As you will know, eating carbs on the keto diet is a big no. That’s because carbohydrate restriction induces the metabolic state of ketosis. As we have previously discussed, this leads to a host of associated health benefits[1][2].
However, do you really know how many carbs you’re eating?
It’s easy enough to avoid obvious carbs like bread and pasta. But this becomes more of a challenge for hidden carbs from added sugar. So let’s explore the sources of these extra carbs, and what you can do to avoid them.
Table of contents
Introduction to hidden carbs on the keto diet
The keto diet is a low carbohydrate diet, centred on inducing the metabolic state of ketosis.
By primarily consuming dietary proteins and fats, the body quickly depletes stored glycogen. This promotes the release of fatty acids, which are subsequently used to synthesise ketone bodies[1][2].
Now that’s a long way of saying carb restriction is required on keto. Typically, this means restricting carbs to less than 50g per day. Importantly, this is net carbs, not total carbs.
Total carbs vs net carbs
An important concept to familiarise yourself with is net vs total carbs. This is key to determine whether a food is actually bad for your keto diet.
Total carbohydrates are ALL the carbs in a food, including fibre. Net carbs on the other hand are the result of the amount of total carbs, minus the amount of fibre.
This is because fibre has a minimal impact on blood glucose levels, meaning it doesn’t impact ketosis[3].
For example, let’s say 100g of food A contains 15g of carbs. On first look, this looks like a food to avoid on the keto diet. However, if it has 13.4g of fibre, the net carbs are only 1.6g!
Overall, the impact on blood sugar will be minimal, making food A keto-friendly. Looking out for net carbs is therefore more important than total carbs.
What are the different types of carbohydrates?
But what exactly are carbs and are they all the same?
Carbohydrates are 1 of 3 macronutrients (the others being proteins and fats), composed of carbon, hydrogen and oxygen. Carbs are technically a non-essential macronutrient and serve as a primary source of energy[4].
Broadly, there are 2 different categories of carbohydrates; 1) Simple and 2) complex carbohydrates.
Simple carbohydrates
As the name implies, simple carbohydrates are well…simple. These carbohydrates consist of one or two sugars (monosaccharaides or disaccharides), combined in a simple chemical structure[4].
Common examples include fructose, lactose, maltose, sucrose and glucose. You can find these carbs in sugary foods like candy and syrups[4].
Simple carbs are very easily digested, causing rapid spikes in blood glucose. Spikes in blood sugar subsequently lead to increased insulin secretion, which is detrimental to the keto diet. As a result, simple carbs have high glycemic indices and should be completely avoided on the keto diet[4].
Complex carbohydrates
Complex carbs are a bit more diverse. They consist of 3 or more sugars bonded in a complex structure. Due to the complexity, they take longer to digest and therefore result in a more gradual increase in blood sugar. This also means they tend to have a lower glycemic index[4][5].
Common examples include amylose, cellulose and dextrin, which can be found in foods like broccoli, spinach, whole grains and brown rice.
Complex carbs can be further sub-categorised into starches and fibre.
Starches have a complex chemical structure and contain a large number of glucose molecules. Good examples of starches include potatoes, pasta and wheat[4].
Fibre on the other hand is split between soluble and insoluble.
Insoluble fibre cannot be digested but adds bulk to bowel movements, and keeps the gut healthy. In contrast, soluble fibre can be digested and is associated with a number of health benefits[4][6].
Simple carbs are most likely to sneak into your diet
So why does this all matter? Well, by understanding the different types of carbs, you’ll be able to determine which sources are responsible for the additional carbs in your diet.
For example, on the keto diet, complex carbs such as vegetables are commonly consumed. This is because they contain close to zero sugars and a high proportion of fibre.
Other complex carbs, e.g. potatoes and brown rice, can easily be avoided as they are more obvious sources of carbs. Nothing hidden about these carbs!
Simple carbs on the other hand, are sometimes included in seemingly keto-friendly foods, making them more difficult to spot. With that said, let’s explore the common sources of hidden carbohydrates and how to avoid them.
Common food sources of hidden carbs
Condiments and sauces
Condiments and sauces often contain added sugar, making them sources of hidden carbs.
One of the trickiest sources of hidden carbs are condiments and sauces. People often neglect to pay attention to the nutritional profile of condiments, as they are viewed as a fairly minor part of their diet. However, they’re often packed with sugar making them a poor choice for the keto diet.
Common culprits include barbecue sauce (33.2g sugar per 100g), teriyaki sauce (14.1g sugar per 100g) and ketchup (21.8g sugar per 100g)[7][8][9]. (These are general figures but individual brands will vary in nutritional composition.)
Servings of high-sugar sauces can easily add up, pushing your net carbs over the edge.
Salad dressings
Salad dressings can contain high amounts of sugars and should be carefully selected.
It’s common for salad dressings to be overlooked as they come with, well…salad. If there is one food that’s definitely low in carbs it’s a salad. Or so you would think.
Dressings like French dressing contain almost 20g of sugar per 100g. Similarly, balsamic vinegar can contain over 15g of sugar per 100g (depending on the brand)[10][11].
Adding these dressings can quickly make a healthy keto salad less keto-friendly. Do this a couple of times a day and before you know it, you can find yourself over your carb threshold.
To avoid this, opt instead for fat-based dressings such as olive oil.
Marinades and seasoning
I have to admit, this one has caught us out more than once.
You would think meat was the one food that would be completely free of carbs. While meat, such as steak and lamb, on its own is carb-free, marinades and seasonings are often not.
Some popular marinades and seasonings actually contain quite a lot of sugar. When you’re cooking for yourself, it’s easier to use marinades and seasonings that are lower in carbs. However, when you’re out and about its not always clear which meats are appropriate.
Sticking to dry rubs is probably a good bet and likely to contain significantly fewer carbs.
Nuts
If there is one snack that is consistently recommended on keto, its nuts. Nuts are great sources of healthy fats and can indeed be a great snack on keto. However, if you’ve ever eaten salted nuts, you’ll know they are extremely palatable[12].
This can quickly escalate and before long you’ve eaten the whole bag. What’s worse, you’ll realise that you actually consumed a whole bunch of carbs.
Not all nuts are created equal though, as some contain significantly more carbohydrates than others.
Higher carb nuts include the following (per 100g);
Fruits
Fruit is generally healthy and has been associated with risk reductions in a number of chronic health diseases.
As you may know however, fruit can contain high amounts of sugar[16].
Over-consumption of fruit is a common mistake for keto beginners. They know to cut out carbs such as bread and pasta, but see fruit as a healthy option. Unfortunately, some fruits contain high amounts of sugar, even when taking into account their fibre content.
Like nuts, not all fruits are created equal. Some fruits such as mango contain high amounts of sugar, and should be avoided on the keto diet.
Fruits containing high amounts of sugar that should be avoided include (values per 100g);
Vegetables and legumes
Now I know what you’re thinking…vegetables are healthy and have got to be keto-friendly? Well, for the most part you would be correct.
Vegetables are low carb and rich in essential vitamins and minerals[20].
However, some vegetables and legumes such as sweet potatoes and beans, actually contain quite a high number of carbs. These are different from the simple sugars found in fruits. Instead, they are composed of complex carbohydrates, including high amounts of fibre[21].
However, the net carbs of these foods is high, meaning they should be avoided on keto.
Other vegetables such as carrots, contain higher proportions of sugars and should therefore be consumed in moderation[22].
Smoothies and shakes
Smoothies can be a great way to consume healthy vegetables and get the vitamins and minerals you need.
As mentioned, certain fruits and vegetables contain higher quantities of sugar and should be avoided. Hidden carbs often sneak into ‘green’ smoothies as the colour suggests they contain mostly leafy vegetables, such as kale and spinach.
These smoothies can often be topped with sugar or fruit, so pay attention to the nutritional values.
You also need to be careful with protein shakes. While protein shakes can be good for a post-workout snack, some brands are loaded with sugar. Stick to options high in branched chain amino acids, but low in carbs.
Dairy
Some dairy sources commonly contain hidden carbs
Dairy can be a great source of protein and fat on the keto diet. Foods such as milk and cheese are rich in minerals such as calcium, which is essential for maintaining strong muscles and bones[23].
Dairy products naturally contain the sugar lactose. Lactose is normally present in small quantities, constituting a fraction of the total nutritional composition. Ok dairy, so far so good[24].
Some dairy products however, such as yoghurts, may contain a higher number of carbs. This is particularly common in sweetened milks and yoghurts[25].
How to avoid hidden carbs entering your diet?
Many foods that are generally considered ‘healthy’ often contain a higher than expected number of carbs (many of which come from sugar). By understanding the pitfalls, you’re more likely to successfully adhere to your keto diet.
We’ve now covered the the types of foods that contain ‘hidden carbs.’ The next question is, how can you best avoid them?
Read the nutritional information
This might seem like a no brainer but it’s often overlooked. Diligently reading the nutritional information is one of the easiest ways to ensure you’re not accidently eating extra carbs.
Make a habit of reading the nutritional information with a specific focus on carbs, sugars and fibre. By understanding the difference between total carbs and net carbs, you’ll be able to decide if a food is acceptable for your diet.
This may seem overwhelming at first, but you’ll quickly get used to it. Once it becomes second nature, you’ll have a much better idea of which foods to avoid.
Get a fitness app / nutrition tracker
If reading all the nutritional information feels a bit too much, there are always fitness apps. There are many fitness apps available which have dedicated nutrition trackers. Some even enable you to scan food barcodes, which can automatically update your nutrition tracker.
This way you can easily set a carb-budget and plan out your daily meals. Apps are also a great way to prevent overeating, and ensure you’re getting the right balance of protein and fat.
One of the most popular trackers on the market is myfitnesspal. Why not check it out?
Avoid processed foods
Processed foods are generally unhealthy and long-term consumption is associated with poorer overall health[26].
It’s important to emphasise that ‘processed foods’ can be used as an umbrella term for many different types of foods. For example, there are processed meats such as hot dogs and cured ham. These foods should be avoided as they can contain added sugars, and are generally associated with poorer health[26].
On the other hand you have packaged foods which can include ‘assorted salads.’ They’re generally best avoided as they frequently contain added carbohydrates. Alternatively, you can invest slightly more time reading the nutritional information to determine whether they’re compatible with your diet.
Prepare and cook your own food
Preparing you own food is a great way to avoid hidden carbs.
By buying the raw ingredients and cooking your own meals, you can be assured of what you’re eating. This is a great way to control for carbohydrates and can also help you build a good routine. A good routine is essential for long-term consistency.
Cooking your meals at home should constitute the majority of your diet. Eating out on occasion is perfectly acceptable on keto, but recognise you’ll have less control over what you’re eating.
Utilise sugar-free alternatives
As mentioned earlier, many foods have hidden added sugars that could impact your keto diet. However, the flip side is that many of these products have sugar-free alternatives. Ketchup for example has a reduced sugar version. These sugar-free products can be a great way to use sauces and marinades without impacting your diet.
Similarly, when it comes to smoothies, you can replace the sweetness from high-sugar fruits with natural sweeteners, such as stevia and xylitol. These sweeteners have zero (or significantly reduced) sugar, making them a keto-friendly alternative to sugar.
You can learn more about natural sweeteners and sugar alcohols in these articles.
Concluding remarks
Avoiding carbs can be tricky, especially when you first start out on keto. However, by following the above recommendations, you’ll quickly be able to determine which foods likely have hidden carbs.
Remember, one of the best ways to avoid hidden carbs is through the nutritional information. This can save you a lot of hassle in the long run and is definitely worth the time investment.
