INTRODUCTION

Bariatric surgery (BS) is a procedure indicated for the treatment of severe obesity, when patients do not respond to conventional treatment, which involves changes in lifestyle and drug therapy¹. By reducing gastric and absorptive capacity, presenting a low risk of complications and being effective in reducing excess weight, Roux-en-Y Gastric Bypass (RYGB) is a technique considered the gold standard², corresponding to the main BS performed in Brazil³. The weight loss induced by BS can be divided into phases, in which the first six months after surgery, the short-term, is characterized by a marked weight loss⁴. The weight loss has generally reported as percentage of initial weight loss (%TWL)⁵. %TWL is a desirable method because its accuracy, and it is less influenced by confounding anthropometric factors, such as initial BMI^5,6.

However, the treatment of severe obesity does not depend exclusively on the surgical procedure. Diet is a key factor, and its quality can compromise the success of the treatment⁷. In the early weeks of the postoperative period, patients submitted to BS present changes in food intake, such as the ingestion of a liquid diet in small volumes, which can hinder an adequate intake of calories and nutrients, as well as food from the different groups^7,8. It is very common to observe after BS, the development of food intolerances and/or aversions, which may increase the risk for the appearance of nutritional deficiencies⁹. In general, at this stage, the diet is characterized by a low variety of foods, insufficient consumption of proteins and micronutrients^10,11.

One study showed that the dietary intake of vitamin C, B12, zinc and iron, of 42 individuals submitted to RYGB reduced significantly (p<0.05) in the first month after surgery, remaining low until the 6th month after bariatric surgery. Concomitantly, plasma levels of hemoglobin, vitamin B12 and ferritin decreased significantly (p<0.05) during this period¹². Another study also found an inadequate consumption of several vitamins and minerals in short-term after BS¹³. Although the studies carried out a quantitative assessment of ingested nutrients, a qualitative analysis of the food consumption of the different groups, which would allow a complementary assessment of the diet of these individuals, has not been carried out.

The quality of a diet can be evaluated by several methodologies¹⁴. The Healthy Eating Index (HEI) allows the analysis of compliance with the intake of food groups, yielding a total and separated components score that reveal a pattern of dietary intake. HEI can be applied to evaluation of individuals and groups, being able to support dietary interventions¹⁵, although studies that evaluate the diet quality by HEI during follow-up of RYGB patients are scarcely described. Thus, this study aimed to evaluate weight loss, body parameters and diet quality during the short-term (6 months) follow-up of subjects undergoing RYGB.

MATERIAL AND METHODS

RESULTS

In the present study, there was a predominance of female participants (89%, n=15), with a mean age of 39.7 ± 8.0 years. Regarding the degree of obesity, 71% (n=14) had grade III obesity and 29% (n=4) grade II obesity. Subjects were assessed, on average, 28.1 ± 24.3 days (T0) before surgery, 77.7 ± 23.9 days (T1) and 214.9 ± 90.1 days (T2) after surgery.

Table 2 describes the body parameters of the participants in the three moments. %TWL increased significantly between T1 and T2 (p<0.001). A significant reduction in weight, BMI, WC, FFM and FM was observed throughout the moments (p<0.001), with significantly different values between each moment (p<0.05).

The subjects’ caloric and macronutrient consumption are described in Table 3. A significant reduction in the consumption of total calories is observed throughout the evaluated periods, with lower values at T1 (p<0.05). However, kilocalorie consumption relative to body weight increased significantly over time (p=0.006), with higher values observed at T2. Lower values of total fat intake were observed at T1. No significant changes were observed in carbohydrate, protein and saturated fat consumption across time points (p>0.05).

Regarding the diet quality measured by the HEI, the diet was classified as “poor quality” at three times. With regard to the HEI components, no significant changes were observed over time in any of the items (p>0.05) (Table 4).

DISCUSSION

In this study, subjects showed a low diet quality during all evaluated moments, despite total weight loss and reduction of body parameters.

The low quality of the diet observed can be explained, in part, by the food restriction induced by the RYGB itself. In this procedure, stomach is reduced to a capacity of between 20 and 30 ml²², which makes adequate food intake difficult¹⁰. In addition, it is common to observe in bariatric patients the presence of symptoms such as nausea, vomiting, diarrhea or intestinal constipation and complications such as dumping syndrome, factors that can also compromise adequate food intake²³.

The increase in caloric intake relative to body weight (kcal/kg) six months after the BS is related to the weight loss. Although an increase in caloric intake relative to body weight was observed, the consumption of total daily calories remained low at all times evaluated, which is also expected, due to the reduction in gastric volume imposed by the surgery²².

Regarding the consumption of foods from the different groups, it is worth mentioning a higher consumption of foods from the total fat, saturated fat and cholesterol groups throughout the follow-up period, which is a reflection of previously existing eating habits, as observed in the food recall (data not shown). These data may indicate poor adherence to the nutritional counseling received by patients throughout the perioperative follow-up. It can be observed that the food variety is extremely reduced and most patients are intolerant to some food groups.

