Recommended Levels of Carbohydrate after Bariatric Surgery

by Silvia Leite Faria, MSc, RD; Orlando Pereira Faria, MD;  Mariane de Almeida Cardeal; Heloísa Rodriguez de Gouvêa; Cynthia Buffington, PhD; and Margaret Furtado, MSc, RD

Silvia Leite Faria, MSc, RD; Mariane de Almeida Cardeal; and Heloísa Rodriguez de Gouvêa are nutritionists at Gastrocirurgia de Brasília, Brasília, Brazil. Orlando Pereira Faria is also from Gastrocirurgia de Brasília. Margaret Furtado is from University of Maryland Medical Center- Bariatric Surgery Program, Baltimore, Maryland. Cynthia Buffington is from Metabolic Medicine and Surgery Institute- Florida Hospital Celebration Health, Celebration, Florida.

FUNDING: No funding was provided.

DISCLOSURES: Ms. Faria reports no conflicts of interest relevant to the content of this article.

ABSTRACT
Background: Exact carbohydrate levels needed for the bariatric patient population have not yet been defined. The aim of this study was to correlate carbohydrate intake to percent excess weight loss for the bariatric patient population based on a cross-sectional study. The author also aimed to review the related literature. Materials and Methods: A cross-sectional study was conducted, along with a review of the literature, about patients who underwent Roux-en-Y gastric bypass at least 1 year previously. Patients had their percentage of excess weight loss calculated and energy intake was examined based on data collected with a four-day food recall. Patients were divided into two groups: 1) patients who consumed 130g/day or more of carbohydrates and 2) patients who consumed less than 130g/day of carbohydrates. Limitations: The literature review was limited to papers published since 1993. Results: Patients who consumed 130g/day or more of carbohydrates presented a lower percent excess weight loss than the other group (p= 0.038). In the review of the literature, the author found that six months after surgery patients can ingest about 850kcal/day of carbohydrates, 30 percent being ingested as lipids. A protein diet with at least 60g/day is needed. On this basis, patients should consume about 90g/day of carbohydrates. After the first postoperative year, energy intake is about 1,300kcal/day and protein consumption should be increased. We can, therefore, establish nearly 130g/day of carbohydrates (40% of their energy intake) Conclusions: Based on these studies, the author recommends that 90g/day is adequate for patients who are six months post Roux-en-Y gastric bypass and less than 130g/day is adequate for patients who are one year or more post surgery. The author concludes that maintaining carbohydrate consumption to moderate quantities and adequate protein intake seems to be fundamental to ensure the benefits from bariatric surgery.

Bariatric Times. 2013;10(3):16–21.

Introduction
Nutritional guidance after bariatric surgery is aimed at modifying eating habits and, as such, is crucial for obtaining success of the surgery.[1] The literature shows that nutritional support in the postoperative stage includes a negative energy balance during the weight loss period[2] and dietary control to maintain weight in the long term, and contributes to patients’ general well being.[3–5]

In 2008, the Committee of the American Society for Metabolic and Bariatric Surgery published the Allied Health Nutritional Guidelines for the Surgical Weight Loss Patient.[6] Prior to this publication, there were no standard guidelines to serve as a basis for nutritional recommendations given to bariatric patients. For this reason, the document brought some degree of standardization to the postoperative food intake practices. However, a wide variation among bariatric centers regarding the structure and content of diets for this population remains, most likely because of a lack of studies attesting to the adequacy of macronutrients for such individuals.[7] The aim of this study was to compile the available data to elaborate upon the carbohydrate (CHO) requirements for the bariatric population.

In speaking of CHO requirements, a clear understanding of caloric intake, macronutrient distribution and protein requirements among the bariatric population is fundamental. In this way, the aim of this study was to correlate carbohydrate intake to percentage excess weight loss (%EWL) for this population, based on a cross-sectional study, and to review the related literature.

Methodology
A cross-sectional study of patients and a review of the available literature was carried out aimed at suggesting a recommendation of CHO requirements for the bariatric population.

The cross-sectional study involved patients who underwent Roux-en-Y gastric bypass (RYGB) procedure at the Gastrocirurgia de Brasília clinic, Brazil, thus forming a convenience sample. Follow-up studies of these patients were carried out by the nutritional service of our clinic between 2003 and 2006. The research subjects were selected based on the following inclusion criteria: 1) each patient underwent RYGB, 2) all surgeries were performed by the same surgeon, 3) all patients were 16 to 65 years of age; 4) all patients had undergone surgery at least one year prior to the start of the study, and 5) all patients had periodic medical and nutritional follow up appointments (minimum of twice a year). The exclusion criteria were as follows: 1) patients who worked in the area of nutrition or who had studied nutrition, 2) patients with psychiatric disease (e.g., depression, phobias) requiring psychotropic treatment, and 3) patients with bulimia and/or anorexia. The research was approved by the Research Ethics Committee of the University of Brasília’s Health Sciences Faculty, filed under no. 052/2002.

