The results of our study suggested that elite Greco–Roman wrestlers who followed a dietitian-supported personalized balanced diet during the three-week camp period had decreased body weight, BMI, skin fold thickness, body fat and FM, and urine density and demonstrated a positive change in mood profiles (a medium to large magnitude of effect) compared to the controls who followed the traditional method. Moreover, the change in the macro- and micro-nutrient intake was more balanced in favor of the experimental group.
The approximate weekly weight loss of athletes during short periods was reportedly 3–7 kg [24]. At the beginning of the study, the body weight of the athletes in both the groups was found to be similar and exceeded the targeted weight (by 3.5–4.5 kg). Athletes who received dietitian support lost more weight and attained a weight that was very close to the target weight in the competition (− 0.25 kg). Athletes who did not receive dietician support failed to reach their target weight by an average deviation in weight of 2.12 kg. This result is suggestive of the importance of seeking dietitian support in cases where weight should be lost over a relatively short period among athletes.
Excessive training during the pre-competition period is a traditional method that is followed to ensure RWL among athletes. Cutrufello et al. [25] reported that male wrestlers might lose 1.5 ± 0.2 kg of body weight after 2 hours of wrestling training [24]. However, it was also reported that the acute weight loss that occurs following training prior to the weigh-in on the day of the competition was attributable to fluid loss and was an unhealthy method for RWL [24]. It is a remarkable result of our study that although all the athletes underwent the same training program, those that received dietitian support achieved better results with respect to achieveing their target weight based on the weight class. Athletes in the control group, which did not receive dietitian support, did not achieve the target wight based on their weight class, despite visiting a sauna and undergoing extra training in thick clothes before the weigh-in. These results are consistent with the results of studies [24] that suggested that RWL was often sought through traditional methods prior the competition in the combat sports and athletes participating in competitions that necessitate the use of weight classes. Furthermore, it was also emphasized that upon RWL, the athletes might not be able to attain replacement in terms of energy and fluid over a short duration and that their performance might be adversely affected [26]. Ultimately, it was suggested that following a weight-control method spanning the entire duration of the annual training period under the supervision of a dietitian would be much more useful for maintaining the athletes’ health and improving their performance.
With regard to sports performance, body composition characteristics constitute the primary factor in the development of conditioning programs during the competition season [27]. In the present study, the group that received dietitian support had a higher decrease in skinfold thickness as well as in the fat percentage (− 1.01%) compared to the group that resorted to the traditional method. Studies on elite athletes reported a body fat percentage range of 7.4–13% [28, 29]. The weight classes, age categories, and measurement methods may account for the differences in the distribution reported by relevant studies. In the present study, the fat percentage values varied across a wide range owing to weight class differences (8.88–30.98%). On the other hand, the average fat percentage values of the athletes in both the groups were similar to the results reported in similar studies [28, 29].
Some of the RWL owing to high amount of energy restriction may manifest in the form of FFM [30]. In the present study, the average decrease in FFM level (kg) in both groups suggested that athletes might have undergone RWL over a short duration. Nevertheless, it is remarkable that there was an increase in the percentage of FFM in parallel with the decrease in fat weight in the experimental group compared to the control group. The FFM rate of the athletes who received dietitian support increased (1.04%), whereas the same slightly decreased in those who did not receive support. In similar studies, the FFM rate in athletes who lost weight gradually by means of a nutrition program increased by 2% in 20 days [31] and by 2.98% in 6 weeks; [32] these results are consistent with the results of our study. Although it is possible to lose FM while potentially maintaining the FFM, the intervention must comply with scientific dietary guidelines [30]. Slower weight loss will help better maintain the FFM in athletes. However, it was reported that a protein-rich diet (1.6 to 2.2 g/kg/day) might reduce the FM, while maintaining the FFM [33].
It was reported in a study with young elite athletes that the average daily energy intake was 4958 kcal during the period without any attempt to lose weight [34]. In the weight class sports, the daily energy consumption of athletes decreases during weight reduction periods compared to the normal periods [31, 35]. The daily energy consumption of both the groups of athletes was decreased to induce a change in body composition during the study period; this indicates that the restriction on the energy consumption of athletes who lose weight without dietitian intervention is greater than that of athletes under dietician supervision and that traditional methods fail to regulate energy intake in a balanced manner.
