The low carb diet
Low-carbohydrate diets or low-carbohydrate diets are dietary programs that restrict carbohydrate consumption usually for weight management or for the treatment of obesity. Foods high in digestible carbohydrates (eg bread, pasta) are limited or replaced by foods that contain a higher percentage of protein and fat (eg meat, chicken, fish, seafood, eggs, cheese, nuts, Seeds, peanuts, and soy products) and other low-carbohydrate foods (eg, most salad greens), although other vegetables and fruits (especially berries) are allowed. The amount of carbohydrate allowed varies with different low carbohydrate diets.
These types of diets are sometimes ketogenic (that is, restricting carbohydrate intake enough to cause ketosis). For example, the induction phase of the Atkins diet. Some sources, however, take into account less restrictive variants in carbohydrates.
In addition to obesity, low-carbohydrate diets are often used as treatment for other conditions, especially diabetes and epilepsy, as well as chronic fatigue syndrome and polycystic ovary syndrome.
Early Carbohydrate Diet
Going back a bit in the history of low carbohydrate diets, some anthropologists believe that early humans were hunter-gatherers who consumed diets high in protein and fat and low in nutritious carbohydrates (although their diets were high in fiber). In fact, some isolated societies that exist today consume these types of diets. The advent of agriculture led to the rise of civilization and the gradual increase of carbohydrate levels in the human diet. The modern age has experienced a particularly strong increase in the levels of refined carbohydrates in Western societies.
In 1863 William Banting , an English undertaker for the obese and coffin maker, published “Letter on Corpulence addressed to the public” in which he described a diet to control weight by suppressing bread, butter, milk, sugar, Beer and potatoes. His book was widely read, to the extent that some people use the term “Banting” for the activity that is generally called “dieting.”
In 1967, Dr. Irwin Stillman published the “Fast Doctor Diet for Weight Loss”. The “Stillman diet” consists of a high protein content and low in carbohydrates and fat. It is considered as one of the first low carbohydrate diets popular in the USA. Other low-carbohydrate diets in the 1960s included the Air Force Diet and The Diet Drinking Man’s Diet. The Austrian doctor Dr. Wolfgang Lutz published his book Leben Ohne Brot (Life without bread) in 1967, without much repercussion.
In 1972, Dr. Robert Atkins published The Revolutionary Diet of Dr. Atkins Diet Revolution, who advocated a low-carbohydrate diet had been successfully used in treating patients in the 1960s. The book had a Certain success, but, due to research at that time suggesting risk factors associated with excess fat and protein, was widely criticized by the conventional medical community as dangerous and misleading, which limited its appeal at the time. Other critics pointed out that Dr. Atkins had done an unrealistic investigation and relied solely on anecdotal evidence. Later that decade, Walter Voegtlin and Dr. Herman Tarnower published books defending the Paleolithic Diet and the Scarsdale Diet, respectively, each with moderate success.
The concept of the glycemic index was developed around 1981 by Dr. David Jenkins, to account for variations in the rate of carbohydrate digestion (for example, sugar in cooked carrots has a faster effect than Pure glucose). This concept classifies foods according to the rapidity of their effect on blood sugar levels, with a rapid digestion of simple carbohydrates that cause a more acute increase and slower digestion of complex carbohydrates like whole grains. It has also been expanded concept to include the amount of carbohydrates actually absorbed, as a tablespoon of cooked carrot is less important in general than a large baked potato (pure starch, which absorbs glucose),
Low-carb diets since 1990
In the 1990s Dr. Atkins published Dr. Atkins New Diet Revolution and other physicians began publishing books based on the same principles. This has been called the “low carbohydrate craze” principle.
During the 1990s and early 2000s low carbohydrate diets became some of the most popular diets. This affected some food manufacturers and restaurant chains.
Some in the medical community denounced low carbohydrate diets as a dangerous trend. It is, however, valuable to keep in mind that many of these same physicians and institutions at the same time began quietly altering their own advice to be closer to the recommendations of low carbohydrate diets (eg, Eat more protein, eat more fiber and less starch, reduce children’s juice consumption).
