Low-carb or low-fat?
Carb-free and fat-free diets were equally effective
Elizaveta Ivtushok, N+1
Diets low in both fat and carbohydrates are about equally useful in the fight against excess weight. This was found out by a group of American scientists who prescribed two different diets to two groups of people with a high body mass index. An article published in the Journal of the American Medical Association reports that the effectiveness of the diet also did not depend on the pattern of the genotype responsible for metabolism and insulin secretion. (A detailed summary of the results of the work can be read in the Stanford University School of Medicine Low-fat or low-carb? It's a draw, study finds – VM.)
Overweight people are at risk of developing many diseases, including obesity, type II diabetes and diseases of the cardiovascular system. Moreover, excess weight also affects the quality of daily life. As the most common and proven methods of losing weight, people use physical activity or a change in eating behavior. The diet is usually aimed not only at increasing the difference between calories consumed and calories spent, but also at accelerating metabolism – one of the key links in the process of weight loss and retention.
There is no single universal diet that can help every person who wants to get rid of excess weight. The effectiveness of the two most popular types of diets – carb–free and fat-free - is determined, for example, by phenotypic differences in the human body: a group of scientists from the Stanford School of Medicine, with the participation of Christopher Gardner, found out that the effectiveness of two types of diets is associated with single-nucleotide polymorphisms of genes responsible for carbohydrate and fat metabolism: PPARG, ADRB2 and FABP2. Scientists also note the role of regulation of insulin secretion (its release in response to an increase in blood glucose levels) in determining the effectiveness of the diet.
All currently existing studies of the biological effectiveness of two different diets, however, have a number of limitations. For example, in the work mentioned above to study the role of phenotypic differences responsible for metabolism, only women were considered. Now the same group of scientists decided to test the difference in the benefits of the two diets and its dependence on the genotype and individual insulin secretion on a larger and more diverse sample. Their experiment involved 609 people aged 18 to 50 years with a body mass index from 28 to 40: scientists divided them into two groups and prescribed a diet – carb–free or fat-free - for one year (diets did not differ significantly in the number of calories consumed daily). In addition, the researchers also collected information about the gender, age, education, race of the participants, waist circumference, the presence of various diseases or contraindications to diet changes, as well as their metabolic and glucose levels. These data were then taken into account when analyzing the results.
The diet was prescribed to the participants randomly: in each of the two groups, thus, both people with high or low metabolism of fats or carbohydrates, and with high or low levels of insulin secretion were included. A year later, participants from the carb–free group lost, on average, six kilograms, and from the fat-free group - 5.3 kilograms. The difference in weight loss between the groups was insignificant. Moreover, the scientists found that neither the genotype determining the efficiency of fat or carbohydrate metabolism (p= 0.2) nor the initial level of insulin secretion (p= 0.47) affected the effectiveness of the diet.
The conducted research has a number of limitations, the main of which is a fairly generalized sample: all participants, for example, had access to the purchase of high-quality food. Despite this, scientists have come to the conclusion that the effectiveness of a certain type of diet is not determined genetically (at least with regard to differences in the metabolism of a certain type of substances) and does not depend on insulin secretion: thus, the choice of a certain type of diet cannot be based on the analysis of these parameters.
One of the factors influencing the appearance of excess weight is considered to be a late meal, but this belief, however, does not take into account the individual daily routine of people. But taking into account circadian rhythms (individual changes in the body associated with the change of day and night) is a much more accurate indicator.
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