Abordagens nutricionais para emagrecimento – parte 1

How are you, dear reader?
   Today the subject is one of the most questioned by the general public.  Despite being very technical, the purpose of this article is to explain to the general public (with or without knowledge in the health area) how our metabolism works, when it comes to gaining weight (gaining fat mass) or losing weight (losing fat mass, increasing mass  slim).

Abordagens nutricionais para emagrecer

  In this context, there are several ways to reach the same end: losing weight.

Starting by analyzing this word, “to lose weight” means “to become thin”, or else, to spend fat mass and, if possible, maintain or increase lean mass.

Lean mass can also be called “fat-free mass”, not directly representing muscle mass. Lean mass is the weight (in kg) of everything that is not fat in our body: bones, muscles, organs, blood and other fluids, food content in the digestive tract and even hair! This varies from person to person but there are average values ​​by age and gender. 

  Therefore, “losing weight” is not the same thing as “losing weight”. Because, when you lose weight, you can even gain fat mass (%), when you essentially lose fluid and muscle. Therefore, our goal is to be “thin”, like milk, that is, to have a low percentage of fat.

  That’s why “losing weight” is not necessarily good for your health. This happens especially in cases of severe food restriction, in which a low or very low caloric intake per day is ingested, causing our body to lose weight in muscle and fluid. Result: fast weight loss (up to 4kg in a week), but fast gain as well. In addition to flaccidity, hormonal and metabolic deregulation that these situations can cause in our body.

Read: Why Calorie Restriction Can Make You Fat (Blog Fat New World)

   In this way, let’s literally forget about “the soup, pineapple, sap diet”, because we already know that they will make us lose bad weight, that it will quickly return and that it will make our metabolism more resistant to future weight loss.

   There are then two most used and well-founded nutritional approaches. There are thousands of scientific articles that compare its effectiveness in the short/medium term. Are they:

Em termos de classificação uma dieta hipolípidica  ou “low-fat diet” fornece entre 10 a 15% do valor energético total em lípidos. Esta abordagem consiste no pressuposto de que as gorduras são os nutrientes que fornecem mais calorias por grama:

  • Lípidos/ gorduras: 9kcal/g
  • Proteínas: 4kcal/g
  • Glícidos/ hidratos de carbono: 4kcal/g
  • Álcool: 7kcal/g

  De facto é verdade. No entanto, atualmente sabe-se que apesar de “uma caloria ser uma caloria” sob as condições controladas de uma unidade metabólica, existem, na realidade, interrelações mais complexas no nosso organismo. Isto é, a obtenção de calorias (energia) dos nutrientes depende de vários fatores como interação entre nutrientes no alimento e entre alimentos na refeição, mastigação, absorção intestinal, ambiente hormonal, pratica desportiva, taxa metabólica, doença, medicação, etc. Pois bem, isto quer dizer que nem todos e nem sempre se obtém a mesma energia de 1g de nutriente.

   Este facto tem levado a abordagem hipolipídica a cair em desuso e tornar-se “ultrapassada”.

   As principais características destes planos alimentares são:

  • controlo das porções em gramas (ex. 150g de carne);
  • Evitar todas as gorduras (peixes gordos, carnes vermelhas, queijos, manteigas, enchidos, azeite…)
  • Modo de confeção cozido ou grelhado.
  Resultado desta abordagem em termos práticos: monotonia, incapacidade de se pesar tudo o que se come, sabores repetitivos e insípidos… desistência.
  Esta abordagem foi muito praticada até aos anos 90 pelo “boom” de mortalidade e morbilidade associado às doenças cardio e cerebrovasculares e  doenças circulatórias. Isto porque se sabia que o aumento de gordura no organismo e principalmente no sangue (colesterol, triglicéridos) predispunha a estas doenças.
   Contudo, atualmente sabe-se que a gordura corporal não é constituída por “gordura da alimentação”. Muito pelo contrário, é mais fácil para o nosso metabolismo formar gordura a partir do açúcar alimentar. E quando essa gordura se deposita na zona central, aí sim existe risco aumentado de doenças cardiovasculares.
Obesidade - per abdominal
Obesidade abdominal vs obesidade ginóide
Assim durante os anos 90 começou a ser mais comum, embora pouco aceite pela comunidade científica, uma outra abordagem nutricional: a hiperproteica, hipoglicídica.   Para além disso, avançou-se no estudo da diabetes (concentrações elevadas de açúcar do sangue), percebendo-se que o açúcar e a resistência à insulina é que tinham um papel decisivo no combate à massa gorda e assim às doenças cardiovasculares, que continuam a ser as principais causas de morte em Portugal.