Patients had their weights and heights measured by the same nutritionist. Body weight was measured after overnight fasting using a digital scale (Filizola®, São Paulo, Brazil) with a maximum capacity of 300kg and a sensitivity of 100g. Height was measured with a wall stadiometer with 5mm sensitivity. The study assessed body mass index (BMI) values and the percentage of excess weight loss (%EWL) with the ideal weight calculated based on values taken from the Metropolitan Life Foundation Table 8.[8] Energy intake was investigated based on data collected using a four-day food intake recall. We used a nutrition software application Nutrisurvey, an English translation of EBISpro, Germany,[9] to assess the mean daily caloric intake, the mean daily protein intake in grams, and percentage of total energy intake (TEI). The mean daily lipid intake and the mean daily carbohydrate intake were assessed in grams and as a percentage of TEI.
We used the recommendation of 130g/day as a reference as found in the Dietary Reference Intakes (DRI)[10] and recommendations of the American Diabetes Association (ADA).[11] Subjects were divided into two groups: 1) patients who consumed 130g/day or more of CHO and 2) patients who consumed less than 130g/day.
The program SAS 9.2 (SAS Institute Inc., Cary, North Carolina) was used for statistical analyses. To compare the various measures taken in the two groups we used a model of analysis of variance, with adjustment for age, sex, pre-surgery BMI, time since surgery, protein intake, and fat intake. In all analyses, the significance level was 5 percent.

Limitations. The literature review was limited to papers in English published since 1993 and was based on searches using the following databases: Medline, PubMed, Lilacs, and Cochrane. The keywords used in the electronic search included: “carbohydrate requirements,” “bariatric surgery,” “weight loss,” and “dietary carbohydrate recommendations”.

Results
Cross-sectional study. Of the 100 patients assessed, only 75 met the inclusion criteria. Most of the patients were women (80%). The average age was 36.8±10.7 years (range 19–64 years). Patients had undergone surgery 23±10.3 months earlier, on average. Anthropometric and demographic variables for all the samples and differences between groups are summarized in Table 1. Average age, time after surgery, and pre-operative BMI did not show significant differences in the groups. The study sample had an average preoperative BMI value of 43±5.5kg/m2 and a postsurgical BMI value of 29.8±4.6kg/m[2]. Average %EWL after surgery was of 67.5±18.8%. The average energy intake (EI) and the mean protein intake of total population was 1,475±546kcal and was 73.4±30.9g, respectively. The consumption of CHO in the group of patients who consumed 130g/day or more of CHO was 201.1 (±50.7) and 103 (±20.7 [(p<0.0001]) in the group of patients whom consumed less than 130g/day (Table 2). Using a model of analysis of variance with adjustment for age, sex, pre-surgery BMI, time since surgery, protein intake, and fat intake, we found that patients who consumed 130g/day or more of CHO presented a lower %EWL than the group of patients who consumed less than 130g/day (p=0.0386 [Table 3 and Figure 1]).

Literature review
We found 40 relevant studies for our review of the literature, eight of which were excluded for lack of information relevant to the bariatric population. Of the remaining 42 studies, five were literature reviews and 16 were open clinical essays, among which two were randomized studies, two meta-analyses, two transversal studies, and seven presented guidelines, four of which were related to the bariatric population and three to the general population.

Caloric intake. Caloric intake among the bariatric population should be analyzed before CHO requirements are established. A “normal” progression of caloric intake occurs after surgery. Patients submitted to RYGB and other restrictive procedures present a lower capacity of food intake.12 Studies show that patients in the first six months postoperative experience a sharp drop in caloric intake in relation to the pre-operative phase, consuming a diet with a value ranging between 850kcal/day[12,13] and 1,000kcal/day.[14] Between six and 12 months postoperative, there is less of an increase in patients caloric intake. One year after surgery, caloric intake appears to stabilize, showing only minor variations in later years, reaching values between 1,100 and 1,400kcal/day.[12,15] One study[16] showed that four years postoperative, patients reached levels of 2,000kcal/day. Thus, in the first three years following surgery, it can be seen that bariatric patients consuming between 800 and 1,800kcal/day are following a low-calorie diet as defined by Tsai et al.[17] Because the literature indicates that the bariatric population can increase their caloric intake over time, dietary control is important to prevent weight regain.[18] In establishing CHO requirements, attention should be given to this evolution in the quantity of food tolerated by the patient.

Distribution of macronutrients. Literature related to eating habits among bariatric patients has shown, in general, that the percentage of macronutrient participation in TEI remains constant throughout the postoperative phases, ranging from 45 to 50 percent and from 31 to 33 percent for CHO and fat, respectively.[12–14] These percentages are within limits recommended for adults by the Institute of Medicine.[10] In Table 4, we present a list of macronutrients consumed by patients in the first six months postoperatively. Table 5 shows the consumption of the same macronutrients during the period from 12 months or more postoperatively.

Protein intake concerns. Protein intake is critical after surgery and must be included in the patient’s postoperative diet.[3] Since the stomach pouch can only hold a limited quantity of food after a restrictive bariatric procedure, priorities need to be set. To maintain good postoperative health and strength, a high-protein diet, reaching intake levels from 60 to 120g after surgery, is needed.[1,3] Protein-rich foods should be eaten first and in recommended amounts.[1]

In studies, protein participation shows levels of about 20 percent of TEI.[12,14] It is worth noting, however, that bariatric patients have some difficulty in meeting the recommended levels for protein.[13,19] For instance, Andreu et al[19] showed that among 101 consecutive patients undergoing RYGB or laparoscopic sleeve gastrectomy, protein intake less than 60g/day was present in 45, 35, and 37 percent of the cohort at 4, 8, and 12 months after surgery (p<0.001 relative to baseline), respectively.

Low protein intake may lead to a loss of lean mass (instead of fat mass) and limited protein malnutrition,[20] among other consequences. For such reasons, these patients need to consume adequate amounts of protein.[3] These recommendations vary, in general, from between 60 and 120g/day,[1,3] with a consumption of more than 1g/kg of current body weight proving to be effective in promoting weight loss and preserving lean mass.[5] As the progression seen in TEI, protein also presents an evolution.[13] In the first six months postoperatively, bariatric patients can reach the average amount of 60g/day[4,14] and it is recommended that this value be increased to about 100g/day1 when the patient approaches one year postoperative.[3,5]

Carbohydrate recommendation. In determining the success of RYGB, %EWL should be larger than 50 percent, with long-term maintenance.[21] The quantity of carbohydrates consumed may influence such success. Despite the existence of several studies characterizing the food intake of the bariatric population it is known that the exact needs of macronutrients, especially of CHO,[22] for this population have not yet been defined.[7]

The current dietary reference intakes (DRIs) for macronutrients were based on short-term studies that reported biochemical markers and health and sickness parameters that presented satisfactory correlation to the proposed distribution of the macronutrients.[10] CHO recommendations are also based on the degree of the brain’s glucose usage. In order to maintain basic activities, the brain needs an average of 25g of glucose per day. However, the current DRIs (recommended dietary allowance [RDA]=130g/day) were made bearing in mind the ideal CHO minimum, which provides the brain with an adequate supply of glucose without the need of additional production through proteins and triglycerides, and without the need for an increase in the plasma concentration of ketone bodies above the concentration observed after a night of sleep (nocturnal fast).[10] The ADA proposes the same recommendation (130g/day).[11]

CHO acts to conserve protein.[10] When the consumption of CHO is too low, the amino acids are de-aminated and release carbon skeleton for energy supply. As a protein is going to be consumed as a source of energy, this may lead to a possible loss of muscle mass. In addition, the adherence to this kind of diet may be challenging for the patient. Considering that protein should be a top priority in the caloric ingestion for bariatric patients, CHO should be limited but not excluded. A minimal amount of CHO per day is needed for normal cell activity (namely red blood cells and neurons) given that this macronutrient is a basic source of energy. Accordingly, the Food and Agriculture Organization (FAO)/World Health Organization (WHO)[23] recommends a minimum consumption of 50g of CHO per day to maintain normal brain activity.

Clinically, it has been proven that a low intake of carbohydrates may cause some damage to the human body. A severe restriction of CHO (in diets of about 15g of CHO per day) may lead to an increase in low-density lipoprotein (LDL), following the increased consumption of foods rich in fat and low in nutritional value, thus raising the risk of cardiovascular diseases.[10] Furthermore, diets rich in fatty foods can induce a state of insulin resistance. Over time, these diets may cause acute ketonemia,[24] which can lead to metabolic acidity. Additionally, the specific recommendation of a high-protein intake and totally eliminating CHO from the diet has serious consequences to patients’ health, such as vitamin and mineral deficiencies and ketosis, which can lead to cognitive alteration and an increased glomerular filtration rate. Furthermore, long-term effects can include nephrolithiasis and osteoporosis.

On the other hand, a diet rich in CHO has its own consequences. It can favor an increase in triglycerides in the blood and LDL with atherogenic traits, a corresponding reduction in high-density lipoprotein HDL and an increase in the risk of cardiovascular diseases,[10] and may negatively influence the success of the surgery.[4] In recent study conducted by my colleagues and I,[4] we studied postoperative RYGB patients using data gathered through four 4-day food intake records (three of them collected on weekdays and one collected on the weekend). We applied a multivariate linear regression and found that excessive consumption of CHO was associated with less excess weight loss (EWL) and that CHO consumption can explain 63 percent of EWL.[4] In addition, patients have greater facility in consuming carbohydrates.[25] Actually, CHO rich food is more available and demands less effort to be swallowed. With this in mind, we should reinforce a high protein, low carbohydrate diet for the bariatric population.