Many diet gurus who appeared at that time intentionally distanced themselves from Atkins and low carbohydrate intake (due to controversies) even though their recommendations were based largely on the same principles (eg diet Of the area). As a result, it is often a matter of debate that diets are very low in carbohydrates and which are not. An increasing number of clinical studies on the efficacy and safety (pro and anti) of low carbohydrate diets were also published in the 1990s and 2000s.
After 2004 the popularity of this diet trend began to decline significantly, although it remains very popular.
Methodology and theories of the low carbohydrate diet
The term “low carbohydrate diet” is today more strongly associated with the Atkins diet. However, there are a number of diets that share the same principles to varying degrees (for example, the Zone Diet, The Diet Go Lower Diet, The Earth Diet, and The South Beach Diet). Therefore, there is no widely accepted definition of what constitutes a low carbohydrate diet. It is important to note that the level of carbohydrate consumption defined as low in carbohydrates by medical researchers may be different from the level of carbohydrates defined by dietary advisers. For the purposes of this discussion,
Although low-carbohydrate diets were originally created based on the effectiveness of anecdotal evidence, there is at present a much more theoretical basis on which these diets are based. The key scientific principle underlying these diets is the relationship between carbohydrate consumption and the subsequent effect on blood sugar (glucose in the blood) and the production of certain specific hormones. Blood sugar levels in the human body should be kept within a fairly narrow range to maintain health. The two major hormones related to the regulation of blood sugar levels, produced in the pancreas, are insulin, which lowers blood sugar levels (among many other effects, mostly of great metabolic importance), and The glucagon,
In diets in general, most Westerners (and many others) are high enough in nutritious carbohydrates that almost all meals evoke the secretion of insulin by the beta cells in the pancreas, the carbohydrates that are digested to produce glucose in the Bloodstream are the main control of insulin secretion. Another aspect of insulin secretion is the control of ketosis, in the non-ketostic state, the diet stores the fat of the human body in fat cells (ie, adipose tissue) and preferably uses glucose as a cellular fuel. In contrast, low-carbohydrate diets, or more properly, diets that are very low in nutritious carbohydrates, evoke less insulin (to cover the glucose ingested in the blood), Leading to longer and more frequent episodes of ketosis. Some researchers suggest that this causes fat to be removed from the body, although this theory remains controversial, as far as lipid (ie fat and oil) excretion is concerned and not fat metabolism during Ketosis
Proponents of the low-carbohydrate diet generally recommend reducing nutritious carbohydrates (commonly known as “net carbohydrates,” meaning grams of total carbohydrates by non-nutritious carbohydrates at very low levels. Some recommend levels below 20 grams of “net carbohydrates” per day, at least in the early stages of the diet (by comparison, a single slice Of white bread usually contains 15 grams of carbohydrates, almost entirely starch.Institute of Medicine recommends a minimum intake of 130 grams of carbohydrate per day (FAO and WHO also recommend that most of the food energy come from carbohydrates).
Low carbohydrate diets often differ in the specific amount of carbohydrates allowed, whether certain types of foods are preferred, occasional exceptions allowed, etc. In general, everyone agrees that processed sugar must be eliminated, or at least greatly reduced, and in the same way generally discourage highly processed grains (white bread, etc.)
They also greatly vary their recommendations regarding the amount of fat allowed in the diet, although today’s most popular versions (including Atkins) generally recommend a maximum of moderate fat intake. The American Academy of Family Physicians defines low-carbohydrate diets as diets that restrict carbohydrate intake from 20 grams to 60 grams per day. Atkins (in later stages) and some other low carbohydrate diets exceed the definition of the 60 gram limit by this group.
Although low-carbohydrate diets are most commonly discussed as a method for weight loss, some experts have proposed using low-carbohydrate diets to mitigate or prevent diseases ranging from diabetes to epilepsy. In fact, it has been argued by some that it is the increase in carbohydrate consumption, especially refined carbohydrates, which has caused the epidemic levels of many diseases in modern society (though not proven).
