unhealthy and fattening, while other carbs are actually pretty good for you. We also know that removing carbs from your diet causes ketosis, which leads to weight loss.

But what if you want to lose weight, but you don’t want to completely remove carbs from your diet? Because let’s be honest, a life without potatoes is just not an appealing prospect.

No carbs lead to ketosis, but do carbs actually lead to fat?

Some sources claim that simple carbs cause weight gain by increasing your blood sugar levels. 

These blood sugar spikes are said to trigger a strong insulin response, leading to increased glucose uptake and glycogen storage. The excess glycogen is converted into fat, leading to weight gain.

The above is debatable, with other sources claiming that it has been proven incorrect many times, but that this is ignored by promoters of the low-carb diet.

According to Dr Joshua Wolrich of the UK’s National Health Service, the above-mentioned fat storage caused by carbs are not only normal, but essential for a healthy body.

“Fat storage, fat breakdown…the whole thing is a constant state of flux,” he says.

“Glucose is the most important fuel source for the body. Due to the fact that we don’t eat every minute of the day, there are times when our blood sugar levels need boosting.”

“That’s when the previously stored glycogen gets broken down back into glucose.”

One thing is generally agreed upon by experts – weight gain is caused by calories, not carbs. 

Multiple studies have shown that having carbs in your diet will not cause you to pick up more weight than someone who doesn’t eat carbs. 

It is true that some carbs are calorie-dense, so moderation is advised. This is the case for pretty much all types of food. If you consume more calories than you burn, you will gain weight.

It does not matter if these calories come from carbs, or a different source.

Bottom line

Cutting carbs can be an effective way to lose weight, but it does come with risks as our bodies actually need carbs. But, it’s good to know that carbs are not the culprit when we gain weight – excess is.

The science behind all of this can be a tad confusing, but the important thing to understand is that you can have carbs, just don’t overdo it.



Hi, my name is Karien Nel and today I’m 37kg lighter than the day I started my weight loss journey with CSN Diet.

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