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Author Manuscript
N Engl J Med. Author manuscript; available in PMC 2012 May 24.
Published in final edited form as:
N Engl J Med. 2010 November 25; 363(22): 2102–2113. doi:10.1056/NEJMoa1007137.

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Diets with High or Low Protein Content and Glycemic Index for
Weight-Loss MaintenanceEurope PMC Funders Author Manuscripts

Thomas Meinert Larsen, Ph.D., Stine-Mathilde Dalskov, M.Sc., Marleen van Baak, Ph.D.,
Susan A. Jebb, Ph.D., Angeliki Papadaki, Ph.D., Andreas F.H. Pfeiffer, M.D., J. Alfredo
Martinez, Ph.D., Teodora Handjieva-Darlenska, M.D., Ph.D., Marie Kunešová, M.D., Ph.D.,
Mats Pihlsgård, Ph.D., Steen Stender, M.D., Ph.D., Claus Holst, Ph.D., Wim H.M. Saris, M.D.,
Ph.D., and Arne Astrup, M.D., Dr.Med.Sc. for the Diet, Obesity, and Genes (Diogenes)
Project
Department of Human Nutrition, Faculty of Life Sciences (T.M.L., S.-M.D., A.A.), and theDepartment of Clinical Biochemistry, Gentofte Hospital (S.S.), University of Copenhagen; and theInstitute of Preventive Medicine, Copenhagen University Hospital (M.P., C.H.) — all in
Copenhagen; the NUTRIM (Nutrition and Toxicology Research Institute Maastricht) School for
Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University
Medical Centre, Maastricht, the Netherlands (M.B., W.H.M.S.); the Medical Research Council
Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, United Kingdom (S.A.J.);
the Department of Social Medicine, Preventive Medicine, and Nutrition Clinic, University of Crete,
Heraklion, Crete, Greece (A.P.); the Department of Clinical Nutrition, German Institute of Human
Nutrition Potsdam-Rehbrücke, Nuthetal, Germany (A.F.H.P.); the Department of Endocrinology,
Diabetes, and Nutrition, Charité Universitätsmedizin Berlin, Berlin (A.F.H.P.); the Department of
Physiology and Nutrition, University of Navarra, Pamplona, Spain (J.A.M.); the Department ofPharmacology and Toxicology, Medical Faculty, National Transport Hospital, Sofia, Bulgaria(T.H.-D.); and the Obesity Management Center, Institute of Endocrinology, Prague, Czech
Republic (M.K.).

Abstract
Background—Studies of weight-control diets that are high in protein or low in glycemic index
have reached varied conclusions, probably owing to the fact that the studies had insufficient
power.
Methods—We enrolled overweight adults from eight European countries who had lost at least
8% of their initial body weight with a 3.3-MJ (800-kcal) low-calorie diet. Participants wererandomly assigned, in a two-by-two factorial design, to one of five ad libitum diets to prevent
weight regain over a 26-week period: a low-protein and low-glycemic-index diet, a low-protein
and high-glycemic-index diet, a high-protein and low-glycemic-index diet, a high-protein andhigh-glycemic-index diet, or a control diet.
Results—A total of 1209 adults were screened (mean age, 41 years; body-mass index [theweight in kilograms divided by the square of the height in meters], 34), of whom 938 entered the
low-calorie-diet phase of the study. A total of 773 participants who completed that phase wererandomly assigned to one of the five maintenance diets; 548 completed the intervention (71%).
Fewer participants in the high-protein and the low-glycemic-index groups than in the low-protein–

Copyright © 2010 Massachusetts Medical Society. All rights reserved.
Address reprint requests to Dr. Larsen at the Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen,Rolighedsvej 30, 1958 Frederiksberg, Copenhagen, Denmark, or at tml@life.ku.dk..
No other potential conflict of interest relevant to this article was reported.
Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.

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high-glycemic-index group dropped out of the study (26.4% and 25.6%, respectively, vs. 37.4%; P= 0.02 and P = 0.01 for the respective comparisons). The mean initial weight loss with the lowcalorie diet was 11.0 kg. In the analysis of participants who completed the study, only the lowprotein–high-glycemic-index diet was associated with subsequent significant weight regain (1.67kg; 95% confidence interval [CI], 0.48 to 2.87). In an intention-to-treat analysis, the weight regain
was 0.93 kg less (95% CI, 0.31 to 1.55) in the groups assigned to a high-protein diet than in those
assigned to a low-protein diet (P = 0.003) and 0.95 kg less (95% CI, 0.33 to 1.57) in the groups
assigned to a low-glycemic-index diet than in those assigned to a high-glycemic-index diet (P =0.003). The analysis involving participants who completed the intervention produced similar
results. The groups did not differ significantly with respect to diet-related adverse events.
Conclusions—In this large European study, a modest increase in protein content and a modest
reduction in the glycemic index led to an improvement in study completion and maintenance of
weight loss. (Funded by the European Commission; ClinicalTrials.gov number, NCT00390637.)
The importance of the composition of a diet for the prevention and management of obesity is
debated. Ad libitum consumption of low-fat diets results in short-term weight loss,1 andlow-carbohydrate, high-protein, and high-fat diets (e.g., the Atkins diet) may result in
substantial weight loss as compared with that achieved with other types of diets.2 However,
the weight loss is generally not sustained beyond 1 year.3 Greater weight loss with lowcarbohydrate diets may be ascribed to the satiating effects of high protein content,4 and there
is increasing interest in the efficacy of diets that have a high protein content with a moderate
carbohydrate and fat content.5-7

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A diet with a low glycemic index may have beneficial effects on body weight and bodycomposition8,9 and on certain risk factors in overweight persons,9,10 but the effectiveness ofad libitum consumption of low-glycemic-index diets for weight control is controversial.9
The Diet, Obesity, and Genes (Diogenes) study is a pan-European, multicenter, randomized,
dietary-intervention study designed to assess the efficacy of moderate-fat diets that vary inprotein content and glycemic index for preventing weight regain and obesity-related risk
factors after weight loss. We report here the results of the 26-week weight-maintenanceintervention phase of the study.

Methods
Study Protocol
The study design, methods, and procedures have been described in detail previously.11 The
study was conducted in eight European countries: Denmark, the Netherlands, the United
Kingdom, Greece (Crete), Germany, Spain, Bulgaria, and the Czech Republic. The overall
study leaders, together with the principal investigator at each study center, designed thestudy. The principal investigator at each study center collected the local data, which wereentered into a data-registration system (EpiData)12 and transferred to a central data hub. The
European Commission Food Quality and Safety Priority of the Sixth Framework Programme(the main sponsor of the study) had no role in the design of the study or in the analysis orinterpretation of the data. The protocol, including the statistical analysis plan, is available
with the full text of this article at NEJM.org. The authors attest that the study was performedin accordance with the protocol and the statistical analysis plan.
Study Participants
Families that included at least one healthy child between 5 and 17 years of age and at least
one parent between 18 and 65 years of age who was overweight or obese (body-mass index[the weight in kilograms divided by the square of the height in meters] of at least 27 and lessthan 45) were recruited for the study. Overweight or obese parents who had achieved the

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targeted weight loss (≥8% of their baseline weight) during the 8-week low-calorie-dietperiod were randomly assigned with their families to one of five maintenance diets for 26
weeks; randomization was performed with the use of a simple block randomization
procedure with stratification.11 Of 1209 adults screened, 938 started the low-calorie-dietperiod. After completion of this phase of the study, 773 participants entered the weightmaintenance phase (Fig. 1). Results for nonobese adults and children in the study families
are not reported here.
Weight-Loss Phase
During the 8-week weight-loss phase, participants received a low-calorie diet that provided
3.3 MJ (800 kcal) per day with the use of Modifast products (Nutrition et Santé).
Participants could also eat up to 400 g of vegetables, providing a total, including the lowcalorie diet, of 3.3 to 4.2 MJ (800 to 1000 kcal) per day.
Weight-Maintenance Phase
In the randomized maintenance phase, which was initiated immediately after participants
completed the weight-loss phase, participants were assigned to one of five diets, in a twoby-two factorial design: a diet that was low in protein (13% of total energy consumed) witha low glycemic index, a diet that was low in protein with a high glycemic index, a diet thatwas high in protein (25% of total energy consumed) with a low glycemic index, a highprotein and high-glycemic-index diet, or a control diet. The control diet, which followed
dietary guidelines in each participating country, had a moderate protein content and did notinclude instructions to participants with respect to the glycemic index.

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Study participants were instructed to maintain their weight loss during this phase, althoughfurther weight reduction was allowed. All five diets were designed to have a moderate fat
content (25 to 30% of total energy consumed) with no restrictions on energy intake (i.e., adlibitum diets), in order to test the ability of the diets to regulate appetite and body weight.
We targeted a difference of 15 glycemic-index units between the high-glycemic-index dietsand the low-glycemic-index diets and a difference of 12% of total energy consumed fromprotein between the high-protein diets and the low-protein diets. Visits for dietary
counseling took place every other week during the first 6 weeks and monthly thereafter. The
families were provided with recipes, cooking and behavioral advice, and a point-basedteaching system to achieve the targeted macronutrient compositions.13
In Maastricht and Copenhagen (“shop centers”), the families received dietary instruction
plus free foods from the laboratory shop for 26 weeks so that we could assess the effect thatthe provision of food would have on adherence. In the other six centers (“instruction
centers”), the families were provided with dietary instruction only.14,15 Local sponsors madefinancial contributions to the shop centers, and food manufacturers provided a number offoods free of charge. The local sponsors and food manufacturers had no influence on theselection of foods found in the two shops, nor were they involved in designing the study orin analyzing and interpreting data.
Monitoring Food Intake
The study participants weighed their food and completed food diaries for 3 consecutive daysat the time of screening (9 to 11 weeks before randomized assignment to the maintenanceintervention), 4 weeks after randomization, and at the end of the 26-week intervention. The
calculation of nutrient intake was performed with the use of local food databases, as
described previously.11 Coding of food according to the glycemic index was performed
separately from coding according to nutrient intake. Values for the glycemic index werebased on glucose as a reference, as described previously.16 Blood samples were obtained
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before the intervention and at the end of the intervention, and urine samples before theintervention, at weeks 4 and 14, and at the end of the intervention, to assess adherence to thediet.11 A description of the method used for performing urinary analyses is provided in the
Supplementary Appendix, available at NEJM.org.
Statistical Analysis

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Estimates of the sample size were calculated with the assumption that after the 26-weekintervention, the smallest difference in weight change (estimated to be 1.0 kg) that would be
detected among the diet groups would be found between the groups assigned to lowglycemic-index diets and the groups assigned to high-glycemic-index diets. We estimatedthat a sample of 918 adults would be needed to detect a significant difference between thehigh-glycemic-index and low-glycemic-index groups, assuming a dropout rate of 20%.11
Dietary intakes were calculated for participants who completed food diaries, and changes
from screening to the end of the intervention phase were calculated only for study
participants who completed food diaries at both those times (393 participants). Mean intakesof energy and macronutrients, the glycemic index, and the glycemic load were comparedwith the use of one-way analysis of variance. When an overall significant difference in theeffect of dietary group was found, pairwise comparisons of the groups were performed with
Sidak’s adjustment for multiple comparisons.