This approach has been known since the 1960s. Its first “inventor” was an American cardiologist by the name of Robert Atkins who later, in 1972, published the book “The Revolutionary Diet of Dr. Atkins”, revised in 1992 as “The New Revolutionary Diet of Dr. Atkins”. This was in fact a revolution for science, in the sense that it proposed an increase in the intake of proteins and fats and a radical cut in carbohydrates (starches and sugars). The controversy has been huge to this day. After that, other “diets” emerged such as the “Hollywood Diet” – South Beach Diet – or more recently the “Princesses Diet” – Dukan Diet. How do these vary? In the contribution of carbohydrates to the total energy value (VET):

  • Diet with carbohydrate restriction “Reduced-carbohydrate diet”: between 130 to 160g of carbohydrates per day, more than 45% VET;
  • Moderate hypoglycemic diet “Low-carbohydrate diet”: between 30 to 130 g of carbohydrates per day
  • Severe hypoglycemic diet “very low-carbohydrate ketogenic (VLCK) diet”: less than 30 g of carbohydrates per day (ketosis).

In metabolic terms this approach focuses on the knowledge that glucose (sugar) is our body’s main “fuel”. In other words, if we were a machine, we would run on sugar. Fat is just an alternative fuel. So, if we want to use up this second fuel that is reserved in our cells, we have to literally “cut” it with the main fuel.

Furthermore, on the other hand, in the modern approach there is an increase in protein-rich foods. This is a noble nutrient, which means that our bodies do not preferentially use protein to produce energy or form fat. This is because proteins have a constructive function, they are “the building blocks” of our organism and therefore are spared from energetic metabolic pathways.

  Furthermore, it is known that protein has a satiating effect, prolonging the digestion time and also a catabolic effect (“fast metabolism”) by favoring the maintenance and formation of muscle! If you want to know more, read these articles from the “Fat New World” blog:

  • Influence of protein on energy consumption in humans: study

  • Ketogenic and low-carb diets for appetite control

  • High-protein diets increase satiety regardless of the number of meals

   In practice, what is done in these plans?

  • Avoid foods with carbohydrates (flour and sugar): cereals, bread, biscuits, toast, fruit, rice, potatoes, pasta, beans, etc. As well as all artificial sugars: sweets, pastries, processed foods, etc.
  • The consumption of “lean” proteins is increased: poultry and meat products, fish, shellfish, shellfish, some dairy products, egg whites, etc.
  • There is no “quantity limit” for proteins and vegetables. In other words, your plate is supposed to have a lot of fish, with vegetables, but zero potatoes.
  • The preparation is varied, avoiding sauces and fried foods.

   In this way, plans become less monotonous, more diversified and easier to comply with, as they are not so costly in terms of time needed to weigh food, more satisfying and accessible outside the home. These and other factors are in favor of short/medium-term adherence to the high-protein, hypoglycemic nutritional approach.

A parte 1 deste artigo acaba por aqui. A segunda parte irá responder a perguntas que ficaram pendentes:

  • Qual a abordagem mais eficaz a curto, médio e longo prazo?

  • Qual a abordagem que traz mais benefícios para a saúde?

  • Qual a relação destas abordagens e os hábitos alimentares a longo prazo?

  • Qual “eu” devo seguir?

 NOTA: Salienta-se que este é um artigo informativo! Não deve “sozinho” pôr em prática nenhuma restrição alimentar, pois pode acarretar alterações da sua saúde. A abordagem mais adaptada ao seu caso é individualizada e decidida por um nutricionista.

Leia já a parte 2: