Journal Title (Medline/Pubmed accepted abbreviation): Intl. J. Sport. Nutr.Exerc.Metab.
Page Numbers: 426-435
Summary of background and research design:
Background: Weight loss is desired by some elite athletes for a variety of reasons. The current recommendation is to lose no more than 0.5-1.0 kg per week (about 1-2 lbs) in order to maintain lean body mass and performance in the sport.
Hypothesis: Athletes that lose weight at 0.5 kg/wk compared to those that lose 1.0 kg/wk will maintain body composition and performance on selected activities [ex. 1 repetition maximum (RM) on bench press].
Subjects: Athletes age 18-35 y were recruited from the Norwegian Olympic Sport Center representing 19 sports. Out of 36 recruited, 30 completed the weight-loss intervention and 23 completed the 6- and 12- month post-tests. Men were about 11-14% fat initially whereas women were about 18-20% fat.
Experimental design:randomized blockTreatments:
Weight reduction at 0.7% mass or 1.4% mass per week
Protocol:Athletes were randomized to the slow or fast weight loss protocols. Nutritional plans were provided by nutritionists on staff. The duration of their weight loss intervention was based on their individual goals. Body mass, body composition (fat mass and lean body mass using DEXA), and indicators of performance (40 m sprint, counter-movement jump, and 1 RM bench press, bench pull, and squat) were assessed before the weight loss intervention as well and 6 and 12 mos later. Also, a questionnaire was completed by the athletes at the same time points to assess eating behaviors and attitudes toward food in order to identify potential eating disorders.
Summary of research findings:
- Average energy intake was decreased 31 ± 5% in the fast weight loss group and 19 ± 5% in the slow weight loss group during the intervention.
- Many athletes did not comply completely with the diet plans during or after intervention.
- On average, body mass was reduced by 5.8 ± 0.7% by those in the slow weight loss group and 5.7 ± 0.9% in the fast weight loss group, indicating that both diet plans were equally effective.
- Individuals on the slow weight loss had greater fat losses than did the fast weight loss group (31 vs. 23%), but also regained fat faster in the 6-month period after the weight loss was achieved.
- At 12 mos after the weight loss intervention athletes in both groups regained the lost fat mass.
- Sprint and countermovement jump were not included in the analysis due to a low number of participants that completed these activities due to injuries. There were no changes in performance on any of the selected activities for the fast weight loss group. Average 1 RM increased after the intervention for those in the slow weight loss group but performance returned to baseline 6 and 12 mos after intervention.
Key practice applications:
This study was limited in that many athletes did not comply with the diet and/or did not complete the entire experimental protocol. With that said, the athletes in the slow weight loss group gained the weight back faster than those in the fast weight loss group yet maintained performance gains better than those in the slow weight loss group. Both of these diets were within the generally accepted weight loss recommendations for 0.5-1.0 kg/wk.
An unofficial key practice application from this study is that it was very difficult for elite athletes to lose fat mass and keep the weight off. These athletes are training for the Olympics, are some of the most dedicated athletes in the country, and had personal goals to lose weight, yet did not meet their goals. It would be interesting to look into the reasons why this population found weight loss difficult. Were their body types already optimized for peak performance and, thus, weight loss was impractical? Were short -term performance metrics chosen to not be compromised by the inevitable discomfort/lack of energy associated with weight loss? Are their reasons equivalent to non-athletes?
The authors recommend that, if athletes aim to lose weight, that weight loss should be achieved on the off-season through a moderate-energy restriction diet with high amounts of nutrient-dense foods. Weight loss through dehydration, vomiting, and laxatives can negatively affect performance and should never be implemented.