There is also a category of diets known as low glycemic index diets (low GI diets) or low glycemic load diets (GI diets), in particular the low glycemic index diet by Brand-Miller.
In fact, low carbohydrate diets can also be low glycemic load diets (and vice versa) depending on the carbohydrates in a particular diet. In practice, however, “low GI” / “low glycemic load” diets differ from “low-carbohydrate” diets. First, low carbohydrate diets treat all nutritional carbohydrates as having the same effect on metabolism, and they generally assume that its effect is predictable. Low-GI / low-GL dielets are based on the change in measurement of blood glucose levels in various carbohydrates – these vary markedly in laboratory studies. Differences are due to poorly understood differences between digestive foods. Nevertheless,
Another type of diet-related, low-insulin-level diet is similar, except that it relies on direct measurements of insulemic responses (ie, the amount of insulin in the bloodstream) to food instead of response (The amount of glucose in the bloodstream). Despite the recommendations that the diet mostly involves reducing nutritious carbohydrates, there are some low carbohydrate foods that are not recommended (eg, beef). Insulin secretion is stimulated (but with less force) by dietary intake. Just as glycemic index diets have the difficulty in predicting the secretion of insulin from any particular meal,
Studies on the effects on health
Because of the great controversy regarding low-carbohydrate diets and even disagreements in interpreting the results of specific studies, it is difficult to objectively summarize the research in a manner that reflects the scientific consensus. Although there has been some research done throughout the twentieth century, most of the directly relevant scientific studies have taken place in the 1990s and early 2000s and as such are relatively new. Researchers and other experts have published articles and studies ranging from promoting the safety and efficacy of these diets to questioning their long-term validity to openly condemning them as dangerous.
Until recently, a major criticism of the dietary trend has been that there were no studies evaluating the effects of diets beyond a few months. However, studies are emerging that evaluate these diets for much longer periods, controlled studies of up to two years and survey studies of up to two decades.
In 2003, a meta-analysis that included randomized “low-carbohydrate” controlled trials found that low-energy diets did not appear to be at least as effective as low-fat diets to induce weight loss for up to 1 year. “A 2007 study by JAMA to compare the effectiveness of the Atkins diet, another low-carbohydrate and several other popular diets concluded that” women in this study, overweight and obese premenopausal women were assigned to follow the Atkins diet who had the highest intakes Lower carbohydrates, lost more weight and with more favorable experiences with overall metabolic effects at 12 months than women assigned to follow Zone, Ornish, or LEARNING diets.
A July 2009 study of current eating habits associated a low-carbohydrate diet with obesity, although the study did not draw explicit conclusions about the cause.
Potential favorable changes in triglyceride and high-density lipoprotein cholesterol values should be weighed against possible unfavorable changes in low-density lipoprotein cholesterol when considering low-carbohydrate diets to induce loss of weight. A 2008 review of systematic randomized controlled trials comparing low-fat / low-calorie diets with low-calorie diets found that weight, HDL-cholesterol, triglycerides, and systolic blood pressure measurements were significantly higher in the groups that Followed low carbohydrate diet . The authors of this review also found a higher dropout rate in the groups with low fat diets,
A study of more than 100,000 people in over 20 years in the Nurses’ Health Study showed that a low-carbohydrate, high-vegetable diet with a high proportion of proteins and oils from plant sources Mortality with a risk ratio of 0.8. In contrast, a diet low in carbohydrates with sources of much protein and animal fats increases mortality, with a ratio of 1.1.
Other health effects
In addition to research on the effectiveness of diets, some research has directly addressed other areas of health affected by low-carbohydrate diets. Contrary to popular belief that low-carbohydrate diets damage the heart, a couple of studies confirmed that people who eat low-carb, high-fat and protein diets had the same or lower risk of coronary heart disease .
Other studies have found possible benefits for people with diabetes, cancer and autism. The ketogenic diet, with 80% of the energy of fat and much of the rest of the proteins, has been used since the 1920s to treat epilepsy. More effective modern anticonvulsant medications mean that it is now used only for children with difficult to control epilepsy, and may be a concern for such issues as stunting of these children.