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).

 Male and female elite athletes

• 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

Recruitment

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.

Design

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.

Intervention

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.

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

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.

Location: Oslo, Norway

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.

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.

• 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.