Understanding carbohydrates, a low carb diet and the ketogenic diet plan

With the rise in popularity of the ketogenic diet, low carb diet plans are a topic of hot dispute. They're only really desirable if you have a high to very-high sensitivity towards refined carbohydrates. A low carb diet is one of the three diets DNAFit recommends based on your DNA test results. The following article covers everything you need to know about carbohydrates, a genetic predisposition towards carb sensitivity, and a low carb diet vs. the ketogenic diet.

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What is a ketogenic diet?

A ketogenic diet plan suggests that only 5 – 10% of your daily calories come from unrefined carbohydrates. It’s a high-fat (65 – 70%), moderate protein (25 – 30%), low carbohydrate diet. The keto diet forces your body to burn fat instead of carbs for energy.

Is the ketogenic diet a healthy low carb diet?

The ketogenic diet may sound like a silver bullet for weight loss - but it’s actually extremely dangerous for your health. Following a ketogenic diet plan for extended periods of time can cause all sorts of health complications such as cardiovascular disease, metabolic disorders and serious dehydration.

Like any restrictive eating plan, the ketogenic diet quickly becomes difficult to maintain. Eating large amounts of fat like this can result in nausea, vomiting and digestive problems (from lack of fibre). While you may lose weight rapidly, you’ll gain it back as soon as you return to regular eating patterns. This is because the ketogenic diet “reprograms” your body’s ability to process carbs. When you eliminate an entire food group for a long period of time, your body doesn’t know what to do with these nutrients when you add them back in to your diet.

Now, let’s take a look at the healthier option: a low carb diet plan.

What is a low carb diet? 

A low carb diet plan suggests that 25 – 40% of your daily calories come from unrefined carbohydrates. As you can see this is in no way is a ketogenic plan and does not eliminate carbohydrates (which we don’t recommend). The emphasis, in a low carb diet, is on choosing the correct type of carbohydrates and controlling your portion sizes. 

The diagram below gives you an example of your plate composition on a low carb diet.

To understand why your body needs carbohydrates, let’s take a look at what they are and what they do.

What are carbohydrates (carbs)?

Carbohydrates are one of three macronutrients (the others are fats and protein). Carbs are the fibres, sugars and starches found in fruit and vegetables, grains and dairy products. Despite what you may have heard, carbs are a necessary part of your diet for optimal health.

Why are carbohydrates important?

Carbohydrates are important for two reasons: they provide us with energy and are our main source of fibre. Sufficient fiber intake is vital to maintain a healthy digestive system.

Carbs provide four calories of energy per gram. There are two types of carbohydrates: unrefined and refined.

What are unrefined carbohydrates?

Unrefined carbohydrates (or complex carbs) are unprocessed and still contain naturally occurring fibre. They take longer to break down, releasing energy at a slow, constant rate - causing a slower increase in blood sugar levels.

They’re almost always the better choice of carbs.

Examples of unrefined carbohydrates include:

  • Sweet potatoes
  • Kidney beans
  • Whole wheat bread
  • Grains (like brown rice, quinoa and buckwheat)

What are refined carbohydrates?

Refined carbohydrates (or simple carbs) are processed to a point where the majority, if not all, of the natural fibre is removed. As a result, refined carbs are metabolised and absorbed very quickly. It’s these that you’ll want to avoid.

Refined carbs cause a rapid rise in blood sugar - which is good if you’re about to do strenuous exercise, but not great if you’re sitting at the office or watching TV.

Examples of refined carbohydrates include:

  • Fruit juice
  • Sugar and sweets
  • Breakfast cereals
  • White bread

Unrefined and refined carbohydrates can be further subdivided into fibrous, starchy and sugary carbohydrates.

Fibrous carbohydrates

Fibrous carbohydrates should make up the bulk of your diet. These are found in fruits, vegetables, whole grains, and legumes, and are typically unrefined. Fibre is important for gut health. It also slows down the absorption of carbohydrates, preventing rapid spikes in blood sugar levels - this is a good thing.

Starchy carbohydrates

Starchy carbohydrates can be either refined or unrefined. This depends on the processing it went through and if whole ingredients were used. Try to choose the whole grain option when it comes to flour, breads, pasta, and so on, and only include them occasionally. Limit or avoid the processed version of these starches (white bread, white pasta, French fries and most junk foods), they can behave as sugar.

Sugary carbohydrates

Sugary carbohydrates are digested, absorbed and metabolised very quickly. They cause rapid spikes in glucose and insulin levels. These carbohydrates can be referred to as refined carbs. Refined carbs include added sugars (soft drinks, baked goods, chocolates and sweets), as well as honey (including natural honey), syrups and fruit juices. These should ideally be limited to 6-8% of your total calories or avoided entirely (depending on your carbohydrate sensitivity).

Not all unrefined and refined carbohydrates are made equal

Certain unrefined carbohydrates have the ability to behave as refined carbohydrates and vice versa. This is where the glycaemic index and glycaemic load come in. This further addresses the quality and quantity of carbohydrates the carbs you choose.

What is the glycaemic index score?

Glycaemic Index (GI) score refers to the carbohydrate quality (how quickly the carbohydrate is released into your bloodstream two to three hours after eating). The GI could be classed as either low, intermediate or high. The lower the GI, the slower the release of the carbohydrate and the greater the feeling of satiety (fullness). Low GI foods reduce cravings and provide better sustained energy levels.

  • Low GI carbohydrates are broken down slowly during digestion and release gradually into the bloodstream. They maintain blood sugar levels after eating. These are ideally unrefined and should make up majority of your carbohydrate intake. Low GI score: 0-55.

  • Intermediate GI carbohydrates are broken down moderately during digestion and release moderately into the bloodstream. They keep sugar levels moderately steady after eating. These can be included occasionally. Intermediate GI score: 56-69.

  • High GI carbohydrates are broken down rapidly during digestion and release quickly into the bloodstream. They cause rapid fluctuations in blood sugar levels after eating. They behave as refined carbohydrates and should be limited. Low GI score: 70-100.

What is the glycaemic load score?

Glycaemic Load (GL) score looks at the quality and quantity of carbs (the overall of effect of a carbohydrate serving on blood sugar levels). The GL describes the GI, as well as the serving size of a particular carbohydrate. 

GL is calculated by multiplying the GI by the amount of carbohydrate in grams provided by a serving, then dividing the total by 100. As with the GI, the higher the GL, the greater the elevation in blood sugar levels. GL would be considered high with GL of 20 or more, intermediate with GL of 11 – 19, and low with a GL less than or equal to 10. Unlike the GI the GL is cumulative and as a result, the maximum glycaemic load for the day should add up to a score of 70 – 80.

Why are some people more sensitive to carbohydrates than others?

Some people are genetically predisposed to being sensitive to carbohydrates. This means that their bodies don’t tolerate or process refined carbohydrates very well. Carbs impact your insulin responsiveness. Insulin is a peptide hormone which helps your body turn carbohydrates into energy. It’s also involved in fat storage. Insulin resistance (caused by high levels of insulin) can lead to weight gain, as well as an increased risk of developing type 2 diabetes.

So, what exactly should you be eating on a low carb diet plan? 

The majority of your carbohydrates should be unrefined and low GI. Focus on including fibrous carbohydrates daily, starchy carbohydrates occasionally and limit sugary carbohydrates. In other words, include plenty of fruits, vegetables, whole grains and legumes.

Your daily caloric intake will vary according to your age, weight, height, gender, physical activity level and weight loss goals. Fats should make up 35 – 40% of your daily calories and protein 20 – 25% of your calories. Try to stick to unsaturated fats (avocado, olives, nuts, seeds, fish, oils and nut butters), as well as choosing lean protein (chicken, fish, etc.) options where possible. Saturated fats (like coconut oil or butter) can lead to weight gain and other negative health effect when eaten in excess.

A healthy low carb diet sample menu

We’ve compiled a sample menu for a 1500 - 1800 kcal diet. If your health goal is to lose weight, this may need to be reduced slightly to around 1250 kcal per day.


Oat and Berry Smoothie

½ – 1 cup(s) oat bran with ½ cup blueberries and 125ml (1/2 cup) low fat Greek yoghurt blended together



1 medium, low GI fruit (apple / kiwi / plum)


Roasted Butternut and Chickpea Chicken Salad

¼ - ½ cup chickpeas with ¼ - ½ cup roasted butternut

60g (2oz) – 90g (3oz) baked chicken strips

2 cups salad greens (lettuce, tomato, cucumber, green pepper)

3 teaspoons olive oil as a dressing


Fruit and nuts

¼ cup dried fruit

60g (2oz) mixed nuts


Baked salmon with baby / new potatoes, broccoli and cauliflower

3 – 6 boiled medium baby potatoes

90g (3oz) – 100g (4oz) oven baked salmon

2 cups steamed broccoli and cauliflower

3 teaspoons olive oil drizzled over potatoes, broccoli and cauliflower


Healthy nutrition requires a balanced diet. That means nothing in excess (not even the good stuff). No matter how healthy blueberries or bananas are, for example, eating too many of them at the expense of other nutrients, will throw your body off balance and create health complications.

We recommend losing weight the healthy way. Not only is a balanced diet less restrictive (therefore easier to follow), it’s more sustainable - so you’ll enjoy long-term benefits long after you’ve lost those extra ten pounds.

Download our eBook, The Ultimate Guide to Healthy Weight Loss, for some easily-actionable tips from our fitness and nutrition experts. 

Download eBook

We're always here to help and guide you. If you have a question about health, fitness or DNA testing, send it to advice.centre@dnafit.com and our experts will help you find the answer.

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