Carbs Make You Fat! Or Do They??
October 16, 2023
Do carbs make you fat? This question has populated nutritional debates for a while now.
To get to the crux of the argument we first have to understand what ‘carbs’ are. Carbs, or carbohydrates, are sugar molecules and as one of the three main macronutrients, are the preferred energy source for the body.
Carbohydrates are broken down in the digestive system into their chemical form – glucose. Glucose is needed throughout the body for respiration, which provides energy for the majority of cells in the body to carry out their functions.
Three types of carbs
There are three main types of carbs – sugars, starches, and fibre. Sugars are referred to as simple or fast-acting carbs. These are either one or two sugar molecules (mono- or disaccharides respectively) which are rapidly digested by the body (1).
These can be both naturally occurring, such as in honey, fruit, and milk, or can be added sugars like refined sugar or syrups (1; 2).
Starches are considered complex carbohydrates (or polysaccharides) as they are made up of a large number of glucose molecules and take longer to digest.
Starchy vegetables (potatoes and lima beans), pulses, and grains are foods considered to be starch (2).
Finally, there is fibre. This is the indigestible part of plant foods – you cannot get fibre from animal products. Fibre tends to be found in whole fruit and vegetables and wholegrain starch options (1).
When looking at nutritional information if calorie counting, its important to pay attention to all three carb types. Not all carbs are created equal.
Some carb-rich foods are highly nutritious, while others just use up our calorie quota up quickly, and can be tasty but with minimal nutritional benefit (3).
Now, as mentioned previously, carbs are important as they are the preferred energy source for the body.
Dietary guidelines recommend people eat 45-65% of their daily calories from carbs (or 200-300grams per day). But the type of carb matters.
Watch out for processed carbs
With a plethora of foods available to us in the modern age, we need to be careful about the amount of processed and ultra-processed carbs that make up our diet.
Simple and refined sugars tend to be hyper palatable and very easy to overeat – meaning the calories add up very quickly (3).
Foods like cookies, crisps, sugary fizzy drinks and desserts all are high in refined sugars. Consuming these sorts of foods causes a large spike in blood sugar levels, but then triggers a big crash.
As they are only made up of few sugar molecules, they are broken down very quickly by the body. The issue with this is you are not satiated for very long, therefore feeling like you need more food soon after (3).
Whole grain carbs
One way to feel satisfied for longer is swapping simple carbs for complex carbs, especially ones with high fibre content.
Whole grain is a term thrown around within the food industry, but what does that actually mean? Oat, barley, and wheat are considered grains. Grains are made up of three parts: bran, germ, and endosperm. The bran is the outer hard shell of the grain, which contains the highest fibre content and B vitamins. The germ is the middle layer, which is packed with essential fatty acids and vitamin E. And finally, endosperm is the soft inner part which contains the starch.
‘Whole grain’ is essentially when the food product is made of all three elements: the entire grain. Refined grains contain only the inner starchy part, therefore miss out on many of the nutrients (and fibre) that the grain has to offer (2).
Foods with high fibre content help slow down the digestion process of carbohydrates consumed.
Fibre has two types: insoluble and soluble. Insoluble fibre helps to soften and bulk stool aiding in the regularity of bowel movements. This type of fibre is found in brans, edible seeds, vegetables, potato skins and wholegrain rice. Soluble fibre helps to reduce straining while passing stool, blunts blood glucose levels post food consumption and reduces LDL (“bad”) cholesterol in the blood (1).
The complexity of carbs
Some studies have found that consuming complex carbohydrates with a high fibre content releases glucose into the blood stream slower, meaning there is a gradual increase in blood sugar level over a longer period of time.
Not only does this help satiating the body for longer, but also prevents less excess carbohydrate from being stored as fat within the muscle or adipose (fatty) tissue around the body (1).
The glycaemic index can be used to track how certain carbs effect blood sugar levels – an important tool for those with blood sugar sensitivity such as hyperglycaemia and type 2 diabetes.
The scale is from 0-100, representing how rapidly blood sugar levels rise after consumption. A low glycaemic score is less than 55, where foods provide a gradual increase, like porridge, muesli, sweet potatoes, and peas.
