In the constantly changing landscape of dietary trends, the low-carb diet continues to stand its ground as a favoured dietary approach among health-conscious individuals seeking to manage their weight and optimise health and longevity. This dietary approach has gained significant popularity over the past decade for its potential to not only support weight loss but also foster a range of health benefits including enhancing metabolic health, improving cognitive function, stabilising blood sugar levels and reducing the risk of certain chronic diseases.
The merits of a properly balanced low-carb diet are numerous and compelling. Nonetheless, it’s essential to ensure that you’re approaching it correctly to avoid nutritional deficiencies and navigate potential hurdles that can arise when making substantial dietary changes.
What is a low-carb diet?
A low-carb diet is a nutritional approach that focuses on reducing the intake of carbohydrates, particularly refined and simple carbohydrates such as sugars, processed grains and starchy vegetables. A well- structured low-carb diet emphasises the consumption of good-quality protein, healthy fats and natural nutrient-dense carbohydrates from certain vegetables, fruits and whole grains, in moderation.
Carbohydrates are one of the three main macronutrients, along with fats and proteins. They are broken down into glucose (sugar) in the body, which serves as a primary source of energy. However, consuming excessive amounts of carbohydrates, especially refined ones, can lead to spikes in blood sugar levels and potentially contribute to weight gain and various health issues.
A low-carb diet typically involves reducing carbohydrate intake to a certain level, often ranging from 20 to 100 grams of net carbohydrates per day, depending on the specific variation of the diet. Net carbohydrates, which are the number of carbs the body absorbs, are calculated by subtracting fibre and certain sugar alcohols from the total carbohydrate content, as these components have a lesser impact on blood sugar levels.
Variations of low-carb diets
There are several variations of a low-carb diet, each with varying levels of carbohydrate restriction. However, most involve restricting carbohydrate intake to less than 30–40 per cent of your total daily calories.
Low-carb, high-protein diet
Following a low-carb, high-protein diet entails a macronutrient breakdown of approximately 30–35 per cent protein, 20 per cent or less carbohydrates and around 45–50 per cent fat. For each meal, it’s recommended to include one to two palm-sized servings of good-quality protein, such as organic chicken, oily fish or grass-fed meat.
High-fat, low-carb diet
The high-fat, low-carb diet approach maintains a moderate reduction in carbohydrate intake while increasing the consumption of beneficial fats. This diet prioritises whole foods and natural fats, which help promote sustained energy levels and satiety.
Despite the common association of dietary fat with body fat, consuming sufficient amounts of healthy fats in your diet can actually offer significant overall health benefits. Unsaturated fats found in oily fish, avocados, olive oil, chia seeds and flaxseeds can help boost heart health and have been linked to improvements in triglyceride levels, blood pressure and weight loss.
The ketogenic or keto diet
The ketogenic diet is an extremely low-carb, high-fat diet designed to induce a state of ketosis, where the body primarily uses ketones (the by-products of fat metabolism) for fuel instead of glucose. The typical macronutrient ratio is about 70–75 per cent fat, 20–25 per cent protein and 5–10 per cent carbohydrates. In general, ketogenic diets typically limit daily net carb intake to just 20–30 grams.
Compared to high-protein, low-carb diets, the ketogenic diet is considered a “moderate” protein diet. It’s important not to overconsume protein on the ketogenic diet because this can interfere with your ability to produce ketones.
The rationale behind maintaining a low carbohydrate intake is to compel your body to shift its primary energy source from glucose derived from carbohydrates to fat. Fat is a highly energy-dense molecule, and part of this energy is converted into ketones. Ketones are a usable energy source for most cells in your body, serving as an alternative to glucose. When your body transitions to relying on fat and ketones as its primary energy supply, you enter a state known as nutritional ketosis.
It’s worth noting that the degree of carbohydrate restriction required to achieve and maintain ketosis can vary from person to person. If you lead an active lifestyle and engage in regular exercise you’re generally more likely to maintain ketosis while allowing a somewhat higher carbohydrate intake. Conversely, if you have a sedentary lifestyle and struggle with excess weight, it is advisable to lean towards a lower carbohydrate intake to ensure a consistent state of ketosis.
The ketogenic diet has been around for decades, recommended by neurologists for epilepsy patients. More recently it has been used to help manage a variety of other conditions including cancer, diabetes and Alzheimer’s disease.
Research has demonstrated that adopting a ketogenic diet has positive effects on blood sugar regulation, cholesterol profiles, appetite control, neurological health and weight management.
Low-sugar, low-carb diet
A low-carb, low-sugar diet minimises consumption of starches and sugars to propel the body into fat-burning mode. This diet focuses on reducing added sugars from foods like confectionery, sweetened beverages, refined grains and processed foods, and emphasises healthy fats and high-quality protein from wholefoods.
Health benefits
When done correctly research shows that a nutritious and well-balanced low-carb diet poses few health risks. In fact, low-carb diets such as the ketogenic diet have been linked to fast weight loss, reduced hunger, better control over insulin and blood sugar, enhanced cognitive performance, lower risk for heart disease factors and reduced risk for certain types of cancer.
Weight loss
One of the primary reasons people adopt a low-carb diet is for weight loss and management. Many people experience fast weight loss on a low-carb diet without feeling hungry or having to count calories. By reducing your carbohydrate intake and relying more on fats and proteins for energy, the body is encouraged to burn stored fat, leading to a reduction in body weight and body fat percentage.
When we consume foods containing sugars and carbohydrates, the hormone insulin is released as a reaction in order to reduce blood sugar levels. Insulin is commonly known as the “fat-storage hormone” because it promotes the storage of excess energy as fat and inhibits the breakdown of stored fat. By reducing carbohydrates in the diet, we can inhibit the release of insulin, thus preventing fat storage.
A reduced presence of insulin in the bloodstream compels the body to deplete its glycogen reserves (stored glucose) and then tap into the stored fat reserves nestled within our adipose tissue for continuous energy supply.
Balance blood sugar levels and improve insulin sensitivity
Low-carb diets can help stabilise blood sugar levels, making them particularly beneficial for individuals with type-2 diabetes or those at risk of developing diabetes.
By consuming fewer carbs, you can maintain more stable blood sugar levels. This helps prevent spikes in blood sugar and reduces insulin production. Over time, improved blood sugar control can lower the risk of developing type-2 diabetes. A low-carb diet can also enhance insulin sensitivity. When cells become more responsive to insulin, they can more effectively take up glucose from the bloodstream, reducing the need for higher insulin levels. Improved insulin sensitivity is key to diabetes prevention. Many studies have shown that a low-carb diet is an effective tool in the treatment and prevention of type-2 diabetes.
Obesity is a significant risk factor for type-2 diabetes. Losing excess weight or maintaining a healthy weight through a low-carb diet can reduce the likelihood of developing diabetes. Low-carb diets may help manage insulin resistance and hormonal imbalances associated with polycystic ovary syndrome (PCOS).
Improved heart health
Many low-carb diets emphasise the consumption of healthy fats, such as those found in avocados, raw nuts and seeds and fatty fish. These beneficial fats are associated with improved heart health by increasing “good” HDL cholesterol levels and reducing triglycerides.
Reduced risk of metabolic syndrome
Metabolic syndrome is a cluster of conditions, including high blood pressure, high blood sugar levels, excess abdominal fat and abnormal cholesterol levels, that increase the risk of heart disease and type-2 diabetes. Low-carb diets can help mitigate these risk factors and improve overall metabolic health.
Appetite control
A significant advantage of adopting a low-carb or keto diet lies in the increased consumption of healthy fats and proteins instead of sugars and carbohydrates. Protein and fat-rich foods help stimulate the release of leptin, often referred to as the “satiety hormone”. Leptin is produced by fat cells and plays a crucial role in signalling to the brain that the body has received an adequate supply of energy and that there is no immediate need for more food, promoting a feeling
of fullness and contentment. Leptin helps you feel satisfied after a meal and reduces cravings, making it easier to control portions and reduce overeating. This can be particularly helpful for weight management and reducing mindless snacking.
In contrast to leptin, ghrelin is known as the “hungry hormone”. When you consume carbohydrates and sugars, especially in excess, it can lead to fluctuations in blood sugar levels, causing ghrelin levels to rise. This increase in ghrelin triggers feelings of hunger and cravings for more of these energy-dense foods. A low- carb or keto diet helps keep ghrelin levels in check. This means that you are less likely to experience intense hunger and cravings, contributing to a greater sense of satisfaction with your meals.
Better digestion
Reducing sugar intake through a low-carb diet can promote improved digestive health because sugar provides food for “harmful bacteria” that can flourish in the gastrointestinal tract. Excessive sugar and carbohydrate consumption can potentially lead to the onset of conditions such as candida overgrowth, irritable bowel syndrome (IBS) and exacerbation of symptoms associated with leaky gut syndrome. According to a 2008 Study published in the Journal of the American Gastroenterological Association, individuals with IBS reported improvements in symptoms including abdominal pain, stool habits and quality of life after following a very low carbohydrate diet with 20 grams of carbohydrates a day.
Improved cognitive function
The brain predominantly comprises fatty acids and relies on a consistent supply of fats from your diet to maintain proper brain function, along with regulating mood and hormones. Although a sugary or high-carb meal may initially provide a feeling of alertness, it’s often followed by a rapid crash, leading to fatigue, irritability and mood swings. Sugar can be addictive and exerts significant effects on the brain, notably in terms of intensifying cravings, anxiety and fatigue. An unhealthy diet high in sugar and low in healthy fats is associated with lower cognitive scores and insulin resistance.
In contrast, specific types of healthy fats, including omega-3 essential fatty acids, serve as antioxidants and precursors to essential brain-supporting compounds and neurotransmitters responsible for controlling functions like learning, memory, mood and energy regulation.
Studies indicate that the ketogenic diet has particular therapeutic potential in safeguarding cognitive wellbeing.
Numerous studies have provided encouraging findings regarding the improvement in the health and wellbeing of individuals diagnosed with Alzheimer’s disease and dementia when prescribed a ketogenic diet.
Help fight cancer
Scientific research demonstrates that a diet abundant in refined carbohydrates and sugar can promote free radical damage and potentially fuel the rapid proliferation of cancer cells. Conversely, low-carb diets, by significantly reducing sugar intake and limiting the consumption of grains and processed foods, may function as a natural approach to helping combat cancer.
Reduce artificial additives and gluten
Many people who consume a typical Western diet follow a high-carb diet loaded with processed foods and added sugars. Therefore one of the other benefits of eating a low-carb diet is that it eliminates many of these unhealthy ingredients commonly added to processed foods such as artificial colours, flavours, sweeteners and hydrogenated fats, and prioritises nutritious wholefoods instead. For those who need to avoid gluten due to sensitivity or coeliac disease, a low-carb diet can help reduce reliance on gluten-containing foods.
Are there any risks associated with following a low-carb diet?
While a well-balanced low-carb diet can offer many health benefits, it’s important to be aware of potential risks associated with this dietary approach. As with any significant dietary change, there are considerations to keep in mind to ensure you’re maintaining a healthy and sustainable eating pattern.
Severely restricting carbohydrate intake can lead to reduced consumption of nutrient-rich foods such as fruits, whole grains and certain vegetables. These foods provide essential vitamins, minerals and dietary fibre that are important for overall health. Without proper planning, nutrient deficiencies could occur.
Low-carb diets may lack the fibre necessary for regular bowel movements. Fibre helps maintain digestive health, and a deficiency can lead to constipation.
Without sufficient carbohydrate intake, the body may break down muscle tissue for energy. Protein is essential to preserve muscle mass, but an extremely low-carb diet could potentially lead to muscle loss if protein intake is inadequate.
Carbohydrates are the body’s primary source of quick energy, especially during high-intensity exercises. Individuals engaged in intense physical activities may find their performance affected by a lack of readily available carbohydrates.
Foods to include
It’s important to approach a low-carb diet in a balanced and sustainable manner. Choosing nutrient-dense non-starchy carbohydrates, incorporating a variety of vegetables and moderate amounts of lower-carb fruits, consuming adequate good-quality protein and selecting healthy fats are all key to reaping the potential health benefits while ensuring you’re meeting your nutritional needs. The specific foods you can eat will depend on the level of carbohydrate restriction you’re following and the type of low-carb diet you’re adhering to.
Here is a general list of foods that are commonly included in various low-carb diets.
Quality protein sources: Grass-fed beef and lamb, organic chicken and turkey, pork, oily fish, organic eggs, organic tofu and tempeh, cottage cheese, full-fat cheese, Greek yoghurt (no added sugar) and plant-based protein sources like beans and legumes (in moderation).
Healthy fats: Avocado, raw nuts and seeds, cold- pressed oils (extra-virgin olive, avocado, coconut, macadamia nut, flaxseed), oily fish (salmon, tuna, mackerel, sardines, trout), butter and ghee (preferably organic and from grass-fed sources) and MCT (medium- chain triglyceride) oil.
