Low-carbohydrate diets are defined as those that provide less than 45% of their energy from carbohydrates [74,75]. Some authors define a low-carbohydrate diet as one containing 50 to 150 grams of carbohydrates per day [74]. Some studies suggest that these diets have beneficial effects when calorie restriction is used; however, without it, these benefits are lost. Furthermore, many studies do not consider whether carbohydrates come from vegetables, fruits, and whole grains or from processed foods, and it is known that different metabolic effects are achieved depending on the carbohydrate source [75]. Some reviews have concluded that low-carbohydrate diets have short-term beneficial effects on weight loss, blood glucose, and insulin levels. However, data supporting their efficacy, safety, and long-term health benefits are lacking. Furthermore, due to reduced fiber intake, adverse effects on stool quality and the production of short-chain fatty acids by colonic flora have been observed. If these effects persist over a long period, they can lead to intestinal diseases.
Weight Loss: Lifestyle Changes and Pharmacotherapy
Low-carbohydrate diets promote weight loss by promoting ketogenesis, or reducing the insulin response, typically by limiting carbohydrate intake to <20% of daily calories. The low-carbohydrate approach was popularized with the Atkins diet, in which carbohydrate intake was initially limited to 20 g per day and gradually increased to 50 g per day. <sup>37</sup> The ketogenic diet is a variant of this approach, in which carbohydrate intake is limited to 20–30 g per day.
Summary of Various Diets for the Treatment of Obesity
- Low-carbohydrate and very-low-carbohydrate diets provide 60 to 130 g/day and 0 to 60 g/day, respectively. General diets based on this model include the Atkins Food, the South Beach Diet, and the Dukan Diet.
- In general, low-carbohydrate diets in the UK are low in fiber, thiamin, folate, potassium, calcium, magnesium, iron, and vitamins A, E, and B6.
Overall, carbohydrate restriction has been shown to effectively stimulate weight loss over 6 months, to a greater extent than low-fat diets. However, this effect was not sustained over 12 months.¹ Early weight loss may be due to fluid loss and glycogenolysis. A recent study has also shown that low-carbohydrate diets can cause cognitive impairment due to the lack of energy from blood glucose, which is normally produced by breaking down carbohydrates. Furthermore, the study showed that low-carbohydrate diets affect myocardial energy substrates and insulin signaling, which contributes to the protection of ischemic myocardium. Low-carbohydrate diets cause increased levels of 3-hydroxybutyrate and decreased levels of circulating insulin, which impair ventricular function, as well as decreased myocardial glycogen stores and utilization. 2 Low-carbohydrate diets have also remained revealed to prolong the QT interval on the ECG, which is clinically relevant due to the increased risk of ventricular arrhythmia and rapid death.
Association between dietary patterns and cardiovascular diseases: A review
A low-carbohydrate diet (LCD) is an eating pattern rich in protein, fat, and vegetables, with strictly restricted carbohydrate intake. While it does not strictly restrict carbohydrate intake, current research suggests that an actual daily carbohydrate intake of less than 130 g or a carbohydrate intake of less than 10% of total calories has a significant impact on weight loss or the development of type 2 diabetes (T2D). 24, 51 The ketogenic diet is an extreme example of a low-carbohydrate diet, often requiring 20–50 g of carbohydrates per day, and sometimes less than 20 g, with a greater emphasis on fat intake. It has been recognized as a medical diet for the treatment of epilepsy. As one of the most popular dietary regimens in recent years, the low-carb diet has shown promising results in reducing weight and cardiovascular disease risk, although controversy persists. Eight years ago, Dr. Unwin, a British physician, met by chance a 55-year-old patient who had suffered from type 2 diabetes for 14 years and was at high risk for cardiovascular disease. The patient has steadily lost a total of 16 kg over the past seven months and has successfully stopped taking all four prescribed medications (aspirin, metformin, perindopril, and simvastatin) thanks to the low-carb diet. In his latest study, he found that after continuing the low-carb diet (average duration: 33 months), 77% of patients with type 2 diabetes for less than one year achieved diabetes remission, and in those with type 2 diabetes for more than 15 years, the remission rate dropped to 20%. A meta-analysis of 1141 obese patients found that LC was associated with significant reductions in major cardiovascular risk factors, including: weight (-7.04 kg), body mass index (BMI: -2.09 kg/m2), waist circumference (-5.74 cm), systolic blood pressure (-4.81 mmHg), diastolic blood pressure (-3.10 mmHg), plasma triglycerides (-29.71 mg/dL), and elevated high-density lipoprotein cholesterol (1.73 mg/dL).54 However, the authors note that it is not yet known whether long-term low-carbohydrate diets also have benefits.54 However, there is controversy regarding the long-term effects of LC. In a pooled report based on population-based and prospective cohort studies, participants in the lowest quartile of carbohydrate intake had the highest risk of all-cause mortality (32%), cardiovascular disease (50%), cerebrovascular disease (51%), and cancer (36%). Notably, this effect was more pronounced in non-obese individuals.<sup>55</sup> Similar results were found in these studies. A prospective cohort study of Swedish women found that regular adherence to a low-carbohydrate, high-protein diet, regardless of the nature of the carbohydrate or the protein source, was associated with an increased risk of CVD. 58 Another study also found that adherence to a low-carbohydrate, high-animal-fat, and high-protein diet was associated with increased all-cause and CVD mortality after myocardial infarction. 59 However, studies in different populations have come to different conclusions. Results of a low-carbohydrate diet in Japanese women showed that a moderate low-carbohydrate, high-protein, and high-fat diet was significantly and inversely associated with CVD and all-cause mortality in women. 60 In this article, we continue to find that PA significantly reduces CVD risk and mortality in certain ranges. This can be influenced by many factors, such as the population in which the indications are observed (obesity or type 2 diabetes), the source of carbohydrates, fats and proteins, the duration of the GC and the ethnic group.
Obesity therapy
Low-carb diets are widely known as weight-loss methods. They include the Atkins, South Beach, and Dukan diets. The Food and Drug Management (FDA) has not clearly defined low-carb diets, but most only consume about 10% of their calories from carbohydrates. They promote eating controlled amounts of nutrient-dense foods and eliminating refined carbohydrates. Foods such as meat, poultry, fish, butter, and vegetable oils are not restricted, but quality is more important than quantity. Studies have shown that people on low-carb diets lost meaningfully more weight than those on low-fat diets during the first 6 months, but the difference in weight loss was not sustained over a year. Low-carb diets may be more difficult to maintain long-term. Considering all these factors, low-carb and low-fat diets are generally equivalent in effectiveness.
Conclusion
The low-carb diet has gained widespread popularity thanks to its potential for weight loss, improved blood sugar control, and optimized metabolism. By reducing carbohydrate intake and prioritizing protein and healthy fats, this diet may help some people manage conditions such as type 2 diabetes, obesity, and insulin resistance. However, it may not be suitable for everyone, and long-term adherence can be difficult without proper planning.
Before making significant dietary changes, it is important to consult with your doctor or registered nutritionist to ensure the diet fits your nutritional needs and health goals. If followed responsibly and tailored to your individual needs, a low-carb diet can be an effective and sustainable approach to improving overall health.