A high glycaemic score is above 70, where there is a rapid rise after consumption, like sweets, white bread, and crisps. Excessive consumption of high glycaemic foods is associated with risk of obesity, heart disease and type 2 diabetes (1).
The body controls its blood sugar level via the pancreas, through the release of the hormone insulin. When blood sugar level increases, the pancreas is stimulated to produce insulin, which signals the body’s cells to absorb glucose for storage.
When blood sugar levels drop, the pancreas makes glucagon which stimulates the liver to release stored glucose. This occurs to keep the body in a state of homeostasis – in a balanced state.
Consistent consumption of high glycaemic foods, those with high levels of refined simple sugars, can cause insulin resistance which eventually leads to development of type 2 diabetes (1).
But this doesn’t mean diabetics need to avoid all carbs.
According to Diabetes UK, knowing the glycemic score of different foods and eating complex carbs with high fibre content can help a diabetic manage their symptoms (1). This is due to the slower release of glucose into the blood stream, slowed by long chains of sugar molecules needing to be broken down, which is further slowed by the having indigestible fibre passing through.
Using a continuous glucose monitor can aid this process too by seeing in real time the personal response to individual foods, enabling the user to make even more informed choices.
Alternatively, a diet high in refined sugars and simple carbs triggers consistent spikes in blood glucose, chronically releasing insulin, reducing its effectiveness.
This is why the type of carb you eat matters – especially fibre.
All things fibre
Fibre also has other benefits for the body other than slowing the breakdown of starches. The daily recommended intake for fibre is 30-35g+ per day.
Studies have seen populations in western societies consume less than half of the recommended amount, and its impact can be seen through more incidences of metabolic disorders prevalent in the western world compared to more rural communities (4; 5).
Dietary fibre has its biggest influence on the gut microbiota we all have existing in our large intestine and colon. Millions of bacteria take host in our digestive tract and help us break down the indigestible plant material. Our digestive enzymes cannot break down fibre molecules, therefore, pass through our body and are metabolised through fermentation by our gut microbiota into short-chain fatty acids (SCFAs).
Evidence is starting to show the impact these SCFAs have on our glucose and lipid (carb and fat) metabolism. The number of SCFAs is dependant of the type and amount of fibre consumed.
Certain SCFAs activate a receptor in the colon that works on the GLP-1 pathway, which interacts with the pancreas triggering insulin release and inhibits glucagon – essentially improving insulin sensitivity.
Other SCFAs interact with the liver for lipogenesis, significantly reducing circulating fatty acid concentrations, as well as increasing the activity of adipose tissue, which increases fat oxidation and energy expenditure (5).
The research for this is still in its early days, but there appears to be a clear link between increased consumption of dietary fibre and improved glucose and lipid metabolism, essentially helping reduce the risk of chronic metabolic disease development such as obesity, type 2 diabetes, and heart disease.
Brain health
Carbs, in all forms, are quite clearly important for all areas of the body. But this especially true for the brain.
The brain consumes roughly 20% of total energy of the body and mainly depends on glucose. This glucose delivery needs to be continuous and tightly regulated. Glucose acts not only as a fuel for our central nervous system, but also a signalling molecule.
Slight changes in blood sugar levels signal the brain, which will modulate food intake (through satiety signals) and trigger the pancreas to release insulin or glucagon to control blood sugar level to achieve homeostasis.
Both hypoglycaemia (low blood sugar) and hyperglycaemia (high blood sugar) can have detrimental effects on the brain, therefore, regulation of blood glucose and achieving homeostasis is essential to remain functioning and healthy (6).
This is why insulin resistant issues, such as type 2 diabetes, can be worrying. If the body doesn’t respond to the insulin signals and absorb glucose into the muscles and liver, then the body remains hyperglycaemic, which can be life threatening.
Having good insulin sensitivity is essential, which is why the type of carb matters – starchy carb choices with high dietary fibre!
Recent studies have looked at fructose impact on the brain. Fructose is glucose’s partner in sucrose (or sugar). Fructose consumption in recent years has hugely increased – now at 50-80g per day in developed countries.