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The intention-to-treat analysis included data from all participants who underwent
randomization. To account for bias resulting from different rates of dropout among thegroups, we used a mixed model to evaluate the weight changes (assessed at eight time points
during the 26-week intervention). This intention-to-treat model provides unbiased results
under the assumption that missing data were missing at random.17 The model considered allavailable weight recordings during the intervention for all participants who underwent
randomization and assumed that the weight changes in participants who dropped out of thestudy followed the same course. The analyses were adjusted for the body-mass index at thetime of randomization and the change in body weight from the beginning of the low-caloriediet phase to the time of randomization as covariates and diet group, sex, and type of center(shop or instruction) as factors. The interactions between diet and sex and between diet andtype of center were included in the model. It was assumed that the correlation between
weight regain at two visits decreased with the number of weeks between the visits and thatthe decrease per week was constant.
The completion analysis, which included all participants for whom data were available fromboth the time of randomization and the end of the trial intervention, was performed with theuse of analysis of covariance. In addition, a linear regression analysis was performed to test
the main effects of protein and glycemic index separately. In both analyses, we adjusted forthe same covariates as in the intention-to-treat analysis described above, as well as for thelength of time between randomization and the end of the intervention.
The influence of center, type of center (shop or intervention), sex, age at screening, bodymass index at the time of randomization, body weight lost during the low-calorie-diet phase,family type (single-parent family, two-parent family with one parent as participant, or twoparent family with both parents as participants), and diet on the dropout rate during themaintenance phase was analyzed with the use of a logistic model.
Results are presented as means ±SD, and estimates of effects as means and 95% confidence
intervals. Two-tailed P values of less than 0.05 were considered to indicate statisticalsignificance. The analyses were performed with the use of SAS software, version 9.1.

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Study Participants

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The participants in the five diet groups were well matched with respect to characteristics atbaseline (i.e., at the beginning of the low-calorie-diet phase) and at the time ofrandomization, with no significant between-group differences in changes during the lowcalorie-diet phase (Table 1). During the dietary-intervention period, 225 of the 773
participants who had undergone randomization (29%) dropped out of the study (Fig. 1). The
dropout rate was lower in the groups that were assigned to high-protein diets and the groups
that were assigned to low-glycemic-index diets than in the group that was assigned to thediet that was low in protein and had a high glycemic index (26.4% and 25.6%, respectively,
vs. 37.4%; P = 0.02 and P = 0.01 for the two comparisons, respectively). The low-glycemicindex diets were associated with a lower risk of dropout than were the high-glycemic-index
diets (odds ratio, 0.64; 95% confidence interval [CI], 0.44 to 0.92; P = 0.02), and there was atrend toward a lower risk of drop-out with the high-protein diets than with the low-protein
diets (odds ratio, 0.69; 95% CI, 0.48 to 1.00; P = 0.05).
Dietary Intake
Dietary intakes for all groups are shown in Table 2. The proportion of total energy
consumed from protein was 5.4 percentage points higher, and the proportion of total energy
consumed from carbohydrates was 7.1 percentage points lower, in the high-protein groups
than in the low-protein groups (P<0.001 for both comparisons). The mean glycemic index in
the low-glycemic-index groups was only 5 units lower than that in the high-glycemic-index
groups (P<0.001). There was a 71% (20.6-g-per-day) greater reduction in the glycemic loadin the high-protein groups than in the low-protein groups (P = 0.002). There were no
significant differences among the groups in the recordings of subjective appetite sensations(data not shown).
Markers of Adherence to Diet

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The urinary excretion of nitrogen during the maintenance period was greater by 2.09 g per
24 hours in the high-protein groups than in the low-protein groups (P<0.001) (Fig. 2A), andthe difference remained significant when the analysis included only participants from whom
more than 500 ml of urine had been collected and more than 80% but less than 120% paminobenzoic acid had been recovered. In addition, the plasma urea concentration was
higher in the high-protein groups than in the low-protein groups (between-group difference,
0.27 mmol per liter; P = 0.01).
Body Weight
Intention-to-Treat Analysis—The intention-to-treat analysis, performed with the use ofa mixed linear model, included all 773 participants who underwent randomization, of whom
705 attended at least one visit after randomization. The weight increase during themaintenance period was 0.93 kg (95% CI, 0.31 to 1.55) higher in the low-protein groups
than in the high-protein groups (P = 0.003) and 0.95 kg (95% CI, 0.33 to 1.57) higher in thehigh-glycemic-index groups than in the low-glycemic-index groups (P = 0.003) (Fig. 2B).
There was no significant interaction between the high-protein diets and the low-glycemicindex diets. We performed a sensitivity analysis, assuming a 1-kg weight gain per month inparticipants who had dropped out of the study. This analysis produced similar results — aweight increase that was 1.01 kg (95% CI, 0.24 to 1.78) higher in the low-protein groups
than in the high-protein groups (P = 0.01) and 0.99 kg (95% CI, 0.22 to 1.76) higher in thehigh-glycemic-index groups than in the low-glycemic-index groups (P = 0.01). The highprotein groups were more likely to achieve an additional weight loss of more than 5% of

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their body weight at randomization than were the low-protein groups (odds ratio, 1.92; 95%
CI, 1.06 to 3.45; P = 0.03), and the low-glycemic-index groups were more likely to achieve
an additional weight loss of more than 5% than were the high-glycemic-index groups (oddsratio, 2.54; 95% CI, 1.38 to 4.66; P = 0.003) (Table 3).

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Completion Analysis—In the analysis of 548 participants who completed theintervention, the mean (±SD) weight regain was 0.56±5.44 kg. Only the participants
assigned to the diet that was low in protein with a high glycemic index had significant
weight regain (1.67 kg; 95% CI, 0.48 to 2.87) (Table 2). The changes in body weight
differed among the diet groups (P = 0.01 by analysis of covariance). The isolated effect sizeof the high-protein diets as compared with the low-protein diets was 1.44 kg (95% CI, 0.50
to 2.33; P=0.02). The effect size of the low-glycemic-index diets as compared with the highglycemic-index diets was 1.09 kg (95% CI, 0.18 to 2.00; P = 0.02). The effects of protein
and glycemic index on body-weight changes in the shop centers were consistent with theresults in the instruction centers, but analyzing the centers separately reduced the statisticalpower. In the shop centers, the high-protein groups gained 2.7 kg less body weight than did
the low-protein groups (P<0.001), whereas the difference was 0.54 kg in the instruction
centers (P = 0.13). In the shop centers, the low-glycemic-index groups gained 0.48 kg lessthan did the high-glycemic-index groups (P = 0.48), whereas the difference was 1.03 kg in
the instruction centers (P = 0.004).
Adverse Events

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Four serious adverse events were reported during the weight-maintenance period. One
person assigned to the low-protein–low-glycemic-index diet presented with lower abdominal
pain but recovered without the need for hospitalization. Another person assigned to the lowprotein–low-glycemic-index diet who presented with abdominal pain and two persons
assigned to the low-protein–high-glycemic-index diet who presented with upper abdominal
pain were hospitalized; each had his or her gall bladder removed and recovered without
further consequences. The number of adverse events was lower in the group assigned to thediet that was low in protein with a high glycemic index than in any of the other groups, but
the pattern of adverse events does not suggest any causal relation to the diet (for further
details on adverse events, see the Supplementary Appendix).

Discussion
In this study, the rate of completion of the intervention and the rate of maintenance of
weight loss were higher among participants who were assigned to the high-protein diets andto the low-glycemic-index diets than among those who were assigned to the low-protein
diets and to the high-glycemic-index diets (with no restrictions on energy intake in any ofthe diets). In addition, the participants assigned to the diet that was high in protein with alow glycemic index continued to lose weight after the initial weight loss. The higher protein
content was achieved by reducing the carbohydrate content, which adds further support tothe concept that reducing the glycemic load (defined as carbohydrate content times glycemic
index) is important for controlling body weight in obese patients.8,18,19 No differences weredetected in self-perceived satiety, though we suspect that the effects were too subtle to be
subjectively perceived or measured with the use of visual-analogue scales.
The dietary intervention was carefully controlled to avoid differences in total fat, alcohol,
and fiber among the groups but did not fully achieve the targeted difference ofapproximately 12% of total energy consumed in protein between the high-protein and the
low-protein groups or the targeted difference of approximately 15 glycemic-index units
between the low-glycemic-index and the high-glycemic-index groups. The differences that

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were achieved in the study were 5.4 percentage points of total energy in protein content
between the high-protein and the low-protein groups and 4.7 glycemic-index units between
the low-glycemic-index and the high-glycemic-index groups.

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Measurement of urinary nitrogen excretion confirmed adherence to the diets (high-protein
vs. low-protein), but adherence decreased toward the end of the study. Suboptimal
adherence, perhaps owing to insufficient knowledge of the content of local foods, may haveaccounted for the failure to reach the targeted differences in protein and glycemic index.
However, the results indicate that even a modest increase in dietary protein or a modest
reduction in glycemic-index values was sufficient to minimize weight regain and promotefurther weight loss in obese patients after a successful weight-loss diet. Higher dietaryadherence might have resulted in even greater weight loss.
We used families as the unit of randomization, since we thought that adult participants
would be more likely to adhere to the diet if the entire family had the same diet. The
participants who underwent randomization in our study were probably a more adherent
group than participants in other studies, since they had adhered sufficiently to the lowcalorie diet (3.3 MJ [800 kcal] per day) for 8 weeks to lose at least 8% of their body weight.
Despite issues of adherence, we believe that our results are generalizable to obese people,
particularly if diets are facilitated by easy access to low-glycemic-index foods and a culturethat supports these dietary changes.
The dropout rate (29%) was higher than the expected rate of 20%,11 possibly owing todifficulty in maintaining motivation in whole families over the course of the 26 weeks of thestudy. Other dietary studies have reported similar dropout rates.3,18

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We conducted a smaller study with the shop model and ad libitum food, and we found thatafter a 6-month intervention, a high-protein diet resulted in weight loss that was 3.7 kg
greater than that achieved with a low-protein diet.19 The current study aimed to investigate
whether participants who have had a major weight loss could maintain the lower weight; theresults of the study are similar to those of McMillan-Price et al., who found that participants
following high-protein diets lost about 0.6 kg more than did participants following lowprotein diets over the course of 3 months.20
A reduction in the glycemic index of 4.7 units resulted in a 0.95-kg difference in bodyweight between the high-glycemic-index groups and the low-glycemic-index groups. Since
there were no differences in fiber intake, the difference in body weight, though small, can be
ascribed to a true effect of the glycemic index. This difference is consistent with results froma previous study.21 Furthermore, a Cochrane meta-analysis of intervention studies showedthat there was a 1.1-kg greater weight loss with low-glycemic-index diets than with highglycemic-index diets.9 However, previous studies were designed to investigate weight loss,
not weight maintenance, rendering direct comparisons difficult. McMillan-Price et al. did
not observe a significant difference in weight loss between diets that differed by 20
glycemic-index units.20 Sloth et al. found a 0.6-kg (nonsignificant) difference between dietsthat differed by 24 glycemic-index units.22 Philippou et al. found no significant differencesin weight change between maintenance diets that differed by 14 glycemic-index units(approximately 1.0 kg).23
The effects of protein and the glycemic index on changes in body weight that we found in
the shop centers were consistent with those at the instruction centers. However, subgroup
analyses suggested that the high-protein diets were more effective at the shop centers,
whereas the low-glycemic-index effect was greater at the instruction centers. The control
diet was designed according to guidelines in each participating country and provided aslightly higher proportion of calories from protein than that in the low-protein groups (19%
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Page 8vs. 17% of total energy consumed), with a glycemic index between the high-glycemic-index
and low-glycemic-index diets. Thus, the change in body weight that was observed in thecontrol group was as expected, given the protein content and glycemic-index value of thediet. Weight regain in our study was relatively low (0.56 kg), and the overall weight loss inall participants who completed the intervention was therefore quite high (10.6 kg), as
compared with the total weight loss in most studies of similar length.

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In conclusion, in this large, randomized study, a diet that was moderately high in protein
content and slightly reduced in glycemic index improved the rate of completion of theintervention and maintenance of weight loss and therefore appears to be ideal for theprevention of weight regain.

Acknowledgments
The Diogenes project was supported by a contract (FP6-2005-513946) from the European Commission Food
Quality and Safety Priority of the Sixth Framework Program. Local sponsors made financial contributions to theshop centers, which also received a number of foods free of charge from food manufacturers. A full list of thesesponsors can be seen at www.diogenes-eu.org/sponsors/.

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Drs. Meinert Larsen and Astrup report that their department, the Department of Nutrition at the University of
Copenhagen, has received research support from more than 100 food companies for this and other studies. Dr.
Astrup reports serving as an executive board member of Obesity International Trading (United Kingdom), Beer
Knowledge Institute (the Netherlands), Global Dairy Platform (United States), and Nordic Food Lab (Denmark);
serving on the European Almond Advisory Board and on the boards of 7TM Pharma, NeuroSearch, Basic
Research, Merck, Johnson & Johnson Pharmaceutical Research and Development, Jenny Craig, and Kraft; acting asa consultant or advisory board member for 7TM Pharma, NeuroSearch, Basic Research, Merck, Johnson & Johnson
Pharmaceutical Research and Development, Pfizer, Vivus, Jenny Craig, Almond Board of California, and Kraft;
and receiving lecture fees from the Almond Board of California, Arla, Campina, and Astellas Pharma. Dr. van Baak
reports receiving lecture fees from Nutrition et Santé (Belgium), and Asociación General Fabricantes de Azúcar(Spain); she also reports that her institution, Maastricht University Medical Center, received research support fromTop Institute Food and Nutrition (Wageningen, the Netherlands) and a commercial obesity treatment center, Center
for Obesity Europe (Heerlen, the Netherlands). Dr. Pfeiffer reports serving as a board member or receiving
consulting fees from Danone Medical Nutrition and also reports that his institution, the German Institute of Human
Nutrition, receives grants from Bundesministerium für Bildung und Forschung, the German Diabetes Foundation,
Bayer, and Rettenmayer and Söhne. Dr. Jebb reports serving as a board member of Coca-Cola, PepsiCo, Heinz,
Kellogg’s, Nestle, and the Almond Board of California (the fees for all board memberships are given to her
institution, the Elsie Widdowson Laboratory), receiving consulting fees from Tanita UK, and receiving payment
from Rosemary Conley Enterprises for the development of educational presentations, a magazine column, andinterviews on nutrition and weight management; she also reports that her institution receives grant support from theWorld Cancer Research Fund, Tanita, WeightWatchers, Coca-Cola, and Sanofi-Aventis. Dr. Kunešová reports that
her institution, the Institute of Endocrinology Obesity Management Center, has received support or research grants
from Unilever, Institute Danone, Milcom–Dairy Research Institute of the Federation of the Food and Drink
Industries of the Czech Republic, Novo Nordisk, Abbott Laboratories, Merck, Sanofi-Aventis, Pfizer, andSchering-Plough (now Merck). Dr. Stender reports receiving consulting fees from Novartis and Kowa ResearchInstitute and lecture fees from Merck, Pfizer, and Roche; he also reports that his department at the Gentofte
University Hospital has received payment for participation in drug trials sponsored by Pfizer, Merck, Kowa
Research Institute, Novartis, Johnson & Johnson, Cyncron, Parexel, Sanofi-Aventis, AstraZeneca, Bayer, andJanssen-Cilag. Dr. Saris reports receiving consulting fees from Nutrition and Santé (Belgium), serving on theboards of Food for Health (Ireland), International Life Sciences Institute Research Foundation (Washington, DC),
McDonalds (Oak Brook, IL), and the Institute for Cardiovascular and Metabolic Research (Reading, UK), being amember of review panels for INRA (France), Genome (Canada), and NordForsk (Norway), and being a part-time
employee of Corporate Scientist Nutrition at DSM (the Netherlands); he also reports that his institution, theMaastricht University Medical Center, receives research support from the Dutch Dairy Foundation and Novo
Nordisk.

References
1. Astrup A, Grunwald GK, Melanson EL, Saris WH, Hill JO. The role of low-fat diets in body weightcontrol: a meta-analysis of ad libitum dietary intervention studies. Int J Obes Relat Metab Disord.
2000; 24:1545–52. [PubMed: 11126204]

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2. Gardner CD, Kiazand A, Alhassan S, et al. Comparison of the Atkins, Zone, Ornish, and LEARN
diets for change in weight and related risk factors among overweight premenopausal women: the A
TO Z Weight Loss Study: a randomized trial. JAMA. 2007; 297:969–77. Erratum: JAMA
2007(298):178. [PubMed: 17341711]
3. Hession M, Rolland C, Kulkarni U, Wise A, Broom J. Systematic review of randomized controlled
trials of low-carbohydrate vs. low-fat/low-calorie diets in the management of obesity and its
comorbidities. Obes Rev. 2009; 10:36–50. [PubMed: 18700873]
4. Astrup A, Meinert LT, Harper A. Atkins and other low-carbohydrate diets: hoax or an effective tool
for weight loss? Lancet. 2004; 364:897–9. [PubMed: 15351198]
5. Eisenstein J, Roberts SB, Dallal G, Saltzman E. High-protein weight-loss diets: are they safe and dothey work? A review of the experimental and epidemiologic data. Nutr Rev. 2002; 60:189–200.
[PubMed: 12144197]
6. Halton TL, Hu FB. The effects of high protein diets on thermogenesis, satiety and weight loss: acritical review. J Am Coll Nutr. 2004; 23:373–85. [PubMed: 15466943]
7. Paddon-Jones D, Westman E, Mattes RD, Wolfe RR, Astrup A, Westerterp-Plantenga M. Protein,weight management, and satiety. Am J Clin Nutr. 2008; 87:1558S–1561S. [PubMed: 18469287]
8. Brand-Miller JC, Holt SH, Pawlak DB, McMillan J. Glycemic index and obesity. Am J Clin Nutr.
2002; 76:281S–285S. [PubMed: 12081852]
9. Thomas DE, Elliott EJ, Baur L. Low glycaemic index or low glycaemic load diets for overweight
and obesity. Cochrane Database Syst Rev. 2007; 3:CD005105. [PubMed: 17636786]
10. Livesey G, Taylor R, Hulshof T, Howlett J. Glycemic response and health — a systematic review
and meta-analysis: relations between dietary glycemic properties and health outcomes. Am J Clin
Nutr. 2008; 87:258S–268S. [PubMed: 18175766]
11. Larsen TM, Dalskov S, van Baak M, et al. The Diet, Obesity and Genes (Diogenes) Dietary Studyin eight European countries — a comprehensive design for long-term intervention. Obes Rev.
2010; 11:76–91. [PubMed: 19470086]
12. Epidata version 3 — a comprehensive tool for validated entry and documentation of data. Epidata
Association; Odense, Denmark: 2004.
13. Moore CS, Lindroos AK, Kreutzer M, et al. Dietary strategy to manipulate ad libitum
macronutrient intake, and glycaemic index, across eight European countries in the Diogenes
Study. Obes Rev. 2010; 11:67–75. [PubMed: 19573053]
14. Rasmussen LG, Larsen TM, Mortensen PK, Due A, Astrup A. Effect on 24-h energy expenditureof a moderate-fat diet high in monounsaturated fatty acids compared with that of a low-fat,carbohydrate-rich diet: a 6-mo controlled dietary intervention trial. Am J Clin Nutr. 2007;
85:1014–22. [PubMed: 17413100]
15. Skov AR, Toubro S, Raben A, Astrup A. A method to achieve control of dietary macronutrient
composition in ad libitum diets consumed by free-living subjects. Eur J Clin Nutr. 1997; 51:667–
72. [PubMed: 9347286]
16. Aston LM, Jackson D, Monsheimer S, et al. Developing a methodology for assigning glycaemic
index values to foods consumed across Europe. Obes Rev. 2010; 11:92–100. [PubMed: 20653850]
17. Gadbury GL, Coffey CS, Allison DB. Modern statistical methods for handling missing repeatedmeasurements in obesity trial data: beyond LOCF. Obes Rev. 2003; 4:175–84. [PubMed:
12916818]
18. Miller M, Beach V, Sorkin JD, et al. Comparative effects of three popular diets on lipids,
endothelial function, and C-reactive protein during weight maintenance. J Am Diet Assoc. 2009;
109:713–7. [PubMed: 19328268]
19. Skov AR, Toubro S, Ronn B, Holm L, Astrup A. Randomized trial on protein vs carbohydrate inad libitum fat reduced diet for the treatment of obesity. Int J Obes Relat Metab Disord. 1999;
23:528–36. [PubMed: 10375057]
20. McMillan-Price J, Petocz P, Atkinson F, et al. Comparison of 4 diets of varying glycemic load on
weight loss and cardiovascular risk reduction in overweight and obese young adults: a randomized
controlled trial. Arch Intern Med. 2006; 166:1466–75. [PubMed: 16864756]

N Engl J Med. Author manuscript; available in PMC 2012 May 24.

Larsen et al.

Page 10Europe PMC Funders Author Manuscripts

21. Ebbeling CB, Leidig MM, Sinclair KB, Hangen JP, Ludwig DS. A reduced-glycemic load diet in
the treatment of adolescent obesity. Arch Pediatr Adolesc Med. 2003; 157:773–9. [PubMed:
12912783]
22. Sloth B, Krog-Mikkelsen I, Flint A, et al. No difference in body weight decrease between a lowglycemic-index and a high-glycemic-index diet but reduced LDL cholesterol after 10-wk ad
libitum intake of the low-glycemic-index diet. Am J Clin Nutr. 2004; 80:337–47. [PubMed:
15277154]
23. Philippou E, Neary NM, Chaudhri O, et al. The effect of dietary glycemic index on weight
maintenance in overweight subjects: a pilot study. Obesity (Silver Spring). 2009; 17:396–401.
[PubMed: 19057524]

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Figure 1. Screening, Randomization, and Follow-up of Study Participants

HGI denotes high glycemic index, HP high protein, LCD low-calorie diet, LGI low
glycemic index, and LP low protein.

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Figure 2. Total 24-Hour Urinary Nitrogen Excretion and Changes in Body Weight

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Panel A shows 24-hour urinary nitrogen excretion, as a marker of dietary protein intake,from the time before the low-calorie diet (LCD) was initiated through the end of the weightmaintenance intervention. Panel B shows the change in weight for each of the dietary groups
during the weight-maintenance intervention, adjusted for body-mass index at randomization,weight loss during the low-calorie-diet phase, sex, family type (single-parent family, twoparent family with one parent as participant, or two-parent family with both parents asparticipants), center, and age at screening, on the basis of an intention-to-treat mixed-model
analysis. The changes in body weight from randomization to week 26 among participants
who completed the intervention are also shown (boxes). All participants who underwent
randomization and for whom data on weight at the time of randomization were available
were included. HGI denotes high glycemic index, HP high protein, LGI low glycemic index,
and LP low protein.

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548
548

Mean change during LCD phase (kg)Percent change

415

Mean change during LCD phase

415

Mean change during LCD phase

415

Mean change during LCD phase

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532

Mean change during LCD phase

530

Mean change during LCD phase

530
520

Mean

Mean change during LCD phase

Sagittal diameter (cm)

530

Mean

Hip circumference (cm)

532

Mean

Waist circumference (cm)

465

Mean

Body fat (%)

465

Mean

Fat-free mass (kg)†

465

Mean

Fat mass (kg)†

548

Mean (kg)Body weight

548

548

Age (yr)

Height (cm)

No. ofParticipants

Variable−3.2±1.7

21.9±3.6−7.5±3.7

109.2±9.6−10.5±4.6

96.8±11.8−4.9±5.1

35.9±8.4−2.5±5.2

57.2±12.6−8.9±5.6

32.1±10.0−11.3±2.9−11.3±3.4

88.4±15.7

170.6±10.3

42.2±5.7

Low Glycemic
Index(N = 106)−3.6±2.0

21.8±3.6−6.8±4.0

108.1±9.3−10.0±4.8

96.5±10.7−3.6±2.435.8±8.3−3.4±2.555.5±11.3−7.3±3.0

31.2±9.5−10.8±2.8−10.6±3.5

86.6±13.8

169.4±8.3

42.0±5.9

High Glycemic
Index(N = 97)

Low Protein(N = 203)−3.3±1.921.7±3.2−7.5±3.3

109.4±10.7−9.8±4.4

96.6±11.7−4.0±4.635.8±8.9−3.1±5.1

56.5±11.0−7.9±5.5

32.0±11.5−11.2±2.7−11.2±3.4

88.5±15.6

169.9±9.8

42.1±6.5

Low Glycemic
Index(N = 124)−3.2±1.522.1±3.9−6.9±3.9

109.9±11.1−10.4±4.6

97.6±12.8−4.6±4.735.3±8.8−2.5±5.4

58.6±13.4−8.9±5.832.2±10.9−11.2±2.4−11.2±3.1

89.5±17.1

170.8±9.6

42.0±5.7

High Glycemic
Index(N = 107)

High Protein(N = 231)−3.5±2.1

21.6±3.2−7.4±4.5

108.7±10.1−9.9±5.2

96.9±12.4−4.6±3.735.6±7.8−2.8±3.656.5±11.6−8.4±4.1

31.6±9.9−11.4±3.1−11.3±4.0

87.6±15.9

169.8±9.1

43.0±6.7

Control(N = 114)−3.4±1.921.8±3.5−7.3±3.9

109.1±10.2−10.1±4.7

96.9±11.9−4.3±4.3

35.7±8.4−2.9±4.756.8±12.0−8.3±5.0

31.8±10.4−11.2±2.8−11.1±3.5

88.1±15.7

170.1±9.4

42.3±6.1

Total(N = 548)

Characteristics of Participants at Randomization for Weight-Maintenance Phase and Changes between Beginning of Low-Calorie-Diet (LCD) Phase andRandomization for Weight-Maintenance Phase.*

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Table 1
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Fat mass and fat-free mass were assessed with the use of dual-energy x-ray absorptiometry or bioelectrical impedance analysis.

†

Plus–minus values are means ±SD. Participants were included in these analyses if they completed the maintenance intervention and if data on weight both before the beginning of the low-calorie-dietphase and at the time of randomization were available.

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intake

101

104

101

no. ofparticipants

Waist circumference (cm)Hip circumference (cm)

Sagittal diameter (cm)76

Change from screening to wk 26

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76

Change from screening to wk 26

76

Change from screening to wk 26

76

Change from screening to wk 26

76

Change from screening to wk 26

Fiber (g/day)

140

At screening

Glycemic load (g/day)

140

At screening

Glycemic index

140

At screening

Protein (% of total energy intake)140

At screening

Total fat (% of total energy intake)−17.5±62.5

138.5±53.7−4.7±7.2

60.9±5.4−0.1±5.2

18.3±5.0−7.7±9.3

37.5±7.5

8.6±9.1

42.2±8.4−2198±3761

76

140

9200±3451−0.63±6.24

0.48±7.08−0.98±4.63

140

At screening

Carbohydrates (% of total energy intake)

Change from screening to wk 26

At screening

Energy (kJ/day)†

Energy and nutrient intake

0.12±1.62

86

Fat mass (kg)0.86±2.29

86

Fat-free mass (kg)0.33±4.85

change fromrandomization
to wk 26

106

no. ofparticipants

64

141

64

141

64

141

64

141

64

141

64

141

no. ofparticipants

92

92

91

75

75

97

no. ofparticipants−21.3±65.5159.2±62.6

0.7±5.960.9±4.0−0.2±4.8

16.9±4.0−5.6±9.736.5±7.0

6.4±9.644.5±8.4−2280±3130

9924±3341

intake0.26±2.00

0.20±5.95

0.87±7.03−0.10±4.60

1.59±2.55

1.67±5.19

change fromrandomization
to wk 26

High Glycemic Index

Low Protein

Low Glycemic Index

Body weight (kg)

Anthropometric measures

Variable

98

151

98

151

98

151

98

151

98

151

98

151

no. ofparticipants

114

117

115

102

102

124

no. ofparticipants−40.4±57.2

149.3±60.3−4.3±6.7

60.8±5.2

4.5±5.1

17.2±4.1−4.5±9.836.5±7.4

0.8±10.643.8±8.5−2183±3134

9520±3186

intake−0.09±1.92−0.53±5.93−0.30±6.42−1.03±5.25

0.54±3.45−0.38±6.47

change fromrandomization
to wk 26

Low Glycemic Index

76

142

76

142

76

142

76

142

76

142

76

142

no. ofparticipants

100

100

101

87

87

107

no. ofparticipants−39.0±46.3

152.1±65.9

0±6.1

61.4±4.6

6.1±6.0

16.5±3.8−5.0±8.436.2±7.3

0.1±7.644.6±8.6−2470±2535

9471±3319

intake−0.06±2.18−0.56±5.74

1.14±6.49−0.22±5.88

1.00±4.71

0.57±5.52

change fromrandomization
to wk 26

High Glycemic Index

High Protein

79

139

79

139

79

139

79

139

79

139

79

139

no. ofparticipants

110

108

105

93

93

114

no. ofparticipants−30.4±59.6148.0±55.2−2.3±6.1

61.7±4.8

1. 8±5.0

16.9±4.4−3.7±8.937.1±7.2

3.0±8.943.4±8.6−2257±3306

9440±2914

intake0.26±2.33−0.30±5.07

0.74±5.58−0.78±4.41

1.37±3.10

0.84±4.76

change fromrandomization
to wk 26

Control

Absolute Values and Unadjusted Changes in Anthropometric Measurements from Randomization to Week 26 and in Energy and Nutrient Intake from Screening to Week 26.*

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Table 2
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76

Change from screening to wk 26

1.7±14.7

19.3±8.94141

1.6±10.4

18.7±8.2
98151
1.6±13.519.8±8.676143
0.1±7.6

18.9±8.1

High Glycemic Index

High Protein
Low Glycemic Index801390.1±11.719.5±8.0

Control

To convert the values for kilojoules to kilocalories, multiply by 0.239.

†

Plus–minus values are means ±SD. Data on the change from screening to the end of the intervention (week 26) are shown for participants who provided a complete record of their dietary intake at both screening and week 26. Further details on dietary intake are provided in the
Supplementary Appendix.

*

140

At screening

High Glycemic Index

Low Protein

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Low Glycemic Index

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Variable

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0.64(−0.16 to 1.44)

1.78(0.96 to 2.60)

Completion analysis

0.07(0.04 to 0.12)

0.07(0.04 to 0.12)

0.11(0.06 to 0.19)

0.04(0.02 to 0.07)

0.04(0.02 to 0.07)

0.05(0.02 to 0.10)

Intention-to-treat analysis

Sensitivity analysis

Completion analysis

Achievement of additional lossof >5% of body weightat randomization

2.19(1.53 to 2.85)

3.20(2.55 to 3.85)

Sensitivity analysis

Odds(95% CI)

0.69(0.18 to 1.20)

1.62(1.11 to 2.14)

kg (95% CI)

2.20(1.17 to 4.15)

1.92(1.06 to 3.45)

1.92(1.06 to 3.45)

Odds Ratio forHigh Protein vs.
Low Protein(95% CI)

1.14(0.23 to 2.06)

1.01(0.24 to 1.78)

0.93(0.31 to 1.55)

kg (95% CI)

Low Protein– High Protein

Comparison ofProtein Groups

0.02

0.03

0.03

0.02

0.01

0.003

P Value

Low Glycemic
Index

0.67
(−0.12 to 1.45)

2.20(1.55 to 2.85)

0.68(0.18 to 1.18)

0.04(0.02 to 0.09)

0.03(0.02 to 0.06)

0.03(0.02 to 0.06)

0.12(0.07 to 0.21)

0.08(0.05 to 0.13)

0.08(0.05 to 0.13)

Odds(95% CI)

1.75(0.93 to 2.58)

3.19(2.53 to 3.84)

1.63(1.11 to 2.15)

kg (95% CI)

Change in Body Weight

High Glycemic
Index

2.89
(1.50 to 5.57)

2.54(1.38 to 4.66)

2.54(1.38 to 4.66)

Odds Ratio for Low
Glycemic Index vs.
High Glycemic
Index(95% CI)

1.09(0.18 to 2.00)

0.99(0.22 to 1.76)

0.95(0.33 to 1.57)

kg (95% CI)

High-Glycemic
Index – LowGlycemic Index

Comparison of
Glycemic-Index
Groups

0.002

0.003

0.003

0.02

0.01

0.003

P Value

0.09(0.04 to 0.18)

0.06(0.03 to 0.12)

0.06(0.03 to 0.12)

Odds(95% CI)

1.66(0.67 to 2.66)

3.00(2.16 to 3.84)

1.76(1.11 to 2.41)

kg (95% CI)

Change in Body
WeightControl

The intention-to-treat analysis included all 773 participants who underwent randomization. In the sensitivity analysis, which also included all 773 participants who underwent randomization, we assumed a 1-kg weight gain per month for participants who had dropped out. The
completion analysis included 548 participants for whom data were available from both the time of randomization and the end of the trial intervention.

*

High Protein

Change in Body Weight

Low Protein

Intention-to-treat analysis

Weight regain

Variable

Weight Regain and Odds Ratios for Achievement of Additional Weight Loss of >5% of Body Weight at Randomization during the 26-Week Intervention.*

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Table 3
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