NON-CONVENTIONAL DIETS
A. Low Carbohydrate Diets
Diets that contain less than 80-100 grams of carbohydrates, called LCD (low carbohydrate diets) or cetogenic diets have been used for a long time in the treatment of convulsive attacks in children and to reduce body weight. The most well known is the Atkins diet, originally published in 1973, but has gained popularity recently. It consists of a restriction of carbohydrates to less than 10% of the energy consumed in a day, without restrictions to fats or proteins.
This type of diet has not gained popularity for many professionals specialized in the area of obesity, probably because of the lack of studies that analyze the short and long term metabolic effects. However, since 2003 there have been 7 adult patient studies that compare the effect on the composition of the body and metabolic profile of LCD and conventional diets with fat restrictions.
The mechanisms that LCD use to lose weight are not entirely known, but there have been various factors proposed. On one hand, these diets induce a decrease in ingestion between meals. Diets rich in carbohydrates (more than anything simple carbohydrates) cause a rapid elevation in glucose and insulin, stimulating appetite and snacking between meals. In addition, LCD induces cetosis through the metabolism of fats to be transformed into acetones (usable as a source of energy) that also have a reducing effect on appetite. On the other hand, these diets are rich in proteins and fat and it has been demonstrated that proteins also have a high-powered filling effect, superior to that of carbohydrates. But we cannot forget that, for simplicity and monotony, the adherence to this diet lessens and the individual tends to eat less.
LCD are not extensive in their risk factors. The most controversial is its effect on the lipid profile. It has been widely demonstrated that conventional diets low in fat decrease total cholesterol and LDL-cholesterol and that, compared to these diets, LCD improve the triglycerides, HDL-cholesterol and sensitivity to insulin. However, a light increase in total cholesterol and LDL, well-known cardiovascular risk factors, due to a greater intake of cholesterol and saturated fat, give way to restrictions to the prescription of this type of diet. Other observed effects are due to the increase in the consumption of proteins, a decrease in fiber in the diet and the difficulty to maintain lost weight in the following year, and even more so when the patients return to a traditional balanced diet.
B. Cetogenic Diets
These diets give you all of the basic groups, but in a form of ingestion that separates time of consumption. The ones that stand out are the Hay and Montignac diets, where the combination of carbohydrates with proteins and fats are not allowed. One extreme version of this is the Antoine diet that only permits eating one type of different food each day (Monday: meat, Tuesday: milk products, etc.). Many of these diets have fundamentals that are physiologically correct and healthy, mixed with other recommendations that are scientifically unproven.
C. Vegetarian Diets
The majority of these cases are not in it of themselves diets to lose weight, but a lifestyle choice. These diets eliminate, in a complete or incomplete form, products that come from animals, giving way to variants and sub-variants.
From what we know concerning nutritional content, it is necessary to keep in mind not only the type of vegetarian diet, but the grade and the duration of which it is followed is important in evaluating benefits or dangers.
The general types of vegetarian diets are the following:
Vegetarian diets tend to contain less proteins, saturated fats, cholesterol and total calories, but are richer than the typical diet in fiber and w-3 and w-6 fatty acids. Many studies have shown a lower rate of illness and greater survival rate in vegetarians. That is to say, it appears that the adscription to a vegetarian diet results in a general improvement to health. The benefits include a lower chance of cardiovascular disease, hypertension, being overweight or obese, less chance of death because of renal diseases and lower chance of tumors.
Generally, a well-selected lacto-ovo-vegetarian diet can achieve all of the nutritional necessities in the majority of people, with the exception of vitamin B-12. Vitamin B-12 is found in eggs and the derivatives of milk, but the levels of the vitamin in the blood are not as high as those who consume a typical diet. Milk can be fortified with vitamin D, but not cheese and other derivatives. The iron contained in many vegetable elements is not absorbed well by the intestines, although this can be improved if there is an increase in the consumption of vitamin C (citrus, tomato, peppers, or supplements). A strict vegetarian diet cannot supply the necessary quantities of calcium, iron, and vitamins for children, women with normal menstruation and those who are pregnant.
Finally, the macrobiotic diet should be included. This diet divides foods into ying (passive) and yang (active), considering that a balance between the two is optimum. In certain cases of strict macrobiotic diets, grave and numerous nutritional deficiencies have been seen.
D. Others
There are numerous diets that appear each season validated by famous personalities, with no scientific base and that are highly deficient in nutrients. The ones that stand out are the Mayo Clinic (negated by this medical institution), the Harrop diet (milk and bananas), cronodiet (allowing for eating, according to determined hours of the day, certain foods in unmeasured quantities that do not make one fat while others do not), the astronaut diet (negated by NASA, multi-deficient and very low in fiber), etc.