With regard to carbohydrate consumption, it was observed an intake above the recommendation of 50g in the immediate postoperative period, with progression to 130g/day²⁴. The individuals in the present study had a higher consumption of simple carbohydrates, which can trigger intestinal disorders, dumping syndrome and impair adequate glycemic control^22,23. In addition, the higher consumption of simple carbohydrates confirms the presence of inadequate eating habits even after the surgical procedure. Evidence is conflicting regarding the relationship between binge eating and simple carbohydrate consumption in bariatric patients²⁵, although in many cases this behavior tends to improve after surgery²⁶.

In this study, there was a low daily protein intake by subjects, which corroborates the results of other studies^27,28. In addition to reduced gastric capacity, it is also common to observe an aversion to some protein foods, which difficult the ingestion of protein-based solid foods, especially during the first months after surgery²⁸. This low dietary protein ingestion could result in a higher loss of FFM than expected, as verified in the present study. An adequate protein consumption avoids the abrupt reduction of FFM and acts in the maintenance of muscle strength⁸. In this context, protein supplementation might be recommended in order to prevent protein malnutrition and loss of FFM²⁹. Bertoni et al.,³⁰ observed that the intake of animal proteins by patients submitted to BS was below the proposed recommendation of 60 to 80 g/day or 1.0 to 1.5 g/kg of ideal weight g/day in the first three months after the BS. The substantial loss of FFM in patients submitted to BS is related to unfavorable clinical and nutritional evolution and worse quality of life for patients³¹. In this study, a low consumption of the milk and dairy products group was also reported. Bariatric patients may develop lactose intolerance and gastrointestinal symptoms which could make them avoid these foods²³.

With regard to lipids consumption, the subjects had a low consumption during all evaluated moments, when compared to the recommendation of Mechanick³², which suggests an intake between 20 and 35% of the total caloric value of the diet, with emphasis on the consumption of polyunsaturated fats. However, despite the fact that the consumption of total lipids was below the recommendation, there was a higher score in HEI index from saturated fat at all three times, which can be explained by the greater consumption of processed and high energy density foods observed in the food recall before and after BS (data not shown). In addition, almost half of the HEI score was related to the consumption of total fat, saturated fat and cholesterol. These findings suggest the existence and maintenance of an inadequate eating pattern during the follow-up. Furthermore, it is not uncommon to observe patients that believe that the BS itself completely treated the severe obesity, and often fail to understand that improvements in the quality of the diet are necessary for the success of treatment in medium and long-terms.

The consumption of fruits and vegetables evaluated in this study was also low, which may be related to the fiber content of these foods, which is normally not well tolerated by individuals submitted to BS¹¹. Other studies report that a nutritionally poor diet, justified by the low consumption of fruits and vegetables, can lead to micronutrient deficiencies^13,14. It should be noted that some patients lose adherence to treatment, tend to miss follow-up appointments, become more permissive with regard to the intake of foods of low nutritional value and neglect nutritional counselling, contributing even more so for an unbalanced diet.

It is evident that RYGB is an efficient therapeutic option for the treatment of severe obesity². In the present study, %TWL at two and six months after RYGB in accordance with previous observations^33,34, and up to 20%, which is considerable adequate in the short-term period³⁵. In an individual analysis, only 2 subjects (11%) showed %TWL above 20% (17.2% and 19.6%, respectively). %TWL has been used as a primarily parameter to express BS outcome, been recommended by the American Society for Metabolic and Bariatric Surgery to report weight loss results in BS studies⁵. Moreover, a significant reduction in anthropometric parameters and body composition was also observed. Although expected, weight loss should be accompanied by maximum preservation of fat-free mass, and the low diet quality observed might explain, in part, the significative loss of FFM of subjects during the follow-up, and could compromise the success of the treatment in the long-term³¹. This data ratifies the need and relevance for dietary counseling, with a focus on nutritional education during all period of follow-up, including before the RYGB. Although RYGB reduces energy intake and, therefore, body weight, the procedure can result in unbalanced diets and inadequate intake of macronutrients and micronutrients^10-12.

The study has some limitations. The moments in which the evaluations were carried out depended on the presence of the subjects in the consultations previously scheduled by the BS program, which difficult to evaluate at the defined moments. Although the sample was hospital-based, the small size was due to the short period of invitation (5 months) and the number of subjects excluded (n=9) due to the absence of at least one R24H within the three moments. This non-probabilistic sample may have affected the statistical power of some analyses, making it difficult to generalize of results and limiting the interpretation of the results to the evaluated sample. The criteria established by the Program for selecting RYGB, such as age (older patients), presence of gastric reflux and large number of associate comorbidities, minimize potential selection bias towards patients with other clinical conditions that might affect the results. The HEI evaluates the number of servings consumed during the day^20,21, and the caloric deficit throughout the perioperative period can compromise an adequate food intake of different groups, resulting in a low score. In addition, the HEI does not take into account the consumption of micronutrients, which only allows an indirect assessment of their consumption.

CONCLUSION

In the present study, subjects showed an adequate weight loss and a reduction of body parameters, although a poor diet quality was observed, indicating the maintenance of inadequate eating habits during the follow-up, including a low consumption of fruits and vegetables and the food sources of complex carbohydrates and proteins. The HEI could be useful for predicting possible nutritional deficiencies and for early nutritional intervention in patients undergoing RYGB.