NAP: Energy Balance and Body Composition (2014)


 Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97-104. 

PubMed ID: 21558571
Study Design:
Cluster Randomized Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To compare changes in body composition, strength and power during a weekly body-weight loss of 0.7% slow reduction (SR) vs. 1.4% fast reduction (FR).

Inclusion Criteria:

 Male and female elite athletes

Exclusion Criteria:
  • Diseases and conditions known to affect metabolic functions in muscle
  • Use of pharmaceuticals that might affect any of the measurements
  • Presence of one or more of the triad components - disordered eating/eating disorder, menstrual dysfunction or low bone-bineraly density
  • Perimenopausal or postmenopausal condition
  • Pregnancy
  • Body fat less than 5% for men and 12% for women
Description of Study Protocol:


Subjects were recruited by invitation from the Norwegian Olympic Sport Center when they contacted the center to get assistance with weight loss, or by invitation letters to sport federations.


Subjects were screened and block-randomized to the SR and FR groups. They followed a 4- to 12-week energy-restriction and strength-training period. The length of the intervention depended on the subject's weight loss goal and weekly weight-loss rate.

During the intervention, all subjects continued their sport-specific training schedule. They included four strength-training sessions per week. In the first four weeks, the subjects trained with a 3 x 8-12 RM regiment, the next four weeks with 4 x 6-12 RM and the last four weeks with 5 x 6-10 RM. For subjects who participated less than 12 weeks, the program was adjusted with shorter periods.


An individualized diet plan was developed for each subject, promoting a weekly weight loss of either 0.7% or 1.4%. The aim was to have a daily intake of 1.2-1.8 g/kg protein, 4-6 g/kg carbohydrate and >20% fat, with low-energy/high-nutrient foods that provided satiety and variety. The plan included 5-7 daily meals and snacks. 

Statistical Analysis

  • The pre- to post- changes within groups were analyzed with paired-samples two-tailed Student's t test or Wilcoxon's paired-rank test when appropriate.
  • Between groups, independent two-tailed Student's t test and the Mann-Whitney test were used when appropriate.
  • Pearson's R or Spearman's rho was performed when appropriate to study correlations between variables.
  • Values of p<0.05 were considered statistically significant.
Data Collection Summary:

Timing of Measurements

Body weight, body composition (DEXA), 1-repetition maximum (1RM) tests, 40-meter sprint and countermovement jump were measured before and after intervention.

Dependent Variables

  • Body weight - measured in a fasted state with a balance scale to the nearest 100 g on the test day
  • Body composition - fat mass, percent body fat and lean body mass were measured with dual-energy X-ray absorptiometry by a trained technician
  • Performance - measured by 40-meter sprint, countermovement jump (CMJ) and 1RM of bench press, bench pull and squat. 

Independent Variables

An individualized diet plan was developed for each subject, promoting a weekly weight loss of either 0.7% (SR) or 1.4% (FR). The calculated energy deficits for the SR and FR were 469±61 and 845±113 kcal per day, respectively. The diet in both groups was a low-fat diet (~20% of total energy intake) and the mean carbohydrate intakes were 3.5±0.7 g/kg (SR) and 3.2±0.6 g/kg (FR). The mean protein intakes were 1.6±0.47 and 1.4±0.27 g/kg in SR and FR, respectively.

Control Variables

  • Post-training recovery meal
  • Multivitamin-mineral and cod liver oil supplementation
  • Weekly nutritional counseling during intervention
  • Standardized training program
  • Eating Disorder Inventory (EDI) scores


Description of Actual Data Sample:

Initial N: 30

Attrition (final N): 24 (SR = 6 male, 7 female; FR = 5 male, 6 female)

Age: SR = 24±3 years; FR = 22±5 years

Ethnicity: Not described

Other relevant demographics:

Subjects competed in the following sports: football, volleyball, cross-country skiing, judo, jujitsu, tae kwon do, waterskiing, motorcross, cycling, track and field, kickboxing, gymnastics, alpine skiing, ski jumping, freestyle sports dancing, skating, biathlon and ice hockey.

Anthropometrics: There were no significant differences between groups in any of the baseline measurements, including the EDI subscale scores.






Men (n=6)

Women (n=7)


Men (n=5)

Women (n=6)

Height (cm)






Body weight (kg)






Fat mass (kg)






Total body fat (%)






Lean body mass (kg)






Experience as athletes (yr)






Training per week (hr)






Strength training last season (hr/wk)






Location: Oslo, Norway


Summary of Results:

Key Findings

  • The weekly weight-loss rate in FR was 1.0% (compared to an initial goal of 1.4%).
  • Body weight was reduced by 5.6%±0.8% in SR (P<0.001) and 5.5%±0.7% in FR (P<0.001).
  • Fat mass decreased more in SR than in FR (31%±3% vs. 21%±0%, respectively, P=0.02).
  • Total lean body mass (LBM) increased significantly in SR by 2.1%±0.4% (P<0.01); it was unchanged in FR (-0.2%±0.7%), with significant differences between groups (P<0.01). The increase in total LBM in SR was mainly caused by a 3.1%±0.8% increase in upper body LBM. Women gained LBM while men did not (1.8%±0.4% vs. 0.0%±0.7%, respectively, P<0.01). In men, LBM was gained in SR (1.7%±0.4%, P<0.01), while men in FR tended to reduce LBM (-2.0%±1.0%, P=0.1). 
  • Performance in CMJ was improved by 7%±3% (P<0.01) in SR while no significant change was observed in FR.
  • There was no change in 40-meter sprint performance in any of the groups.
  • Squat performance improved similarly by 11.9%±3.4% (P<0.01) in SR and 8.9%±2.3% (P<0.01) in FR. Increase in 1RM squat was higher in women (16.2%±2.7%) than in men (4.7%±1.5%, P=0.002).
  • Bench press performance increased more in SR than in FR (13.6%±1.1% vs. 6.4%±3.3%, respectively, P=0.01).
  • Bench pull performance improved by 10.3%±3.0% (P=0.001) in SR and 4.0%±2.6% in FR.
  • Overall change in 1RM for upper body exercises was higher in SR than in FR (11.4%±2.6% vs. 5.2%±2.4%, respectively, P=0.03).
  • No statistically significant differences in any of the variables were found between compliers and noncompliers.
Author Conclusion:

Athletes who want to gain LBM and increase strength- and power-related performance during a weight-loss period combined with strength training should aim for a weekly weight loss of 0.7% of BW, whereas athletes who want to maintain LBM might increase their weekly weight-loss rate to 1.0-1.4% of BW.

Funding Source:
University/Hospital: Norwegian School of Sports Sciences
Norwegian Olympic Sports Center
Reviewer Comments:
  • Because many of the subjects were competing shortly after the intervention, strength training had to be included during intervention to prevent decline in performance. A cleaner approach would be to look at weight-loss rate with standardized habitual training with no additional stimuli for muscle growth.
  • Different amounts of weight lost during the intervention may also be a limiting factor. A cleaner approach would be to standardize amount of weight loss for all subjects, but this was not feasible for ethical and health reasons.


Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes