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Efficacy of High Carbohydrate versus High Protein Meal Replacements on Weight Reduction - A Randomized Controlled Trial | OMICS International
ISSN: 2165-7904
Journal of Obesity & Weight Loss Therapy
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Efficacy of High Carbohydrate versus High Protein Meal Replacements on Weight Reduction - A Randomized Controlled Trial

Katharina Möller*, Janina Willers and Andreas Hahn
Institute of Food Science and Human Nutrition, Leibniz University Hannover, Germany
Corresponding Author : Katharina Möller
Leibniz University of Hannover
Institute of Food Science and Human Nutrition
Am Kleinen Felde 30, 30167 Hannover
Germany
Tel: +49 (0)511-762 3317
Fax: +49 (0)511-762 5729
E-mail: [email protected]
Received May 06, 2015; Accepted June 8, 2015; Published June 30, 2015
Citation: Möller K, Willers J, Hahn A (2015) Efficacy of High Carbohydrate Versus High Protein Meal Replacements on Weight Reduction-A Randomized Controlled Trial. J Obes Weight Loss Ther 5:266. doi:10.4172/2165-7904.1000266
Copyright: ©2015 Möller K, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Abstract

Background: While formula diets as meal replacements are evident for weight loss, the macronutrient composition is still in the focus of interest. This study was designed to determine effects of a carbohydrate-riched meal replacement on weight loss and waist circumferences (WC) in comparison with a protein-riched meal replacement. Methods: Two groups (high carbohydrate formula diet (HC) and high protein formula diet (HP)) of 80 matched subjects each underwent a randomized parallel intervention trial for eight weeks followed by a 12-week follow-up. The intervention consisted of three phases: (1) week 1 and 2: total replacement of three meals, (2) week 3 and 4: replacement of two meals and (3) week 5 to 8: replacement of one meal. Measurements were taken at week 0, 2, 8, and 20. Results: After two weeks of total meal replacement, there was a significant (p<0.001) weight loss in both groups (HC: -4.0 ± 4.7 kg vs. HP: -4.3 ± 1.8 kg). After eight weeks, 66.2% of all subjects achieved a weight loss of 5% and more (HC: -8.5 ± 2.5%, p<0.001 vs. HP: -8.8 ± 2.8%, p<0.001), and 18.2% of the participants lost more than 10% of their initial body weight. Waist circumferences decreased from 105.9 ± 9.7 cm to 97.4 ± 8.4 cm (p<0.001) after eight weeks. During the follow up, further weight loss was observed in both groups. There were no significant differences between the HC and HP-group regarding changes in weight and WC. Conclusion: Both dietary intervention strategies had a similar effect on weight loss and WC reduction. In this short-term study macronutrient compositions of meal replacements are not crucial for the efficacy of formula diets. Trial registration: German Clinical Trials Register DRKS00005481.

Abstract

Background: While formula diets as meal replacements are evident for weight loss, the macronutrient composition is still in the focus of interest. This study was designed to determine effects of a carbohydrate-riched meal replacement on weight loss and waist circumferences (WC) in comparison with a protein-riched meal replacement.

Methods: Two groups (high carbohydrate formula diet (HC) and high protein formula diet (HP)) of 80 matched subjects each underwent a randomized parallel intervention trial for eight weeks followed by a 12-week follow-up. The intervention consisted of three phases: (1) week 1 and 2: total replacement of three meals, (2) week 3 and 4: replacement of two meals and (3) week 5 to 8: replacement of one meal. Measurements were taken at week 0, 2, 8, and 20.

Results: After two weeks of total meal replacement, there was a significant (p<0.001) weight loss in both groups (HC: -4.0 ± 4.7 kg vs. HP: -4.3 ± 1.8 kg). After eight weeks, 66.2% of all subjects achieved a weight loss of 5% and more (HC: -8.5 ± 2.5%, p<0.001 vs. HP: -8.8 ± 2.8%, p<0.001), and 18.2% of the participants lost more than 10% of their initial body weight. Waist circumferences decreased from 105.9 ± 9.7 cm to 97.4 ± 8.4 cm (p<0.001) after eight weeks. During the follow up, further weight loss was observed in both groups. There were no significant differences between the HC and HP-group regarding changes in weight and WC.

Conclusion: Both dietary intervention strategies had a similar effect on weight loss and WC reduction. In this short-term study macronutrient compositions of meal replacements are not crucial for the efficacy of formula diets.

Trial registration: German Clinical Trials Register DRKS00005481.
 
Keywords

Meal replacement; Formula diet; Weight loss; High carbohydrate; High protein
 
Introduction

Obesity and related diseases have become a worldwide problem of public health. Currently, an estimated 39% of the adult population is categorized as overweight and 13% as obese [1]. Given the prevalence of obesity, effective strategies are necessary for the prevention and treatment of obesity [2]. Energy reduction and low caloric diets have consistently been proven to encourage weight loss and to have beneficial health effects in obese subjects [3].

Therefore, formula diets as meal replacements have already been accepted as useful therapeutic strategies for weight loss in the evidence-based guidelines [4]. Meal replacement strategies cause weight reduction by creating greater energy deficit than is usual with a conventional diet [5] and are widely used to attain initial weight loss [4,6]. Due to the micronutrient composition laid down in European directives, formula diets ensure adequate intake of minerals, trace elements and vitamins [7]. Several studies have demonstrated that weight loss and weight maintenance was greater in the meal replacement groups compared to the conventional energy restricted diets while the calorie goal for the groups was equivalent [8-10]. Meal replacements coupled with low-calorie diet considerably increase the number of responders [11,12] and provide an effective option for weight reduction in overweight and obese subjects [13,14].

A further recommended strategy for achieving a reduction in energy balance is modifying macronutrient composition. There is still interest in whether the sources of energy in the diet might be the most beneficial for weight loss and weight maintenance [15]. Several randomized controlled trials observed favorable short-term effects of a high protein diet on body weight [16,17]. A high protein (HP) diet might increase the amount of weight loss by a reduction in appetite and increased thermogenesis [18]. On the other side, successful effects of high carbohydrate (HC) diets for weight loss have also been proven [19-22].

However, reduced energy intake for weight loss and maintenance by modification of macronutrient distribution is difficult to maintain by conventional dietary approaches, mostly due to the increase levels of hunger [23]. The individuals may have some difficulties in selecting or cooking the complicated low-calorie menus, in which various factors such as energy, carbohydrates, proteins or fat are involved. Hence, deficiency of macro- and micronutrients can occur [24,25].

Therefore, we aimed to determine the effect on weight loss using a HC meal replacement compared to a HP meal replacement. A novel aspect of this study was the use of two low-fat meal replacements either high in carbohydrates or high in proteins as a method for providing a diet with recommended daily intake that is feasible to sustain.
 
Materials and Methods

Study design and population

This trial was designed as an 8-week, single center, randomized, double-blind and parallel group intervention study, including a follow-up of twelve weeks. The study protocol was approved by the Ethical Committee of the Medical Chamber of Lower Saxony (Ärztekammer Niedersachsen) on 21th November 2013. Written informed consent was obtained from all subjects according to the guidelines for Good Clinical Practice. The clinical investigation was registered in the German Clinical Trials Register with the identification number DRKS00005481.

The study was carried out at the Institute of Food Science, Leibniz University Hannover, Germany. Subjects were recruited through advertisements in daily newspapers and pre-screened via structured telephone interviews. The criteria for participation were: (1) age 30-65 years, (2) body mass index (BMI between 27.9 and 35.1 kg/m2). Exclusion criteria were defined as major chronic diseases (e. g. cancer diseases, manifest cardiovascular disease (CVD), insulin-dependent type 1 or 2 diabetes, severe renal or liver diseases, endocrine and autoimmune diseases), gastrointestinal disorders (e. g. ulcers, chronic inflammatory bowel diseases, coeliac disease, pancreatitis), prior gastrointestinal surgical procedures (e.g. gastrectomy, short bowel syndrome, gastric bypass, gastric banding, stomach balloon), lactose intolerance, pregnancy, breastfeeding, and alcohol or drug addiction. Additionally, subjects were excluded if currently following a diet or taking any supplements that could interfere with the given preparations. The existence of inclusion and exclusion criteria was audited using a structured questionnaire sent by post. After returning the completed admission questionnaire, subjects meeting the inclusion criteria without the presence of any exclusion criteria were included and invited to the first examination (t0). Subjects (stratified according to their gender and BMI) were assigned to their respective intervention groups by means of block randomization appropriate to the sample size. The chief investigator, investigators, study staff, and participants were all blinded to the treatment allocation. One hundred and sixty overweight (12%) and obese (88%) subjects (n=94 females, n=66 males) were enrolled in the trial in February 2014.

The participants consumed either a HC formula diet or a HP formula diet. Study products were provided by Certmedica International GmbH (Aschaffenburg, Germany). They were administered daily as a drink meal replacement. Shakes were prepared by combining 30 g of powdered HC formula diet and 34 g of powdered HP formula diet with 300 ml milk (low fat) and 5 g vegetable oil. The macronutrient composition of the HC formula diet was approximately 24% protein, 49% carbohydrate, 25% fat, and 2% fiber relating to the recommended preparation. The macronutrient composition of the HP formula diet was approximately 38% protein, 34% carbohydrate and 28% fat. The nutritional composition of the two preparations is presented in Table 1.

Within the first two weeks of intervention, subjects were advised to replace three meals a day. The received low-calorie diet provided 800 kcal/3347 kJ per day. Subjects could add the daily intake with a hand-full of vegetables. Therefore, the low calorie diet provided a total of 800 to 1000 kcal (3347 to 4184 kJ) per day. In week 3 and 4, the subjects consumed two meal replacements for both, lunch and dinner. During the last intervention period (week 5 to 8), participants were encouraged to replace either lunch or dinner (depending on the daily routine). During the follow-up, the formula diets were taken ad libitum.

All participants received preparation instructions as well as recipe suggestions for the meal replacement drinks to avoid monotony and to offer variation in the preparation. Week 2 to 8, breakfast and either lunch or dinner were prepared according to the principles of a balanced whole food diet and based on national recommendations (German Nutrition Society). A recipe book was given to all participants to encourage healthy eating habits. The required amount of investigational products in neutral packaging was provided to the participants prior to the trial commencement and after two weeks. At the end of the study, the remaining formula powders were weighed to check compliance.

After 4, 7 and 19 weeks, all participants filled in a three daynutrition protocol which was typically kept for two weekdays and one weekend day, respectively. Thus, three nutrition protocols were available from each subject. Nutrition calculations were carried out using PRODI® (Nutri-Science GmbH, Freiburg, Germany).
 
Questionnaires, anthropometric measurements

Anthropometric measurements were taken at baseline, after 2, 8, and 20 weeks (t0, t2, t8, t20). The height was measured once at the beginning of the study in an upright position without shoes with a stadia rod (SECA, Model 217, seca gmbh & co kg, Germany). Body weight was recorded dressed in light clothes and without shoes. Waist circumference (WC) was measured at the midpoint between the lower border of the rib cage and the top of the iliac crest. Hip circumference (HipC) was defined as being the widest circumference over the buttocks. The measurements of the WC and HipC were taken with the subjects standing relaxed, breathing normally, with the measuring tape placed horizontally. The waist-to-hip ratio (WHR) was calculated. Blood pressure was measured under standardized conditions after 10 min. resting period. The examinations were performed in the morning after an overnight fasting period of at least 12 h.
 
Statistical analysis

Statistical comparison between the HC and HP group were performed using the nonparametric Mann-Whitney U test for unpaired data. The changes in the parameters in comparison with baseline were analyzed using the Wilcoxon test. The chi-square test was used to compare the difference between the frequencies of the two groups. Differences were considered significant at p<0.05. The results were shown as the mean value ± standard deviation (s.d.).

A modified intention-to-treat (mITT) population was evaluated comprising subjects with a baseline value (t0) and at least one further measurement value. For all subjects the missing values were constantly updated with the last observation carried forward after the prior measurements. The statistical data analysis was carried out by using the Statistical Package for Social Sciences SPSS 21.0 (SPSS Inc., Chicago, Illinois, USA).
 
Results

Baseline characteristics

A total of 280 individuals were pre-screened for this study. 85 subjects did not fulfill the inclusion criteria and were excluded during screening. Subjects from the waiting list moved up if others did not fulfill the BMI criteria at the baseline visit. 80 participants were randomized either to the HC or to the HP group. Six participants (3.9%) dropped out before week 2 (t2) because of intolerance to the study formula diet, acute illness or other reasons. Consequently, 154 participants were included in the mITT analysis: 78 of them received HC formula diet (n=45 female, n=33 male) and 76 the HP formula diet (n=45 female, n=31 male). After completion of the follow-up in week 20, 103 participants remained in the study (60 in the HC group and 43 in the HP group). A flowchart is illustrated in Figure 1. At baseline, no differences were observed between both groups regarding to the parameters listed in Table 2. Preobestiy (27.0-29.9 kg/m2) applied to 14 subjects (9%), 131 subjects (85%) had obesity stage I (30.0-34.9 kg/m2) and 9 subjects (6%) could be allocated to obesity stage II (35.0-39.9 kg/m2).
 
Energy intake and macronutrient intake

At baseline, the dietary intakes of energy (kJ/day), carbohydrates, protein and fat were similar in both groups (Table 3). During the two weeks of total meal replacement, energy intake was reduced by 65.2% from baseline in the HC group (p<0.001) and by 60.1% in the HP group (p<0.001). At week 4 and 7, energy intake continual increased, but reduced energy intake was still maintained throughout the study in both groups. At week 2 and 4, absolute carbohydrate intakes and percent of energy from carbohydrates in the HC group increased compared to baseline (p<0.001 each). Percent energy intake from carbohydrates in the HC group were greater than in the HP group at week 2, 4 (p<0.001 each) and 7 (p<0.05). Percent energy derived from protein increased in both groups at week 2, 4 and 7 compared to baseline (p<0.001 each). However, the increase was significantly lower in the HC group. Absolute intake of fat decreased in the HC group (p<0.001) and in the HP group (p<0.001), as well as percentage from fat in both groups (p<0.001 each). There was no significant difference in fat intake between the groups. Nevertheless, at week 2 absolute intake of fat and percentage intake from fat was modestly higher in the HP group than in the HC group (p<0.05). Comparison of the groups showed a slightly higher fiber intake for the HC group (p<0.05). In both groups, fiber intake compared to baseline decreased at 2, 4 and 7 weeks (p<0.001 each) and was greater in the HC group than in the HP group (p<0.001 each).
 
Changes in anthropometric data

A significant weight loss of 4.0 ± 1.7 kg (4.1%) in the HC group and 4.3 ± 1.8 kg (4.5%) in the HP group after two weeks and of 6.5 ± 3.5 kg (6.6%) in the HC group and 6.8 ± 3.6 (7.0%) in the HP group after 8 weeks was observed. In the HP group, weight loss was 0.27 kg higher than in the HC group. Although difference between the two groups was statistically not significant (Table 4). Furthermore, the number of subjects who lost 0 - ≤ 5%, >5 - ≤ 10% and >10% of initial body weight after eight weeks of intervention was analyzed. A total of 29.6% individuals in the HC group (n=38) lost between 5 and 10% of initial body weight. Whereas 27.4% (n=36) in the HP group lost >5-10% of their initial body weight (Figure 2). In Detail, 46 subjects (n=19 HC group, n=27 HP group) lost >5% of their initial body weight in the first two weeks.

Figure 3 shows weight loss as percentage of initial body weight in subjects who lost ≤5% or >5% of initial body weight in the first two weeks, with regard to the diet intervention groups. Subjects who lost >5% of initial body weight in the first two weeks had a higher weight loss after eight weeks than participants who lost ≤5% of initial body weight (p<0.001). Both groups maintained significant weight loss (from baseline to week 20) with a mean net loss of 7.1 ± 5.1% (p<0.001) in the weight loss group ≤5% of initial body weight and 9.2 ± 5.6% (p<0.001) in the weight loss group >5% of initial body weight. There was a significantly difference between groups (p<0.05). During the follow up, HC group gained weight compared to week 8 of intervention, however this weight gain was not significant different to the HP group. After the 8-week intervention, there was also a significant reduction in the mean BMI from obesity stage I to preobesity in both groups (Table 4). At week 8, WC decreased by a mean of 8.6 cm (8.0%) in the HC group and 8.3 cm (7.8%) in the HP group (p<0.001). Correspondingly, waist-to-hip ratio (WHR) significantly decreased to a similar extent.
 
Adverse events and side effects

Incidences of all kind of adverse events (e.g. common cold) were comparatively similar in both treatment groups. At visit t2, there were statistically significant differences between the HC and the HP group in the proportion of subjects with flatulence and diarrhea. While flatulence occurred significantly more frequent in the HC group (n=13 vs. n=4; p<0.05, chi-square test), complaints of diarrhea (n=8) only occurred in the HC group (p<0.005), (multiple answers were possible). Also at week 8, diarrhea (n=8) only occurred in the HC group (p<0.05; chi-square test). Effects such as nausea, eructation or bloating were rarely mentioned.
 
Discussion

Our results indicate that both weight loss strategies are effective treatment options for overweight and obese women and men. In the first two weeks, we chose three formula diets per day to take account of a total meal replacement diet plan on weight loss. In accordance to studies which used low calorie diets (800-1000 kcal/day) for weight loss [26,27], the results of this intervention can deliver weight loss rates of 2 kg per week. We further chose formula diets with partial meal replacement for week 5 to week 8 of intervention, because of being more flexible than total meal replacement plans [8]. In both groups, the average weight loss was maintained with additional losses within the last six weeks. Weight loss effects were more pronounced in total meal replacement plan than in partial meal replacement plan. This was expected. The difference is most likely due to the fact that restricted energy intake in the first two weeks. Our results are consistent with those reported by Hemmingsson et al. Overweight and obese subjects achieved significant more weight loss after being prescribed with a liquid-based formula diet (providing approximately 500 kcal/day) compared to a 1200-1500 kcal diet, consisting of two meal replacements and a reduced-calorie dinner meal [28].

After eight weeks of intervention, mean weight loss in both groups (6.5 ± 3.5 kg in HC group and 6.8 ± 3.6 kg in HP group) were similar to other studies done previously (5.9-7.4 kg) which lasted twelve weeks [10,12,29]. A modest weight loss up to 5% has been shown to reduce the risk of developing obesity associated diseases [30]. Weight loss of 5% and more (equivalent to 4.9 kg of mean initial body weight of the total study group) was exceeded by at least 1.6 kg in the HC group and by 1.9 kg in the HP group, reflecting a decreasing risk in both groups. Moreover, it has been shown that weight loss of around 5 kg, as achieved by 66.2% of subjects, is associated with a reduction in all-cause mortality [31].

In order to determine the energy and macronutrient intake, all participants were instructed to keep 3-day food records at baseline, week 4 and 7 during the trial, as well as week 19 of the follow-up. It is useful to consider that self-reported food diaries may not provide highly accurate information. But well-kept food records delivered data were used to assess macronutrient intake and also to compare the results with those from other dietary trials. In the present study, weight reduction was not significantly different in the HP group compared to the HC group. These results disagree with trials which had shown that increased protein as a percentage of total calories can enhance weight loss [16,32] and that HP diets lead to more weight loss than HC diets [33]. At week 2, the protein intake was about 0.5 g/kg body weight in the HC group and 1.1 g/kg body weight in the HP group. Protein intake increased to 0.7 g/kg body weight in the HC group and declined to 0.9 g/kg body weight in the HP group during the partial meal replacement plan. In two studies lasted three months, protein intake of 1.2 or 0.9 g protein/kg body weight was more effective on weight loss than 0.8 or 0.6 g protein/kg body weight [34,35]. Analysis of food records also showed significant reduction in percentage of fat intake in both groups from baseline. Recent research indicates that substitution of carbohydrates or proteins for fat is associated with weight loss [21]. Furthermore, diets high in protein with low glycemic index are associated with an increase satiating and decreased energy intake, which achieved weight loss [18,33,36]. However, in both groups, food records showed that the energy intake was decreased to the same extent throughout the intervention. Sacks et al. (2009) have demonstrated that the most important factor influencing weight loss over term is creating a state of negative energy balance [37]. Therefore, the mechanism responsible for the weight loss caused by HC formula diet and HP formula diet can be attributed to a reduced energy intake. Overall weight reduction was probably not caused by an increase in physical activity determined in the questionnaires. The levels of physical activity reported were similar in both groups.

In addition, this randomized trial in overweight and obese people had useful effects on abdominal fat reduction. The role of body fat distribution phenotype has been shown to be even more essential than body weight [38]. Visceral fat is attended by a higher cardio metabolic risk compared to high proportions of subcutaneous risk. Therefore, reduction in WC is regarded to be more important than weight loss exclusively [39]. At week 8, the significant decrease in WC by 9.3 ± 5.4 cm in males and 7.9 ± 7.0 cm in females indicates that the body fat distribution phenotype has changed. This could be of major clinical interest, because even a 3 cm reduction of WC results in a significant improvement of cardio metabolic risk factors [40]. A general cutoff of 102 cm in men and 88 cm in women has been shown for WC [41]. However, these values were not achieved in women at any time of the study. On the contrary, after the follow up men with higher protein intake obtained values below the general cutoff. There are two possible reasons for the observed gender differences. Firstly, males entered the study with higher body mass index and lost essentially more weight. Secondly, low calorie diets mean more restriction in energy intake for males than for females [42].

One argument against the use of formula diets is the rapid weight gain afterwards [43]. In the present study, subjects who lost more than 5% of body weight in the first two weeks, maintained greater weight reduction during the intervention and follow-up. This result is in accordance with Purcell and colleagues who reported that initial rate of weight loss did not affect the amount of weight regain [44]. Furthermore, Christensen et al. (2013) demonstrated that partial use of formula diets showed statistically significant better weight maintenance than the control group [45]. Studies looking at weight maintenance over 24 to 26 weeks after weight loss reported that a diet with high protein intake [46] and reduction in glycemic index [27] led to an improvement in maintenance of weight loss. In the present study, subjects with higher protein intake during the follow-up demonstrate no differences in weight maintenance compared to HC group.
 
Limitations

First, the remaining powder of the formula diets was weighted to control compliance. It had been shown that the measuring spoon supplied in both groups did not enter the predefined quantity of formula diet. Therefore, there was great variability. Second, although physical activity has been monitored during the study, the actual influence cannot be quantified. Third, this study may represent only a short-term effect over eight weeks. The short duration of intervention could have led to an underestimation of the full potential of HC and HP diet plan. With a view to lasting weight maintenance, long-term effects are required.
 
Conclusion

In conclusion, both formula diets were safe and had similar effects in weight and abdominal fat reduction. Based on these findings, individuals who have preferences to consume favorable proteins for weight reduction, a HC meal replacement diet offers an alternative for those, who choose not to increase protein intake.
 
Acknowledgement

The provision of test products by Certmedica International GmbH (Aschaffenburg, Germany) is kindly acknowledged. The authors are solely responsible for the design and conduct of the study, collection, management, analysis, and interpretation of the data, as well as preparation of the manuscript. All authors had full access to the data and take responsibility for its integrity. All authors have read and agree with the manuscript as written. We would like to thank the participants who contributed their time to this project.
 
References


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