Non-starchy vegetables: In general, vegetables that grow above ground tend to be non-starchy and low in carbs. Leafy greens (spinach, kale, lettuce, arugula, dandelion or beet greens, collards, mustard, chicory, endive, radicchio, chard), cruciferous vegetables (broccoli, cauliflower, cabbage, Brussels sprouts), cucumbers, celery, capsicums, zucchini, leeks, asparagus, green beans, mushrooms and bean sprouts. Zucchini noodles make a healthy low-carb spaghetti option. Cauliflower is an excellent low-carb food that can be used instead of rice or mashed potatoes in your diet. Cauliflower contains only two grams of net carbs per cup.
Whole grains: Many low-carb diets typically exclude grains altogether. Nonetheless, some grain varieties are rich in fibre, and you can incorporate them in limited quantities as part of a balanced, carbohydrate-controlled eating plan. This is because foods that are high in fibre contain a lower number of net carbs. Lower-carb grains include steel-cut and whole oats (instead of the processed varieties), quinoa (a pseudo-grain), bulgar (cracked wheat berries), millet and wild rice.
Fruits: Low-carb fruits that can be enjoyed in moderation include blueberries, strawberries, raspberries, blackberries, tomatoes, avocados, lemon, lime, coconut flesh and olives. Avocados are a perfect low-carb fruit, containing only two or three grams of net carbs per serving of around half an avocado.
Dairy and plant-based alternatives: Full-fat unprocessed cheese, unsweetened plant-based milk (almond, coconut, hemp or other nuts), plain Greek or full-fat natural yoghurt (no added sugars) and cream in moderation.
Condiments, sweeteners and flavourings: Herbs and spices, vinegar (balsamic, apple cider), mustard (no added sugars), soy sauce or tamari, salsa (no added sugars), mayonnaise (no added sugars), cocoa powder and pure vanilla bean extract. Stevia and monk fruit powder can be used as a natural low-carb sweetener.
Beverages: Water and sparkling water, herbal tea (no added sugars), black coffee (no added sugars), bone broth, freshly made veggie juices. Low-carb protein smoothies make a nutritious snack or breakfast on a low-carb diet; include a clean no-sugar protein powder (such as whey, collagen, hemp or pea), unsweetened milk (coconut, almond or hemp milk) and frozen berries. Then choose from healthy ingredients such as flax or chia seeds, a spoonful of almond or peanut butter, MCT oil, avocado and a little stevia for extra sweetness.
Foods to avoid
While following a low-carb diet, it’s important to minimise or avoid foods that are high in carbohydrates, especially those that are refined, sugary or processed. Here’s a list of foods that are typically avoided or restricted on a low-carb diet.
Highly processed carbohydrates and refined grains: White rice, white bread, pasta, breakfast cereals (sugary cereals, instant oatmeal), baked goods (cookies, cakes, pastries, muffins), pizza dough, crackers, tortillas, polenta. All types of products made with white flour.
Sugars: Cane sugar (white, brown, raw), maple syrup, agave, molasses and honey. It is also recommended to avoid artificial sweeteners (aspartame, sucralose) when prioritising whole, unprocessed foods.
Sugary foods and snacks: Sugar-sweetened beverages (soft drinks, fruit juices, energy drinks, flavoured milk), confectionary, biscuits, cakes, ice cream, sugary yoghurts, desserts with added sugars, muesli bars, potato chips, pretzels and most protein bars.
Starchy vegetables: Potatoes, sweet potato, beetroot, pumpkin, carrots (include small servings), peas (include small servings), corn and parsnips. Vegetables with more than 5g of carbs per 100g of weight are considered starchy vegetables.
High-sugar fruits: Bananas, grapes, pineapple, watermelon, mangoes, peaches, nectarines, apples, oranges, dried fruits and fruit juices.
Sugary and high-carb condiments: Tomato and barbecue sauce, sweetened salad dressings and pasta sauces.
Processed meats with added sugars: Some sausages and deli meats.
Alcohol: Alcoholic beverages, especially those high in sugars served with soft drinks and sugary mixers.
As with any significant dietary changes, it’s advisable to consult with a healthcare professional such as a nutritionist or dietitian before starting a low-carb diet, especially if you have existing health conditions, so they can provide personalised guidance and help you create a balanced eating plan that meets your nutritional needs and health goals.
