The study compared and established differences between nutrient composition and the meal patterns of obese and eutrophic students. Between the groups, there were no differences in total energy and the amount of macronutrients consumed, except for the intake of dietary fiber, which was higher in the eutrophic group, indicating differences in dietary pattern.
Although the benefits of fiber are already a consensus, the role of fiber in the regulation of body weight is not highly valued, focusing more on the effects of energy and fat content in a diet. According to Slavin et al
], this situation occurs because when the diet is low in fiber, it is usually high in calories and fat, therefore the effects of fiber can be masked. Despite the fact the amount of calories have become the focus of attention, some studies have found that nutritional balance is the predominant factor for obesity prevention [11
Several studies have found associations between dietary fiber and anthropometric measures [14
]. There are several mechanisms by which dietary fiber may regulate body weight, such as intrinsic effects (chewing and palatability), effects of the colon (production of short chain fatty acids) and hormonal effects (decreased insulin and increased Cholecystokinin) [20
Among these mechanisms, the increase in the intestinal transit was what could have mostly contributed to the regulation of body weight in this present study, considering that high intakes of dietary fiber are associated with increased fecal loss of energy, fat and nitrogen [22
]. Also, there were no differences in energy intake between the groups, showing that the fiber did not have any influence in satiety.
Beans were the main food that influenced the amount of dietary fiber. It is believed that dried beans were more consumed because they last longer after the purchase. Besides, they have a historical importance in the Brazilian nutrition, being responsible for nutritional survival of most Brazilians [23
In addition to the high protein content, beans have high amounts of soluble fiber, soluble vitamins and minerals. Considering these qualities, some countries are specifying the amount of daily servings of dried beans to be consumed by the population [24
] and studies have confirmed that the intake of beans increases the quality of the diet, [17
] while decreasing the amount of saturated fat and total fat [26
In this study, it was determined that the higher the intake of beans, the higher the amount of fiber and iron and the lower the proportion of fat in the diet. This lower proportion of fat was evident in the eutrophic group. In this group, the higher intake of beans may have contributed to the lower intake of other energy-dense food, high in fat.
In the eutrophic group, a better correlation was verified between beans and fiber was verified when compared to the obese group, perhaps because in the third tertile of S. beans the eutrophic group had a higher intake of fiber. In some studies, the consumption of beans has influenced the weight loss of individuals [18
It is presumed that the children who did not consume beans replaced a family meal with food that presented low fiber content but similar energy density. Foods that have the same amount of total energy but different amounts of fiber can exert distinct effects on body weight regulation [30
This substitution can be confirmed by a higher adequacy in the consumption of vitamin A among obese children. It is assumed that this greater amount is related to increased intake of processed foods (e.g., cookies, chocolate powder) whose target are children. They are often enriched with vitamins and minerals, but hide high contents of fat, sugar and sodium.
Regarding the fruits, worrying results were found due to the low consumption. Most students did not consume fruits. The children in this study come from low income families and usually, in this situation, fruits are bought only once a month. The eutrophic group showed stronger correlation between the consumption of fruits and fiber compared to the obese group. This difference may be due to the different types of fruits consumed. In the eutrophic group, apples were more consumed than in the obese group. The pectin, which is the main fiber of this fruit, seems to benefit the weight loss [15
Also in the eutrophic group, the tangerine was the favorite citrus fruit and according to the Brazilian nutritional database, it has a better source of fiber when compared to orange [31
]. In general, calcium intake was below the recommended AI, being this is a reflection of low milk consumption, which has been reported in some studies [9
During the family meal, the intake of rice with beans is traditional, but this dietary pattern is changing. The consumption of beans is decreasing, especially among young people [33
]. In this present study, the low consumption of this legume and other vegetables influenced the large inadequacy of fiber intake in the groups. The urbanization favors this decline, once it contributes to the short time to prepare a homemade meal and moreover, the fast foods have more appeal due to the better palatability found in fat and sugar [34
]. This preference for sweets and fat -energy dense foods over grains, legumes and vegetables is not restricted to Brazilian children; other countries are experiencing the same situation [36
]. Recent reviews have shown association between skipping meals and an increased overweight and obesity risk in children [38
], with an emphasis on low consumption of breakfast [39
]. Increased meal frequency not only avoids high-fat, energy-dense foods and soft drinks consumption but also reduces postprandial metabolic and endocrine responses due to nutrient consumption, with lower insulin secretion [38
Finally, although the influence of energy intake in weight gain was not verified, underreport and forgetfulness cannot be ignored. Children, especially obese, may be embarrassed to report the "unhealthy" food and children who replace meals with many snacks during the day may not be aware of all the food that is being consumed, underestimating the total energy of the diet. Considering the short time parents had to take part in this study, we had some limitations with the small sample size. However, we believe that this study showed some interesting results that should be investigated with a bigger sample size.