Fructose is found naturally in fruit, which also contains fibre, but it’s also very prevalent in ultra processed foods like biscuits and fizzy sugary drinks, which DON’T contain fibre.
The increase in fructose in western diets is paralleled with the rise in obesity. Due to quick absorption into the blood stream, high fructose diets are related to weight gain and insulin resistance.
One issue with fructose is that it does not appear to send as powerful a satiety signal to the brain as glucose does, essentially not decreasing hunger sensation, and so potentially aiding overeating. Some rodent studies have also seen that high-fructose diets have triggered memory deficits and increased anxiety-related behaviours, but the link with humans is not yet clear (6).
Either way, it is clear that high fructose diets can promote overeating, which is the main driver to becoming overweight! It’s not the fructose itself though, it’s the influence on our behaviour.
Carbs’ influence on fat
Finally, there is the link between carb intake with triglycerides and cholesterol levels in the body.
Triglycerides, or lipids, are fats found in the blood taken in by the body from food. They can also be converted from excess carbs in the diet by the liver. They tend to be deposited in the adipose tissue around the body or in the muscles as a future energy source.
They subsist with cholesterol in lipoproteins in the blood. These lipoproteins are either low-density lipoproteins (LDL or “bad” cholesterol) or high-density lipoproteins (HDL or “good” cholesterol). Now cholesterol has many important functions within the body, including cell membrane construction, brain tissue and hormone synthesis.
However, elevated levels of triglycerides and cholesterol are highly associated with atherosclerosis (damage to blood vessels), heart attacks and strokes. This is due to the depositing of the smaller LDL particles into the damaged blood vessels and forming plaques; these plaques can then detach and form clots around the body causing severe health consequences (7; 8).
Elevated triglycerides are often a result of excessive carb intake due to the conversion to triglycerides in the liver. Elevated triglycerides can decrease the number of HDL particles in the blood. HDL particles tend to carry TGR and cholesterol back to the liver.
Therefore, the more LDL particles, due to carb conversion to triglycerides, the more likely triglycerides are deposited in fatty tissue around the body (8).
Now this may seem that carbs are the enemy here and that they do indeed make us fat. But this tends to only be true when our carb content is made up of mostly simple sugars from ultra-processed foods like cakes, chocolate, and excessive consumption of white pasta, rice and bread etc, and our calorie consumption is over that which our bodies need.
Studies have shown that a diet of simple sugars raised triglyceride levels. But when sugars are swapped to a diet high in starches, LDL cholesterol decreased and triglyceride levels remained the same (7). This suggests that a healthy diet of mostly complex carbs does not increase our levels of fat within the body and can actually help prevent it being deposited.
YourOneLife Opinion
Carbs are demonised in society. And this article brings up some very interesting points surrounding why they are.
Carbs high in refined sugars are easy to overeat on and spike our blood sugar levels. This excess will be converted to fat and stored in the working muscles or the fatty tissues around the body. In the literal sense, carbs can make you fatter. But the key point is when overall calories including from carbs are in excess.
Now long-chain starches have been shown to not spike our blood sugar levels due to the time it takes to break the carbs down, therefore having a slower impact on the blood sugar.
But even consuming long-chain starches in excess will increase fat stores. In fact, eating anything in excess will.
This is because the body is still focussed solely on survival – the way it was back when we were cavemen and didn’t know when we were getting our next meal. The body wants to store any excess food in case of times of hardship. The body is trying to help our future self.
But in the modern age, with supermarkets full of food and takeaways only a press of a button away, this can actually be a detriment. Therefore, if we want to lose weight, we need to be aware of how much food we need to consume.
Eating foods in excess is what makes us fat – not specifically carbs. Now there are definitely better foods to consume than sugar. But sugars are not the enemy either. Everything needs to be in moderation, and it’s so important that we enjoy what we eat. It’s not realistic to cut out all ultra-processed foods. We just need to make sure we’re not eating them in quantities harmful to our health.
