Low carb diets have been used as a weight loss tool and a way to manage chronic metabolic conditions for many years. However, keto, paleo, Atkins and other similar dietary approaches have as many staunch fans as they have passionate opponents. Hotly debated in the scientific community and among regular dieters, low-carb diets have generated controversy – and misinformation. So what are they, and what are the pros and cons of restricting your carbohydrate intake?
According to the journal Frontiers in Nutrition (opens in new tab), any diet that provides approximately 20g to 120g of carbohydrates a day is considered low-carb. Within that range, there are subtypes. We can classify low carb diets based on their calorie content, macronutrient composition (for example, keto and Atkins) or even the preferred food types (such as paleo or alkaline diet). Although they all appeared at different times throughout history, they all have a similar impact on our bodies.
Here, we’ll take a closer look at the history of low carb diets, their potential health benefits and any risks associated with cutting your carbohydrates.
A history of the low carb diet
Low-carbohydrate diets have their origins in the distant past. It’s been suggested that in 776BC, Greek Olympic athletes were consuming a protein heavy, low carb diet to maintain their strength, muscle mass and sports performance. However, it was only in the second half of the 19th century that these dietary patterns became more mainstream. In 1863, William Banting published his Letter on Corpulence, Addressed to the Public (opens in new tab), in which he promoted the benefits of a low carb diet for weight loss and optimal health. Banting is now considered to be ‘the father of the low carb diet’.
Ketogenic diets gained traction in the early part of the 20th century, when physicians discovered the beneficial effects of carb restriction on the symptoms of epilepsy (opens in new tab) in children. When people realized that low-carb diets may also help them lose weight, their popularity skyrocketed. In 1927, Arctic explorer Vilhjalmur Stefansson started promoting a 15%-20% carb diet (opens in new tab), which he based on his observations of the daily habits of Inuits in the Arctic. Not long after, American nutritionists decided to class starchy foods as acid forming (opens in new tab). To counteract these allegedly unhealthy properties of complex carbohydrates, they started promoting a new, revolutionary low carb dietary pattern: the ‘alkaline diet’.
This led way to more low carb diets in the second half of the 20th century, including the ‘cabbage soup diet’ and the Atkins' diet.
In 2003, Dr Arthur Agatston wrote The South Beach Diet, in which he promoted eating mostly foods with low glycemic index and glycemic load (foods that don’t tend to spike blood glucose levels). This was soon followed by The Blood Sugar Diet by Dr Michael Mosley, which promoted a low-carb Mediterranean diet with or without intermittent fasting days and the option of restricting energy intake to 800 calories a day.
- Related: Which vegetables are low in carbs?
What are the benefits of a low carb diet?
The basic principle behind effective weight loss is that you have to achieve and consistently maintain a calorie deficit. No fad diets, supplements or superfoods will be effective when you consume more energy than your body needs. That said, there is evidence (opens in new tab) that keeping your carbohydrate intake low and protein consumption high could help you to lose weight faster.
According to a meta-analysis published in the Nutrients (opens in new tab) journal, in comparison with classic low fat diets, low carb diets tend to produce better outcomes in terms of changes to body weight. Similarly, multiple intervention studies (opens in new tab) have reported that combining low carb diets and exercise may have beneficial effects on the body weight and waistline of overweight and obese adults.
Type 2 diabetes and insulin resistance
Type 2 diabetes and insulin resistance are among the biggest public health challenges of our time. Diets rich in sugars, simple carbohydrates and processed foods – as well as a lack of physical activity, combined with psychological stress – are some of the drivers behind this growing epidemic.
Scientists have been testing lifestyle interventions that could treat these chronic conditions, one of which is switching to a low carb diet. This is because evidence behind their ability to positively impact insulin metabolism and blood sugar levels is growing. According to a review recently published in the Current Diabetes Reports (opens in new tab), following a ketogenic diet for three weeks can lead to significantly improved HbA1c results (measurement of blood glucose levels) and a reduced need for diabetic medications.
Furthermore, adhering to a low-carb diet for six months or more may even lead to remission of type 2 diabetes without any adverse consequences, as described in a meta-analysis recently published in The British Medical Journal (opens in new tab). Nevertheless, researchers stress the fact that a definitive causal link between ketogenic diets and diabetic disorders has not been fully established. If you have diabetes, speak to your doctor before making any changes to your diet.
