Nutrition: how to lose weight? Five popular diets and what the experts think
You don't even have to finish typing "how to lose weight" into a search engine and the rest will pop up with phrases like "5kg per week", "10kg per week" or "quick and easy". .
The same goes for the words “diet” or “weight,” which are quickly followed by much-researched terms, such as traditional or fad diet names, such as “ketogenic,” “low-carb,” “soup,” “paleo,” “dukan.” ' or 'Banting'.
However, the Brazilian Ministry of Health warns: "When weight is the only focus of the intervention, the means to achieve it may move away from what are considered healthy attitudes."
So which of these methods would be effective for the 2.3 billion adults worldwide who are overweight, of whom 700 million are obese?
In terms of popular diets, cutting calories leads to body weight loss, regardless of the macronutrient amounts indicated in the recipe. Whether it is an excessive or low glycemic (carbohydrate) diet, excessive or deficient protein (protein) diet, Or excessive or minus fat (fat), I will lose weight if the calorie intake is low,” summarizes BBC News Brazil dietitian Durval Ribas Filho, president of the Brazilian Association of Dietetics (Abran).
In other words, it could be a ketogenic, Paleolithic, Ornish or Mediterranean diet: the general convergence point is that, regardless of their characteristics, they will all work to reduce body weight if food intake is generally limited. At 1200 to 1500 calories per day.
"But adherence to the system, whichever system you choose, is the most important factor," says Ribas Filho.
Is the type of diet really different or are there more or less significant differences around the same principle? Do they work for everyone or will everyone have a different answer? What happens when overweight and obesity become chronic? How do you prevent rapid weight loss from being followed by weight gain later? Can certain types of food be removed? Is it possible to eat a healthy diet without spending a lot of money?
BBC News Brazil answers these questions below based on expert analysis of many factors involved in weight loss, as well as the mechanisms of some of the most popular diets, such as the low-carb diet, the ketogenic diet, and the low-fat diet. The Paleolithic Diet.
It is important to remember that all of them must be adopted with the monitoring of a dedicated professional due to the health risks inherent in all types of diets.
“Some of these diets are related to restriction of basic food groups for the proper functioning of the organism or to an indication of excessive consumption of certain foods, which leads to an overload of certain organs, which leads to the emergence of symptoms and diseases,” explains Daniela Cerro. Vice President of the Brazilian Nutrition Association (Asbran).
"Their attachment is usually temporary, as it can lead to nutritional deficiencies and potential health risks, as well as modification of eating behavior, which may lead to potential eating behavior disorders in people with predispositions."
Types of weight loss methods and mechanisms
According to historical records, the Undertaker William Banting was the first person to develop, estimate and publish, until the 19th century, a carbohydrate-restricted diet.
In doing so, he controlled the amount of bread, potatoes, dairy products, barley, and sugar, under the direction of physician William Harvey.
Banting lost about 40 kg and 35 cm from his waist in about a year, in addition to restoring his hearing, which was damaged by weight gain, diabetes and high blood pressure.
Since then, according to specialists, most books and diets created revolve around hypoglycemia or low-carb dynamics, such as Dr. Atkins' diet, a diet created in the 1970s, which is very similar to William Banting's, published in 1863.
Along with differences in the Mediterranean diet, the vegetarian diet and the intermittent fasting strategy.
"Theoretically, these (low-carb) diets will benefit from stimulating less insulin, so there will be less metabolic stimulus for fat storage and increased fat oxidation (utilization). , nutrition expert Gleason Veloso, who specializes in applied nutrition to physical activity from the University of São Paulo (USP), according to BBC News Brazil.
But so far, there is no perfect universal diet for weight loss that will suit everyone.
In general, what characterizes them is the metabolic pathway chosen for more or less interest, glycolytic (carbohydrate), lipolytic (lipid) and proteolytic (amino acid), as well as their intensity.
Let's take a look at some of the most popular diet strategies for weight loss.
Low carb, ketogenic and paleo diet
Most diets created during the last century revolve around the dynamics of eating low carbohydrates, such as sugars, pasta, and bread.
Understand three of the most popular diets based on this principle below: the low-carb diet, the ketogenic diet, and the Paleolithic diet.
The low-carb diet and the ketogenic diet have a similar nutritional basis, but they differ mainly in the amount of carbohydrates eaten per day.
This is 60 to 130 grams of carbs per day for a low-carb diet and less than 50 grams for a ketogenic diet.
This reduced amount is necessary in a ketogenic diet until the body enters ketosis (when the body uses stored fat as an energy source for daily activities, by reducing this store).
In these methods, food consumption includes vegetables with a low glycemic index such as eggplant and zucchini, and fats and oilseeds such as walnuts, almonds, and tree nuts. Lean proteins, such as poultry, fish, and eggs.
In the case of a low-carb diet, fruits with a low glycemic index such as blackberries, raspberries, avocado and coconut.
Ribas Filho, of the Brazilian Association of Dietetics, explains that the positive point of "low-carb" (low-carb) diets is that "when we compare the percentage of basal metabolism (the minimum energy needed to maintain bodily functions in the rest) of proteins, carbohydrates and fats , what we note is that proteins are the most preferred to increase the percentage of essential metabolism.
This diet causes the body to burn fats instead of carbohydrates, through a process called "ketosis."
It is the person who spends the most energy to be metabolized, then carbohydrates and finally fats,” explains the dietitian.
This means that in order to metabolize these foods, the body must expend more energy.
On the other hand, the dietitian explains that in the hierarchy of saturated foods, proteins are the most satiating.
“If you eat an egg and a loaf of bread, you are more satisfied with an egg, even with the same amount in terms of grams.”
Furthermore, Velloso believes that "theoretically, these diets, by containing less carbohydrates, would have the benefit of stimulating less insulin, and so there would be less metabolic stimulus for fat storage and a significant increase in fat oxidation (utilization)."
But this is not always the case, and in some people, reducing carbohydrates may "reduce the intake of fats, especially saturated fats, leading to an increased risk of cardiovascular disease."
Velloso also explains that "there are no specific contraindications, but despite the recommendation by the American Diabetes Association for glycemic control, there is a word of caution for those using hypoglycemic agents, because there may be a risk of hypoglycemia if they Dosage of the drug does not cope with the low amount of carbohydrates. ”
The Paleolithic diet also brings echoes of the low-carb diet, but its goal is to consume food similar to the consumption of our ancestors, with a preference for fresh foods.
It is mainly based on fruits, vegetables, oilseeds, tubers and meat.
According to Veloso, some of the more drastic aspects of this diet encourage the consumption of raw foods, such as milk, which can pose a microbiological risk.
On the other hand, one of the positive aspects of this diet is to reduce ultra-processed products, which are generally associated with many health issues.
Regarding the side effects common on carbohydrate-restricted diets, headaches, cramps, irritability and fatigue were observed during the adaptation phase of the diet. But it can differ from person to person.
Because of all the risks associated with any diet, Mr. Cierro, of the Brazilian Nutrition Association, reinforces the recommendation that all kinds of dietary changes should be followed by dedicated professionals.
Mediterranean, vegan, low-fat, intermittent fasting
The Mediterranean diet is more balanced because it targets more goals such as long-term weight loss and a focus on heart health and longevity.
In the 1950s, it was noted that the incidence of heart disease was lower among residents of countries with Mediterranean coasts, such as Greece and Italy.
There are many variations of this dietary strategy around the world today, but all are primarily rich in plant foods, grains, olive oil, whole grains, and seafood, especially fatty fish like tuna and salmon (a source of protein and good fats). Like Omega 3).
Low consumption of red meat, which should consist of low-fat cuts, prefer skimmed dairy products, and avoid the consumption of industrial products.
It is generally associated with taking care of heart function, and it is always a bet on health advice and nutritional guides.
According to the British Health System, for example, the Mediterranean diet is very close to the government's recommendations for healthy eating.
Vegetarian diets are a way of eating that relies on a diet rich in vegetables.
"They contain a large amount of micronutrients and fiber that help to regulate the body and promote a feeling of satiety. In addition, most vegetables have a low energy density, which makes it possible to count on consuming large amounts of food, with relatively low calories. Intake, Which increases the lack of energy and therefore weight loss," explains Velloso.
On the other hand, low-fat diets require attention to the amount of fat eaten, and are therefore based on recommendations from global food guides, and nutritional recommendations for certain health conditions, such as cardiovascular disease.
“The benefit of this type of diet for weight loss is that because fat has 9 kcal/g, you cut more calories while reducing food volume less,” says Velloso.
However, specialists warn about the potential for increased consumption of simple and refined carbohydrate sources while reducing fat, as well as the risks of hormone synthesis in case of severe fat restrictions.
Fasting is viewed as a diet, a dietary strategy that severely restricts food intake or continues not to eat it completely for a specified period of hours, with many variations.
Examples: alternate day fasting (one day you eat normally, the other day you sharply reduce calories, for example by 25% and so on); time-restricted eating (fasting is practiced for a specified period of time, from 16 to 20 hours); Full day fasting (choosing one or two days - usually alternating - per week to fast completely for 24 hours).
The main goal in the case of losing weight through this strategy is to reduce calories consumed, which is difficult to compensate during meal times, allowing you to consume fewer calories per week.
But one snag is that some people may end up overcompensating for food at the time of consumption. In addition, the dietitian warns of the risks of weakness, dizziness and anxiety due to a lack of food intake.
An 8- or 12-hour fast can be adapted to daily life without much difficulty ("you finish dinner at 8 and don't eat again until 8 in the morning"), says Ribas Filho, of the Brazilian Society of Dietetics.
But it does issue an alert for pregnant women. “A pregnant woman cannot fast under any circumstances.”
According to him, studies show that if a pregnant woman fasts for more than four hours, ketone bodies are formed, which harms the psychomotor development of the child.
Veloso reminds us that no matter which method is chosen, the most important thing when considering weight loss and weight maintenance is to respect the patient's diet and each person's individual needs, such as socioeconomic background and food preferences. Culture, religion, routine, metabolic risks and comorbidities.
Why are people overweight or obese?
Basically, people generally gain weight when they consume more calories than they expend, and conversely, they lose weight when they consume less than they expend.
Over time, the imbalance between higher intake and lower energy intake leads to weight gain or obesity.
The World Health Organization defines overweight and obesity as abnormal or excessive fat accumulation, which poses a health risk. In the case of COVID-19, for example, the increase in body fat increases the entry points of the coronavirus, which stays longer in the bodies of obese patients.
Fat, in general, is how we store that extra energy that isn't being expended.
But, as explained above, gaining or losing weight is not just a matter of increasing or decreasing calories eaten each day.
Complex and multifactorial obesity is a chronic disease and a serious public health problem, as it is a risk factor for other diseases, such as hypertension, diabetes and cardiovascular disease.
The causes of overweight include several factors, such as genetics, environment, drug use, lack of physical activity, mental health and consumption habits - the population benefits, for example, from a large supply of high-calorie, ultra-processed and cheap foods.
According to Veloso, the relationship between socioeconomic vulnerability and obesity risk is now a topic of great debate.
“The nuances of all social classes in access to safe and high-quality food and strategies to combat obesity, including gender and access to information, must be considered, taking into account the nuances of all social classes, with greater risks for those with financial and educational opportunities Less for safe access and consumption of food and information.”
The dietitian also explains that weight gain and weight loss also involve the regulation of a patient's hunger and satiety signals, which scientists have not yet fully understood, and that psychological factors, socioeconomic issues and even inflammation in the body can interfere with this. , for example.
How diet can affect your mental health
Ribas Filho remembers that satiety and weight gain are also related to eating speed. This happens, he says, because some people eat so quickly that the body doesn't have time to release substances that signal the brain to stop eating and feel full.
In addition, the UK healthcare system highlights the impact of underlying conditions that can contribute to weight gain, such as hypothyroidism, and medications such as some corticosteroids.
All of these factors lead to nearly two-thirds of Brazilians being overweight, the National Health Survey (PNS) estimated in 2019, a rate that has doubled in 17 years.
Observational research on chronic disease risk and protective factors through a telephone survey (Vigitel), from the same year, highlighted that more than half of the participants were overweight (BMI equal to or greater than 25) and about 20% were obese (BMI equal to or greater than 30).
BMI is the body mass index, which is a general measure that categorizes overweight and obesity. It is calculated by dividing the weight in kilograms by the square of the height in metres.
This reference is used in the calculations of adults of all ages in an approximate manner and is not tax or absolute.
A 30-year-old man who is 1.70 meters tall, for example, will have a normal BMI if he weighs between 53.5 kg and 72 kg, is overweight if he weighs between 72 kg and 86.7 kg, and is obese excessive.
But this indicator is only one of the elements used in the definition of a diet by a trained professional.
Ribas Filho, of the Brazilian Society of Dietetics, explains that obesity, because it is a complex disease like diabetes, is being introduced into the chronic disease treatment hierarchy.
That is, there are 4 possible stages (which can vary): first diet and physical activity, then cognitive and behavioral changes, then the use of bariatric drugs, and finally bariatric surgery.
Why do so many people lose weight, but later return to their initial level?
According to Mr. Siero, of the Brazilian Nutrition Association, understanding the factors associated with excess weight is essential to the success of both weight loss and weight maintenance.
"When we address these individual needs, we take into account many factors that need to be considered when planning meals. We need to understand that we are individuals with different genes, different dates, different ages, and different responses."
So why do some people find it difficult to lose weight or maintain the weight they have achieved while dieting? There are also several points related to the so-called accordion effect.
According to Velloso, one of them is the body's own reaction to a lack of calories, meaning the fact that one is eating fewer calories than one expends.
