To determine energy density for rapid weight loss (RWL) of weight-classified sports, eight male elite wrestlers were instructed to lose 6% of body mass (BM) within 53 h. Energy deficit during the RWL was calculated by subtracting total energy expenditure (TEE) determined using the doubly labeled water method (DLW) from energy intake (EI) assessed with diet records. It was also estimated from body composition change estimated with the four-component model (4C) and other conventional methods. BM decreased significantly by 4.7 ± 0.5 kg (6.4 ± 0.5%). Total body water loss was the major component of the BM loss (71.0 ± 7.6%). TEE was 9446 ± 1422 kcal, and EI was 2366 ± 1184 kcal during the RWL of 53-h; therefore, the energy deficit was 7080 ± 1525 kcal. Thus, energy density was 1507 ± 279 kcal/kg ∆BM during the RWL, comparable with values obtained using the 4C, three-component model, dual energy X-ray absorptiometry, and stable isotope dilution. Energy density for RWL of wrestlers is lower than that commonly used (7400 or 7700 kcal/kg ΔBM). Although RWL is not recommended, we propose that commonly practiced extreme energy restriction such as 7400 or 7700 kcal/kg ΔBM during RWL appears to be meaningless. Nutrients Nutrients 1692 nutrients nutrients Nutrients 2072-6643 Multidisciplinary Digital Publishing Institute (MDPI) PMC5986416 PMC5986416.1 5986416 5986416 29701639 10.3390/nu10050536 nutrients-10-00536 1 Article Energy Deficit Required for Rapid Weight Loss in Elite Collegiate Wrestlers https://orcid.org/0000-0001-9145-0549 Kondo Emi 1 * Sagayama Hiroyuki 1 2 https://orcid.org/0000-0002-4284-6317 Yamada Yosuke 3 https://orcid.org/0000-0003-1089-9593 Shiose Keisuke 4 Osawa Takuya 5 Motonaga Keiko 1 Ouchi Shiori 1 Kamei Akiko 1 Nakajima Kohei 1 Higaki Yasuki 4 Tanaka Hiroaki 4 Takahashi Hideyuki 1 Okamura Koji 6 1 Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, Kita-ku, Tokyo 115-0056, Japan; hiroyuki.sagayama@jpnsport.go.jp (H.S.); keiko.motonaga@jpnsport.go.jp (K.M.); ouchi.shiori@gmail.com (S.O.); 2018 https://creativecommons.org/licenses/by/4.0/ Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( http://creativecommons.org/licenses/by/4.0/ ). To determine energy density for rapid weight loss (RWL) of weight-classified sports, eight male elite wrestlers were instructed to lose 6% of body mass (BM) within 53 h. Energy deficit during the RWL was calculated by subtracting total energy expenditure (TEE) determined using the doubly labeled water method (DLW) from energy intake (EI) assessed with diet records. It was also estimated from body composition change estimated with the four-component model (4C) and other conventional methods. BM decreased significantly by 4.7 ± 0.5 kg (6.4 ± 0.5%). Total body water loss was the major component of the BM loss (71.0 ± 7.6%). TEE was 9446 ± 1422 kcal, and EI was 2366 ± 1184 kcal during the RWL of 53-h; therefore, the energy deficit was 7080 ± 1525 kcal. Thus, energy density was 1507 ± 279 kcal/kg ∆BM during the RWL, comparable with values obtained using the 4C, three-component model, dual energy X-ray absorptiometry, and stable isotope dilution. Energy density for RWL of wrestlers is lower than that commonly used (7400 or 7700 kcal/kg ΔBM). Although RWL is not recommended, we propose that commonly practiced extreme energy restriction such as 7400 or 7700 kcal/kg ΔBM during RWL appears to be meaningless. body composition energy balance weight loss doubly labeled water multi-component model pmc-status-qastatus 0 pmc-status-live yes pmc-status-embargo no pmc-status-released yes pmc-prop-open-access yes pmc-prop-olf no pmc-prop-manuscript no pmc-prop-legally-suppressed no pmc-prop-has-pdf yes pmc-prop-has-supplement no pmc-prop-pdf-only no pmc-prop-suppress-copyright no pmc-prop-is-real-version no pmc-prop-is-scanned-article no pmc-prop-preprint no pmc-prop-in-epmc yes pmc-license-ref CC BY 1. The optimal duration of weight loss before competition is one of the major concerns of athletes, coaches, trainers, strength and conditioning specialists, and nutritional experts. The weight loss for weigh-ins for athletic competitions is sometimes associated with dehydration, resulting in dizziness, vertigo, and lightheadedness; this limits the ability to practice before the competition [ 3 ]. Several weight-classified athletes lose weight rapidly (>5%) during the final few days (2–3 days) before a competition after a long or intermediate period of mild weight loss [ 4 ]. There is limited research on criterion techniques such as the four-component (4C) or three-component (3C) models. Currently, the 4C model is regarded as a criterion method for estimating body composition. However, no previous studies have examined the change of body composition during RWL within 1 week in weight-classified athletes using the 4C model. Moreover, it is unclear regarding the change of body composition and the required energy deficit for RWL over shorter durations (2–3 days) commonly employed by many combat athletes [ 4 ]. Energy loss during BM reduction is calculated as a difference between energy intake (EI) and total energy expenditure (TEE) during BM reduction. Therefore, it is considered that despite limitations the energy balance was estimated accurately. 5. Conclusions In conclusion, we observed that the energy density of 53-h RWL was 1507 kcal/kg ΔBM. This was because the BM loss was mostly achieved by loss of TBW. Although RWL is not recommended, we propose that commonly practiced extreme energy restriction such as 7400 or 7700 kcal/ΔBM during RWL appears to be meaningless. Our findings show that the energy deficit calculated with the 4C model based on 9500 kcal/kg ΔFM and 1020 kcal/kg ΔFFM is consistent with that evaluated using TEE measured with DLW and EI under this RWL situation.