Proteins, carbohydrates, and fats, i.e., the macronutrients required to provide energy on a daily basis, are especially important in meeting the daily energy needs among athletes. The carbohydrate consumption among athletes was suggested to be within the range of 3–4 g/kg prior to performing short-term high intensity exercises [34] and 5–7 g/kg pior to performing medium intensity exercises [36]. Furthermore, a review of the published guidelines on the nutrition of athletes indicated that carbohydrate consumption between 3–12 g/kg was necessary [11]. In our study, the energy and nutrient (carbohydrate, protein, and fat) consumption of the athletes included in the experimental group was planned considering their body weight. The pre- and post-test carbohydrate consumption of athletes in the experimental group was 4.24 g/kg and 3.31 g/kg, respectively, and these values were considered to be sufficient for high intensity short-term exercises. In contrast, the mean pre- and post-test levels in the control group were 4.56 g/kg and 2.28 g/kg, respectively. In a study that ensured a weight loss of 6% over a 3-day period, Kondo et al. found that the athletes had a carbohydrate intake of 6.9 ± 1.9 g/kg during the normal period and 2.1 ± 1.0 during the weight-control period [35].
A protein intake of 1.2–1.7 g/kg was suggested to be sufficient for athletes, whereas in cases where energy is restricted for weight loss purposes, an increase in the same to 2.0–2.5 g/kg was recommended [36]. Published guidelines generally recommend that protein consumption should range between 1.2–2.0 g/kg [11]. The daily protein intake of the athletes in both the groups was similar and within the recommended range (1.2–2.0 g/kg) at the beginning of the present study [11]. However, the significant decrease in the post-test protein levels in the control group compared to that at the beginning of the study (1.3 g/kg) might be attributable to the subconscious weight loss program without dietitian intervention followed by the athletes in this group. The protein intake was 1.7 ± 0.4 g in the normal period compared to 0.5 ± 0.2 g during the weight loss period among the athletes, who lost 6% of their body weight in 3 days by following traditional methods for RWL [34]. The radical decrease in protein intake reported in the study by Kondo et al. might have been attributable to the short duration of the weight loss period [35]. In the present study, the decrease in protein (g/kg) consumption in the experimental group was lower compared to that in the control group. This is indicative of the fact that a qualified nutrition program under the supervision of a dietitian will ensure that even the decreases in macronutrient consumption occur in a controlled manner. Moreover, the macronutrient intake of the group that received dietitian support appeared to be in line with the current sports nutrition guidelines [11].
In our study, the decrease in the fat (g/kg) intake (78.1%) in the group of athletes who received dietitian support was higher compared to that in those who did not receive support (54%), but this decrease was within the recommended daily limits for athletes.
An assessment of micronutrients consumption showed that all except for vitamin D and potassium were compliant with the TÜBER 2015 reference values in the experimental and control groups (vitamin D (15 µg-400 IU), potassium (4.7 g/day)) [12]. The fact that the potassium intake of the control group was lower compared to the reference values at the end of the camp may be attributed to the imbalances in the energy intake.
One of the irrational nutrition strategies that athletes follow to meet the requirements of the weight class is to significantly reduce fluid intake few days before the competition. In our study, the fact that the duration and frequency of training conducted 1 week before the competition was decreased by half compared to the pre-test values may account for the fact that water consumption was decreased in the athletes from both groups as observed during the post-test evaluation. In our study, the fact that the water consumption of athletes who received dietitian support was lower compared to that at the onset of the study, but higher compared to the control group ensured that the urine density was maintained at optimal levels. Relevant studies that investigated hydration on the basis of urine density on the day of competition in athletes participating in competitions requiring weight classes reported that the hydration status was impaired in groups that lost weight by following traditional methods [37]. The fact that better hydration conditions are associated with higher muscle contraction time in athletes can also have a positive impact on the performance [38]. Another important finding of the present study is that upon the post-test hydration measurements, 25% of the group that lost weight without dietitian support had hypo-hydration and 75% had severe hypo-hydration, whereas all the athletes who received dietitian support during weight loss were within the normal hydration range. These results are suggestive of the fact that the qualified nutrition programs implemented with dietitian support contribute to the healthy control of dehydration in athletes, especially when RWL is required.
There are a number of studies in the relevant literature that investigated the relationship of mood profiles with RWL among athletes across different sports [7, 39, 40]. These studies suggested that RWL caused short-term memory loss, decreased concentration, and increased anger, fatigue, and depression scores among athletes [38]. It was reported that an average of 5% RWL in boxers and judokas was associated with increased anger, fatigue, and tension scores, and weightlifters also had depression in addition to the above manifestations [7]. Negative emotions, including anger, fatigue, tension, depression, and confusion may increase after exercise or RWL over a short period [39]. In the present study, dietitian support had a positive effect on the mood profile of athletes.