“When we lose weight and body fat, the alert triggers a response so that fat stores are restored. The less fat, the more leptin, a hormone secreted by adipose tissue, which is a signal of satiety, is weak. A signal is sent indicating that it is necessary Consuming more calories so that there is a normalization of body fat and an increase in the hormone leptin. "
Thus, weight regain is primarily associated with increased hunger and satiety (or better, the lack of them).
Ribas Filho explains that the metabolic characteristics of people who are overweight or obese differ after weight loss.
"It's as if it was cavernous time, when man used to conserve his energy because there was no food available every day. As if today, after this process of biological evolution, the organism would say 'I don't don't want to lose weight and what to do after losing weight goes down' The metabolic rate at rest spends less and the activity of the autonomic sympathetic nervous system decreases.
But it's not just about physiological and metabolic factors. Mr. Veloso also points out not sticking to the diet plan outlined by a medical professional, as with diets.
This happens for several reasons, one of which is the degree of dietary restriction.
Cierro from the Brazilian Dietetic Association reminds us that when weight loss occurs through restrictions on food groups and essential nutrients to maintain the body, there can be muscle loss (lean body mass), dehydration and decreased metabolism (energy expenditure).
Furthermore, mood can also be affected by dietary restrictions, as well as hormonal changes and emotional factors.
Thus, when this person stops the diet and resumes his eating habits, "the body tends to store food as fat, because it realizes that the state of scarcity can return (again in the future)".
Therefore, Velloso advocates that people should be made aware of the importance of continuing treatments for weight gain and obesity and that this cycle of gain and loss is to be expected.
He explains that for obese patients, whose BMI is over 30, losing weight is more difficult. This is because their metabolic properties after weight loss contradict themselves.
And then there may be weight gain or the famous accordion effect. But this in relation to obesity is not the case for patients who want to lose, for example, up to 5 kilograms.
"Numerous studies claim that non-pharmacological treatment of obesity has many long-term limitations," Dorval Ribas explains.
“On average after 6 months to a year it varies from work to science work, reduced calorie diet, cognitive behavioral change and with physical activity unfortunately change in body weight in percentage terms returns to previous levels. There was a drop in weight, but then there was a limitation because the person himself was finding it difficult to keep up.”
Studies show that even small changes in eating habits and losses as modest as 5% of body weight, significantly increase life expectancy and promote noticeable improvements.
Research published in the New England Journal of Medicine has shown that, in this way, it is possible to reduce death rates from cardiovascular and other diseases by up to 17%.
Weight gain in children and adolescents
Determining overweight and obesity in children and adolescents is challenging because these young adults are still developing.
The World Health Organization suggests the use of Child Growth Charts, which measure, track and evaluate the growth of children and young adults aged 0-19.
But it is important that they are followed by health professionals who specialize in this age group.
“Each age group between childhood and adolescence is directly related to the stages of body growth and development, and thus nutritional needs differ. The eating behavior of children and adolescents, as well as in adults, varies at different stages of life, taking into account the level of physical activity and lifestyle, under the influence of social, economic and cultural issues and emotional, among others,” explains Siero, of the Brazilian Association of Nutrition.
Velloso notes that "calorie, nutrient or food group restrictions should only occur in children and adolescents when there is a clear indication of weight gain or other disease."
It is estimated that more than 6 million children are overweight in Brazil, and 3 million have become obese.
Among children aged 5-9 years followed by the Unified Health System (SUS), 13.2% are obese and 28% are overweight.
As for children under the age of five, they are 15% overweight and 7% obese.
As in adults, several factors play a role. According to the World Health Organization, the Covid-19 epidemic, for example, has exacerbated and affected the diet of minors, and currently about 340 million adolescents are overweight or obese.
During the pandemic, Brazil also experienced widespread hunger (which is not necessarily the opposite of obesity), with a quarter of Brazil's population experiencing severe food shortages.
Dr. Ribas Filho also points to the relationship between weight gain and epigenetic factors, in which gene expression is altered without changing the DNA itself - small chemical tags are added or removed from the genetic code in response to changes in the environment in which it is located. We live.
“Epigenetics shows that chronic diseases begin at the intrauterine level. For example, if the baby’s mother weighs more than 24 kg or more during pregnancy, or if the child is born with more than 4 kg, or less than 2.5 kg, then it is possible that the child has of obesity,” explains the dietitian.
According to him, children who are born with a low birth weight can develop survival mechanisms to provide energy throughout their lives.
Finally, Velloso cites the impact of the sedentary lifestyle and dietary habits of the family as a whole, particularly the consumption of ultra-processed foods dictated by marketing and hypersalivation (a combination high in fat, sugar and/or sodium that makes it difficult to stop eating such highly-cooked foods, such as pizza, fried foods, and sweets). ).