Nutrition is one of the biggest factors affecting our gut health and even small tweaks to our diet can trigger far-reaching changes to the number and type of microbes. Low-carbohydrate diets have been shown (opens in new tab) to influence the composition of our gut microbiota, favoring the growth of species that may have a positive impact on our gut-brain axis and our nervous system. According to a review published in the Reviews in the Neuroscience (opens in new tab) journal, low-carb diets may play an indirect part in preventing and/or treating central nervous system disorders, including epilepsy, Parkinson's disease, Alzheimer's disease, autism and multiple sclerosis.
A high intake of simple carbohydrates and sugar can lead to an increased risk of developing and dying from cardiovascular diseases, according to research in the Mayo Clinic Proceedings (opens in new tab) journal. As such, many scientists have been exploring the potentially beneficial links between low carb diets and cardiovascular risk factors.
According to analysis published in the Obesity Reviews (opens in new tab) journal, a low carbohydrate intake is associated with a reduction in bodyweight, a smaller waist circumference and lower blood pressure. On the other hand, hypoglycemia (low blood sugar level that can happen following a restrictive ketogenic diet) has been shown to increase the likelihood of adverse cardiovascular events, as described in The Lancet’s Diabetes & Endocrinology (opens in new tab) journal.
Scientists have been exploring the ability of ketogenic diets to reduce neuroinflammation – an inflammatory response within the brain or spinal cord that has been shown to be a major trigger of neurodegenerative conditions.
According to a review published in Epilepsy Research (opens in new tab), factors contributing to the anti-inflammatory properties of this diet include the presence of ketone bodies, calorie restriction, and changes in gut bacteria.
Risks and considerations
Despite their potential benefits, low carb diets can come with some potential risks and considerations. You may find limiting an entire food group to be restrictive, and many people find it difficult to maintain this regime in the long term. If not done carefully, limiting foods with a medium-to-high carbohydrate content may also lead to nutritional imbalances. Low carb diets often provide high amounts of fat and not enough fiber, which may lead to poor metabolic and digestive health.
Low carb diets require planning and preparation. If they’re not done properly, it’s relatively easy to develop nutrient deficiencies.
According to a review published in the Journal of the International Society of Sports Nutrition (opens in new tab), low carb diets may not supply enough B vitamins, vitamin C, vitamin E, vitamin D, iron, calcium and magnesium.
Type 1 diabetes
When it comes to type 1 diabetes, there are serious safety concerns. According to a review in the Cleveland Clinic Journal of Medicine (opens in new tab), severe carbohydrate reduction may cause adults with type 1 diabetes to experience more complications like ketoacidosis (excessive build-up of ketones in the body) and hypoglycaemic episodes.
Many low carb diets promote a high protein intake, which may be potentially dangerous for individuals with kidney problems. According to a review recently published in the Journal of the American Society of Nephrology (opens in new tab), excessive protein consumption may increase the filtration processes in inefficient kidneys, leading to tissue damage and abnormal protein urine levels.
Still, there’s emerging evidence that a low carb diet and associated weight loss could be beneficial for the kidney health of adults with type 2 diabetes. In a Current Opinion in Endocrinology, Diabetes and Obesity (opens in new tab) study, patients with reduced kidney function experienced a slight improvement to their glomerular filtration rate (a measurement used to estimate the rate at which the kidneys filter blood) following a low carb diet intervention. However, these findings need to be treated with caution as other studies (opens in new tab) have not detected similar changes.
Is cutting carbs healthy?
Cutting down on carbs can benefit our cardiovascular and metabolic health. Reducing the intake of this macronutrient can also potentially help us lose weight and improve our mood.
However, this comes with downsides. Carbohydrates are found in many healthy foods, particularly fruits and whole grain products. Cutting down on these means you’ll also have trouble getting enough fiber and vital nutrients, potentially forcing you to resort to supplements.
Although routinely demonized, carbs are the preferred energy source for your brain and not getting enough of them may lead to brain fog and mental exhaustion. They’re also important in boosting sports performance, particularly when it comes to endurance-type activities.
So is cutting carbs healthy? Shortly, yes and no – the answer depends on your individual needs, health status, personal circumstances and abilities. If in doubt, it’s always a great idea to consult a medical professional before starting a low carb diet.