You choose to stop eating carbohydrates, limit fat or fast intermittently. You go from removing things from the menu and you join the fashion of increasing protein, or eat raw meat as if you were in the Stone Age … Each of these diets have attractive peculiarities that lead you to try your luck, but also a hateful thing in common: kilos always come back. Why is there not a list of subsistence allowance What do work? Is it that nobody can give guarantees? Not quite, but a team of Italian scientists who have analyzed the ten most popular diets. His conclusion, published in an article in the magazine Advances in Nutrition, is that only two have a full endorsement of scientific studies – and not only in regards to controlling weight -, six live in the limbo of nuances, and it cannot be said that the remaining two have the backing of scientific research carried out so far.
To make this judgment, the scientists collected 15,000 systematic reviews and meta-analyzes, which are scientific publications that evaluate what is known about a subject according to the available scientific literature and what is the methodological quality of the research in that field of study. In the end, they eliminated most of the studies (it seems that the quality of this type of work is not usually exemplary) and they were left with only 80 jobs. Few. No, enough.
Options to lose weight, reduce cholesterol and control sugar
More than 60% of the European population has ever been on a diet, and one of the most common reasons. According to the new review, Diets that restrict carbohydrates are a winning bet to lose weight in six months; in fact, they are designed for that purpose and to reduce the health risks arising from type 2 diabetes and metabolic syndrome. But scientists have observed that their colleagues do not always establish the same conditions when they investigate the benefits of this diet: the percentage of energy in the form of carbohydrates that they remove from the menu in their studies is between 26% and 45% of calories totals According to the Mayo Clinic, to lose from 0.5 to 0.7 kilos a week you have to cut between 500 and 750 calories a day, all based on limiting the presence of cereals, vegetables that have an important presence of starch and fruit .
“The effectiveness of a diet, however, is not only determined by its ability to induce weight loss in a short time. There are other factors such as nutritional quality and long-term effects on cardiometabolic risk factors that should be considered “, say the researchers. That is why they have included in their work parameters such as blood pressure and lipid profile (which includes markers such as cholesterol levels). With this approach, they have observed that a feeding in which carbohydrates are reduced it produces a possible increase in the levels of total and LDL cholesterol – better known as bad cholesterol. This detrimental effect may be due to “the fact that people on a low-carb diet tend to eat less vegetables and fruits rich in micronutrients and fiber, and more animal-derived foods” – rich in fat and protein – the researchers speculate.
Scientists have also observed a tendency to increase LDL cholesterol levels in people who follow a protein-rich diet, perhaps by concentrating a high intake of saturated fat and low in fiber. According to the work, the combination potentially contributes to raising the levels of LDL, glucose and HbA1c, a marker used to measure the level of blood sugar and that interests doctors to detect type 2 diabetes and prediabetes in an analysis of blood. Therefore question “the safety of high-protein diets in the long term”, although it is considered that they can only be harmful for some people, especially if they are done for a short period of time. In addition, they dismantle the idea that they are better at losing weight than other conventional diets. This attribution is generally assumed, and is justified in that they have a more satiating effect than others and in that they increase energy expenditure. But, according to the new study, the scientific evidence that they are better at losing weight is, at best, weak.
The scientific evidence suggests that they are effective to reduce some size and reduce the body mass index diets that limit fat —Up to a maximum of 30% of the energy ingested, as recommended by the World Health Organization. But the literature also points to a worsening of the levels of HDL cholesterol and triglycerides, a type of fat found in the blood and that has been linked to the risk of heart disease. “This negative effect is probably determined by the type of fat and the quality of carbohydrates consumed” in this diet, says the new text.
Scientists have found evidence of not too much weight that Total cholesterol and LDL improved with the Nordic diet, that prioritizes the consumption of vegetables, fruits of the forest, grain cereals and fatty fish; The same goes for the vegetarian and the portfolio diet, It is offered precisely to control cholesterol through nutrients such as the soluble fiber of some vegetables and legumes, soy protein and foods such as nuts. Blood pressure also showed improvement in all three diets. All of them seem like good options, but whoever aspires to the best should focus on a known trip and a less known but equally interesting option.
Mediterranean and DASH, the ones that offer the most guarantees
In the field of scientific research, there are two diets that prove to be as robust. “The most consistent results were observed in studies that included dietary patterns such as those of the Mediterranean and DASH diets,” say the researchers. The Mediterranean diet win by win. “It was the only diet that demonstrated beneficial and significant effects in all the parameters analyzed, with no evidence of potential adverse effects”: weight reduction, body mass index, total cholesterol, glucose and blood pressure, as well as weak evidence of improve levels of LDL and HDL cholesterol, triglycerides, insulin and HbA1c.
DASH reported evidence of being beneficial in controlling weight and blood pressure, and slightly in the body mass index and cholesterol levels. It is not strange, considering that this diet is designed to control hypertension without taking medications (the name means nutritional approaches to stop hypertension, for its acronym in English) and is a design of the National Institutes of Health of States United). Both the DASH and the Mediterranean diet are characterized by having a high content of fruits, vegetables, fish and nuts, and scientists have linked adherence to both with a lower risk of cardiovascular events, diabetes and cancer in epidemiological studies.
Neither eat nor fast as in Prehistory
Among the most peculiar diets that have become fashionable in recent years, the Paleolithic diet stands out, which proposes eating as our ancestors of the Stone Age because the organism is not prepared to assimilate the rapid progress of modern food. That is, meat and fish when they are available, and everything you can collect from nature, from fruit to anything edible that comes from a plant. Eating raw meat (according to the image that has been left of the humans of this time) and drinking water from the river, how in Prehistory, it can make you feel good, but don’t do it because scientific works recommend it; the new work concludes that the analyzes that extol the goodness of the paleodiet are of doubtful credibility: They are usually made with very few people who are subject to too short follow-up, sometimes the results are published only when they are of interest and that there are authors with potential conflicts of interest.
The critics of the scientists also reach the famous diets of intermittent fasting, in which periods of fasting alternate with others in which one can eat whatever one wishes. Studies indicate that cutting between 15% and 40% of calories helps prevent diabetes, hypertension, cardiovascular disease and some types of cancer, and if you can’t say sharply that eating a little extends life, some What scientists are quite convinced, is because to prove it is an important logistical challenge: the new work affirms that the clinical trials that have tried to prove the validity of these promises in people have been too few and too small.
“Except for a meta-analysis that reported weak evidence on insulin reduction, all other meta-analyzes that assessed weight, lipid profile, glucose metabolism and blood pressure did not report any evidence of the superiority of intermittent energy restriction. regarding the restriction of continuous energy “. That is, according to this study, cutting the energy we eat every day would give the same result as doing it only a few days a week, or a month, and, according to the available literature, intermittent fasting would give the same result as eating A little less every day. According to one study, the positive effects of restricting energy are seen even in healthy people with a 300-calorie daily snip.
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