Recently, Moize et al[22] proposed a food pyramid model for bariatric surgery, in which a CHO intake of between 40 and 45 percent of daily TEI was recommended. Considering the caloric intake for this patient population, such a recommendation represents an absolute CHO value of between 100 and 130g/day, adhering to the minimum amount recommended by the DRI[10] and ADA.[11] This quantity is very close to the recommended level for preventing ketosis (50 to 100 g/day)[10] and has been reported as having maximum protein-saving effect when taken daily.

In a randomized clinical trial studying individuals with obesity, Shai et al[26] found that after two years, those who consumed a diet with a maximum of 120g/day of CHO had a significantly higher weight loss, a greater drop in triglycerides, and a larger increase in HDL than individuals who followed a low-fat diet. These findings demonstrate that a diet with the indicated CHO quantities (a maximum of 120g/day) can be beneficial, favoring weight loss and maintenance, and improving comorbidities associated with obesity.

Another important factor related to CHO intake is the glycemic index (GI) of foods and glycemic load (GL) of meals.[27] High-GI foods (refined grains, potato and saccharides) raise blood glucose levels, which induces a greater increase in insulinemia.[4,11] Since insulin is an anabolic hormone, there is a higher risk for excess calories to be stored in the form of fat. Inversely, low-GI foods (e.g., whole foods, vegetables, whole grains. and some fruits) are those that cause lower peaks in the postprandial period. Studies have shown the efficiency of low-glycemic load diets on weight loss,[28] decreased body fat,[29] and improvement in comorbidities associated with obesity, such as an increase in HDL30 and a decrease in LDL, total cholesterol28 and triglycerides.[29]

In addition, low-GI diets have been investigated because of the associated increase in the induction of satiety30,31 and decrease in energy intake,[32] thus behaving as an important adjunct in a healthy process of loss and maintenance of weight. Within this context, our study4 found a negative correlation between the GL of meals and EWL among patients who had undergone RYGB at least six months previously. These findings highlight the importance not only of the quantity, but also the quality of CHO to be consumed by the bariatric population.

Considering that patients six months after surgery can ingest, on average, 850kcal/d, findings in the literature show that they usually consume about 30 percent of calories as lipids.[4,12,14] Following the recommendation of a minimum of 60g of protein per day,[1,3] they should consume about 40 to 45 percent of CHO, which represents an average consumption of 90g/day. This measure helps the patient to not exceed the 130g/day carbohydrate intake and to achieve the necessary quantities of protein for this stage.

After the first year, when TEI is about 1,300 kcal/d,[4,11,15] protein consumption levels should be increased.[13] We can, therefore, establish that 40 percent of a patient’s diet should be supplied by CHO, reflecting a diet of nearly 120g/day of CHO. Thus, based on food intake research and protein recommendations, and linking these data with our cross-sectional study and other studies carried out among the general population, we propose that a CHO consumption level of 90g/day be followed at six months after bariatric surgery, and less than 130g/day starting from the first year after surgery, corresponding to an average of 40 percent of daily TEI. In Table 6, our recommendations of macronutrient ingestion are given for patients who have undergone bariatric surgery.

As a result, considering anatomical restrictions from bariatric surgery and an adequate consumption of protein, a diet with moderate CHO restriction, rich in protein, and with low GL is recommended;26 however, it should be stressed that there are four important exceptions to this recommendation: 1) pregnancy after bariatric surgery, 2) postoperative plastic surgery, 3) patients who lost more than 100 percent EWL, and 4) patients who practice more than 90 minutes of physical exercise daily.

The limitations of our study include small sample size and a lack of data related to body composition.

Conclusions
The proposal of a specific CHO recommendation related to adequate intake of this macronutrient after bariatric surgery is important. Analyses of the habitual food intake of the bariatric population, evaluations of recommendations made regarding adequate protein intake, along with the findings of our cross-sectional study, as well as additional research in these areas carried out among the general population can serve as a guide for CHO recommendations for bariatric patients.

In this present review article, we have correlated the intake of up to 130g of CHO per day to a satisfactory weight loss in the postoperative stage. Allied with data from the literature reviewed, we recommend that patients who are six months postoperative should consume 90g of CHO daily and patients who are more than one year postoperative should reach a level of 130g of CHO daily. Thus, the need to maintain CHO consumption to moderately restricted quantities (based on low GL) and to stimulate a high and adequate protein intake among the bariatric population is fundamental to ensure full benefits from the surgery.

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