At YourOneLife we support the 80/20 principle where if 80% of our calorie intake is from as nutrient-dense (and also tasty) food as possible, we can have whatever we fancy with the other 20%.
Nutrient-dense carbs are extremely important for the body, especially the brain, therefore, demonising them all and avoiding all carbs is not the answer.
Making sure the majority of carbs in your diet come from starches, wholegrain if possible, should be a consistent daily aim to help keep your body energised and functioning. There are some diets that steer away from carbs all together, such as keto, and people have found some success with this. The body adapts by converting fat into usable glucose for the body.
But the body still needs glucose and unprocessed carbs are a good source of essential vitamins and minerals.
Eating carbs is the best solution to avoid lack of energy – just make sure they’re not all refined carbs.
The biggest issue that makes us fat is eating more calories than we use – otherwise known as eating in a surplus.
Eating just an extra 120 calories a day can end up with us putting on stone over a year! It soon adds up.
Avoiding overeating, understanding yourself and your triggers, as well as bringing more awareness with what you eat is key to gaining control of your weight.
And here at YourOneLife, that’s what we do to support you. If you think you need this kind of help, head over to YourOneLife and check out our 1-2-1 services and self study programmes. Email claire@youronelife.co.uk or visit www.youronelife.co.uk
Claire x
Claire Jones is a multi-award-winning Sustainable Weight Loss Coach, Mentor, Therapist, Speaker and Author of the popular book “How To Eat Less”. She helps people learn how to confidently manage their weight well for life, after successfully managing her own weight for the last 12 years, following a 25 year yo-yo dieting battle.
With a career background of over 25 years spanning the NHS, HM Prison Service, and the UK Fire Service, she has seen first-hand what happens when people don’t look after their health, and has a natural desire to help and to serve those in need.
However, it was after overcoming decades of yo-yo dieting and learning how to look after her own health, that she found a particularly unique way to be of service.
She realised she had found an effective, unique and sustainable solution to the weight loss and regain cycles that so many go through, that cripples their confidence and holds them back from the lives they really want.
She is known for her relatable, down-to-earth manner and for helping her clients finally crack the code to their healthy weight and happiest selves.
With thanks to contributing author James Jones PT, BSc (Hons) Psych (1st)
References and Further Reading
1) Physiology, Carbohydrates – Holesh, J., E., et al. (2023).
2) Types of Carbohydrates – American Diabetes Association. (2023).
https://diabetes.org/healthy-living/recipes-nutrition/understanding-carbs/types-carbohydrates
3) Do carbs make you gain weight? Here’s what a dietitian has to say: Cutting carbs may be doing more harm than good – Rizzo, N. (2023).
4) The health benefits of dietary fibre – Barber, T. M., et al. (2020).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7589116/
5) Dietary fibre modulates the gut microbiota – Cronin, P., et al. (2021).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8153313/
6) Carbohydrates and the Brain: Roles and Impact – Fioramonti, X., and Penicaud, L. (2018).
https://www.intechopen.com/chapters/68362
7) Taming elevated triglycerides, insulin resistance, and syndrome X – McDougall, J. (2003).
8) Carbs and triglycerides: Their relationship and its ability to predict the presence of insulin resistance – Luks, H. J. (2021).
Find out how I can help you
Book your FREE 15 minute discovery call (online video or phone call) to find out how I can help you.
Related posts
- Published On: July 6, 2023|11 min read|
Intermittent Fasting for Weight Loss: Weighing up the Pros and Cons
What’s all the Fuss About with Intermittent Fasting for Weight Loss? Modern society has made life easier on many fronts. Cars to take us long distances, supermarkets provide an [...]
- Published On: April 10, 2023|14.5 min read|
The Weight-Loss Myth: Why Exercise Alone Isn’t the Answer
Previously I talked about calories in. Now we need to talk about calories out. There is tremendous pressure on us to exercise to lose weight, and as I said [...]
- Published On: March 22, 2023|14.2 min read|
How Understanding Calorie Intake Can Help You Achieve Your Weight Loss Goals
Calorie critters Today’s article is all about calories. Specifically, calories in. But what even are calories? You may have heard that calories are those devious little critters that sneak [...]