The long-term examination of five low-carbohydrate diets indicates that, more than quantity, it is the choice of foods that counts, which must be healthy
To lose weight, many people rely on low-fat diets carbohydratesthe so-called «low carb» because they usually ensure the best results in less time with the (more or less marked) renunciation of bread, pasta and other cereals. Since one of the problems of those who rely on these dietary regimes is the phase of maintenance of ideal weight in the following years (which tends to rise), the researchers of Harvard TH Chan School of Public Health of Boston tried to figure out if they were the types of foods chosen in the different «low carb» diets to make the difference.
They examined data from over 123,000 participants in three longitudinal studies (which examine changes over time) of English healthcare workers: the Nurses’ Health Study (NHS), the Nurses’ Health Study II (NHSII) and the Health Professionals Follow-up. up Study (HPFS). The average age of the subjects taken into consideration was 45 years and 83.8% were women. All participants were healthy, without pre-existing chronic conditions. All followed «low carb» diets with a quantity of carbohydrates equal to 40%-60% of the total daily caloric intake for a prolonged period of time.
They were further divided into five food groups: those who followed an overall low-carb diet (defined «pure low carb»); those who mainly used animal proteins and fats (a classic «keto diet»); those who favored proteins and fats of vegetal origin (“vegetable”); those who chose to consume less refined (whole) carbohydrates, more vegetable proteins and healthy fats (defined as “healthy”) and those who followed a dietary plan that included saturated fats, more animal proteins and refined grains (defined as “unhealthy”).
There have been changes monitored every 4 years up to 20 years in total. The study was published in December in the scientific journal JAMA Network Open.
People who followed the “unhealthy” diet (based on refined carbohydrates, rich in animal proteins and saturated fats) in the long term gained more weight than those who concentrated on consuming more fruits, whole grains and vegetableswith less dairy, red and processed meat, sugar, sugary drinks and sweets.
In particular, the representatives of the two extreme groups (“healthy” and “unhealthy” diets, see above and in the graph, ed) at the end of 4 years recorded an average difference of 4.5kg gained to the detriment of those who have adopted unhealthy low carb diets as their primary strategy.
The study also found that associations between increased weight and an “unhealthy” diet were more evident across individuals younger, less active and heavier at the beginning of the study.
The expert’s comment
Even though all three initial studies are “observational”, i.e. not designed to establish a cause-effect relationship, “they are prospective (therefore much more reliable than retrospective studies) and with a very high number of subjects studied”, comments Stefano ErzegovesiNutritionist and Psychiatrist and adds: «It is a false myth that carbohydrates make you gain weight and proteins make you lose weight: in the long term, It is scientifically proven that low-carb diets make you gain weight more than balanced Mediterranean dietsespecially in people who most need to lose weight (obese people).”
What can those who need to lose weight learn from the results of this research? «The strictest low carb diets (such as Keto), so to speak the classic “I only eat salad and steak”, in the long run lead to weight gain, especially if the proteins are only animal and even more so if the fats are low quality, therefore animals, therefore “saturated fats”».
What to choose? «If the carbohydrates are wholemeal and the proteins are vegetable (such as legumes) so as to get more fiber and more antioxidants, you will lose weight for longer. The optimal diet remains the “poor” Mediterranean diet, with at least half of the proteins of plant origin and a choice of good quality carbohydrates. So let’s stop worrying about “carbs yes or carbs no” and let’s focus on quality of carbohydrates: if they are of good quality – for example whole grains or durum wheat pasta cooked al dente – they can be eaten at every mealincluding dinner”, concludes the expert.
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February 4, 2024 (modified February 4, 2024 | 07:45)
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