Is Marketing Slang Messing With Your Low-Carb Diet?

My #macnutritionuni course is really making me think and accept that some of my old views need slightly adjusting and bringing up to date! This week The Fundamentals of Carbs – Biochemistry and Metabolism was the topic, now I love carbs, even when dieting for shows, I am a Carb King.  But impact, non-impact, net and effective carbs and are new to me and I had to pause, go back and go over that bit a number of times before it started to sink in.  Then it made me think about low carb foods, especially protein bars, and can we really eat them guilt free?
Carbohydrates are not essential was the first bomb shell – NOOOOOOOO – I love carbs, however they are our primary energy source as the brain and CNS (Central Nervous System) utilise glucose as the primary fuel and require a continual supply. Phew – no Keto for me then!
With the pandemic “Open Gob Syndrome” – also know as obesity and a sedentary lifestyle – hitting global proportions, low-carb diets are here to stay. There is no question that they can be very effective for fat loss when done properly. But low-carb diets aren’t easy for those who are used to eating a lot of carbohydrates. Restricting the amount of carbohydrates that you eat in order to get results is tough and certainly isn’t fun. It’s not unusual for this currently starving bodybuilder to be found gazing longingly at a piece of cake (yep window licking!! or drooling), so I do have empathy with the low-carb dieter.


Impact carbs, non-impact carbs, effective carbs and net carbs are the latest buzz words in the weight loss industry, but are people getting more than they bargained for with foods and supplements that are based on effective, net, non-impact and impact carbs?
It sounds like a dream come true eating non-impact carbs and still get the results of a low-carb diet, but are these designer-foods/protein bars slowing or even stopping any progress?


A carbohydrate is a nutrient that is used by your body for energy. It contains 4 kilocalories of energy per gram (kilocalorie is the formal name for calorie).
When you eat carbohydrates, your body breaks them down into glucose which is transported through the blood to be either stored in the liver and/or used by muscles.
When carbs are broken down into glucose and enter the bloodstream (often referred to as blood sugar) the body recognises this and releases the hormone insulin, which signals to your body to absorb the glucose. When your body doesn’t require the glucose for energy, insulin signals the body to store the sugars for later use as glycogen store in the muscles and, once these stores are full, as fat. This conversion can happen rapidly or slowly depending on the type of carbohydrate food eaten. By controlling insulin secretion, you can effectively improve your body’s ability to mobilise fat from fat cells. Once mobilised from the fat cells, they are more readily burned for energy, i.e. you lose fat. This is the basic premise that most low-carb diets are based on.
Carbs can be broken down further into the subcategories; simple and complex carbohydrates.
The difference between a simple and complex carb is in how quickly it is digested and absorbed. This is called the Glycemic Index. The further up the scale a food is (simple), the faster the carbohydrate is broken down and the faster the rise of blood sugar is. The lower on the scale (complex), the slower the rise is.


Simple carbohydrates, also known as ‘simple sugars’, are found in lots of foods like:
  • Sweets
  • Fizzy drinks/sodas
  • Artificial syrups
  • Sugars
  • White rice, white bread and white pasta
  • Potatoes (technically a complex carb, but act more like a simple carb in the body)
  • Pastries and Desserts

Eating lots of simple carbohydrates, especially in the form of added sugars, raises blood sugar levels very quickly causing excess fat storage.


Sources of Complex Carbohydrates:
  • Oats (old-fashioned or Steel Cut)
  • Yams
  • Brown rice
  • Sweet potatoes
  • 100% whole wheat bread
  • 100% whole wheat pasta
  • Beans and lentils
  • Quinoa
  • Couscous

Complex carbohydrate foods provide vitamins, minerals, and fibre that are important to the health of an individual. The majority of carbohydrates should come from complex carbohydrates (starches) and naturally occurring sugars, rather than processed or refined sugars, which do not have the vitamins, minerals, and fibre found in complex and natural carbohydrates.


The name that’s often given to simple carbohydrates that cause a rise in blood sugar levels is “impact carbs” as they have a higher impact on blood sugar levels than carbohydrates that have less of an impact on blood sugar levels. That’s it!
Eating lots of impact carbs, especially in the form of added sugars, raises blood sugar levels very quickly causing excess fat storage.


Non-Impact carbs, in a nutshell, are carbs that have very little effect on blood sugar levels when they are eaten. Since they don’t have an impact on blood sugar levels, they are technically “allowed” on most low-carb diets.
Examples of non-impact carbs that you’ll see in low-carb foods and supplements include fibre, sorbitol, maltitol, and glycerol.
Fibre is completely indigestible by the body and passes through unused but it is essential as part of a healthy diet.
Sorbitol, maltitol and glycerol are what are known as “sugar alcohols.” They are digested by the body but have little to no effect on blood sugar levels and are in most protein bars.


The Effective Carb is the opposite of the Non-Impact Carb. They are carbs that will have an effect on blood sugar levels. In most low-carb diets, the idea is to place a limit on Effective Carbs to keep blood sugar and therefore insulin levels under control.


The Net Carb count is basically the same as the Effective Carb count. It’s the total number of carbs in the food minus the non-impact carbs. These terms can really be used interchangeably, which can be a source of confusion in consumers.
Net Carbs = Total Carbs – Dietary Fibre – Sugar Alcohol
For example, if a food contains 30 grams of carbs and 10 of those carbs are fibre and 5 sugar alcohols, the food contains 15 grams of net carbs. It’s basically what’s left over after you subtract everything else.
The term “Net Carb” was coined by supplement makers after glycerol (the non-impact sugar alcohol discussed above) was reclassified by the FDA as a carbohydrate. Previously, it had not been classified as either a carb or a fat and supplement makers were able to use it as a sweetener without adding to the carbohydrate count of a protein bar.
When this reclassification took place, the carb counts of low-carb protein bars increased dramatically! The term “Net Carb” is a result of manufacturers wishing to keep their carb counts down while still using glycerol in the manufacturing process.
  • Non-impact carbs are very effective at reducing the insulin response you get from eating foods made with them. This means insulin levels will stay more even throughout the day, which will definitely improve the body’s ability to burn fat.

  • Non-impact carbs help low-carb dieters stick to their diets. There is no denying that sometimes you just want to eat a protein bar. By eating a low-carb bar, you get the enjoyment of the confectionary while still keeping your insulin levels under control.

  • Low-Carb foods are actually being used by people who aren’t on strict low-carb diets but who just want to lower their carb intake. Non-impact carbs are very effective for this purpose.


  • While non-impact carbs don’t affect blood sugar levels, they still contain calories (except fibre, which is not digestible). A person who eats a lot of non-impact, carb-containing foods is still getting all the calories of an equivalent amount of regular carbohydrates! This fact is never highlighted in advertising for non-impact carb foods. Total caloric intake still matters on low-carb diets. If your body is getting too many calories, it won’t need to burn body fat.

  • If you eat large amounts (or in some people, even small amounts) of sugar alcohols, you could experience digestive issues and diarrhoea. Sugar alcohols are not normally found in large quantities in natural foods and the body can have a hard time digesting them. What the body has trouble digesting, it tends to get rid of as quickly as possible.

  • The EFSA and FDA (European and USA legislation Register) have not formally defined the terms “Low-Carb,” “Non-Impact Carbs” and “Net Carbs” as it has done with terms relating to fat content in food. Meaning many foods that are not particularly low-carb can get away with labelling themselves low-carb. As always, reading the nutritional information on the package and noting serving sizes is your best protection.


As ever there is not a yes or no answer – you can look at things from both sides and draw your own conclusions.
It looks like we can have our cake and eat it.  If that is part of a healthy, well balanced energy controlled diet plan. However are we falling for another marketing ploy from the large Manufactures?
Processed foods are what got us into the obesity epidemic that we’re in today. Is substituting one type of processed and manufactured food for another type of processed and manufactured food, albeit a “healthier” one, the right way forward?  My preference is to use non processed naturally healthy food sources that are naturally low carb. However, I am partial to a few protein bars on occasion that do definitely contain those “non-impact carbs”.  They can certainly be useful on an occasional basis, but I don’t believe it’s wise to rely on them for a significant portion of your food intake. I suspect you could easily find yourself not losing weight or