INTRODUCTION

Satiety is a determining parameter in nutrient intake control, which in the long run impacts on body weight ¹. Many athletes need strict control on their weight to achieve their aims of the season. Intense physical exercise temporarily causes ingestion reduction that is accompanied characteristically by physical exercise with the aim of defending the organism against metabolic stress caused by an increase in nutrient demands ^2,3.

Appetite is only a part of ingestion behaviour that has many aspects. A sociocultural dimension exists given that people normally eat in groups and all the process is subjected to a circadian rhythm. In this way, although daily energy use isn't measured consciously and varies in function of physical activity, climate and other factors, appetite adjusts to necessities, maintaining stable body weight ⁴.

The need and wish to fill oneself that is complemented with the added value of pleasure as a consequence of an act of consuming, is produced in neuronal networks that extensively overlap. The pleasure system is associated to cerebral structures that generate consumerist acts. The bases of all of these are the survival mechanisms, where decisions are taken to cover vital needs. Eating is one of these needs. However, since some decades ago, in developed countries, humans maintain a normal weight within strict limits, this is because of a homeostatic process that the organism has ⁵. When eating starts, the balance between hunger and satiety depends on numerous factors, such as emotional, the time of the day, the hedonic value of foods, social uses, etc. All of this, mostly, escapes homeostatic energy control, allowing us to eat even in absence of the sensation of appetite. However, the instant when ingestion finishes seems to be biologically more controlled, thanks to the mediation of nerve and hormonal signals called by satiety ⁶. As a result, the nervous system intervenes in the emergence of satiety, advancing or retroceding it and can affect the magnitude of meals and in this way, the quantity of energy consumed. In this manner, the regulation of food intake in the long term is assured by the adjustment of control in short term. For this reason, hunger and appetite and the sensations that they transmit are the episodes in which the organism searches, chooses and ingests food and the phenomenon's that provisionally finalize with ingestion and procure the sensation of satiety ⁷.

At an intracellular level, the metabolic pathways benefit from the nutrients provided as a result of ingestion that trigger satiety signals. In the homeostasis of the metabolic pathways, the role of certain enzymes is highlighted so that when resting they stimulate the thermogenesis process or use nutrients in a more efficient way when doing an activity ⁶. Here the involved signals play a leading role in the homeostasis of fatty tissue, like leptin, that is a small circulating peptide secreted by the white adipose tissue, whose synthesis increases when fat mass increases in the organism ⁸.

Altered psychological states like depression or anxiety are related with abnormal food behaviours, affecting appetite in a great manner and the choice of food. In this way, according to pretensions at psychological or negative emotional levels or anguish, an increment or decrement of ingestion of food or control of satiety can be activated ⁹.

In this way, in athletes, the event of a sporting challenge influences in the psycho-physiological state of the athlete ¹⁰. Intrinsically, it can mean threatening aspects that can convert into a challenge for athletes ¹¹ and the levels of anxiety can increase before sporting events. Anxiety has been considered a negative emotional state ¹² as a discouraging emotional reaction that accompanies the arousal of the autonomous nervous system and considered thereby as a dis-adaptive emotional condition. This is a multidimensional construct that is constituted of different components, making a difference between intensity and directionality of anxiety ¹³, and somatic and cognitive anxiety.

A nutritionally inadequate diet or an adequate control in the diet intake of athletes can also affect processes related with the ingestion of foods and thus, satiety ¹⁴. Recent studies show a relation between alterations in food behaviour and the presence of anxiety ^15,16. In this regard, an increase in ingestion of ad libitum foods, in absence of hunger, is related with an increment of body weight ¹⁷. In terms of sport contexts, an increment of weight at the cost of fat mass, will impact negatively in the performance of athletes during sport practice ¹⁸.

Overall, the aim of this study is to determine the influence of satiety on anxiety and body weight control in a university athlete population comparing them in two groups, those that followed a free diet ad libitum and those that followed a supervised nutritional program in order to reach the correct weight. The hypothesis of this study is that satiety plays a determining role in the control of body weight in sport, for this reason, it will be adequate establish dietetic strategies to permit the subjects manage this sensation without generating anxiety states, allowing better control of body weight long term.

METHODS

RESULTS

All participants included in study, followed the intervention protocol, assessments and concluded each stage of our study. When comparing both groups of athletes, significant differences were observed between both in the variation of weight (p = 0.004), where the SATIETY group incremented their weight whilst the DIET group decreased. Although no significant differences were found, the DIET group showed an increase in muscle mass accompanied by a decrease in fat mass, in absolute values (kg) and in relative values (%), contrary to the SATIETY group (Fig. 1). The anxiety results (Fig. 2), found significant differences between both DIET and SATIETY groups in the POST CS intensity values (p = 0.040), where the DIET group has higher SC values. Regarding significant differences (p = 0.043) between the SA intensity between the two groups, the DIET group showed a fall in the SA levels whilst the SATIETY group increased these levels at the end of the study.

Figure 1 Body composition assessment PRE and POST intervention on DIET and SATIETY groups (*pvalor < 0.05; differences between DIET and SATIETY groups; **pvalor < 0.05; differences between PRE and POST evaluation into the same group). 

Figure 2 Competitive anxiety assessment: Competitive State Anxiety Inventory-2 (CA: cognitive anxiety; SA: somatic anxiety; SC: self-confidence; DIR: directionality; INT: intensity). 

On one hand, when comparing the subjects within each of the groups, the DIET group before and after the intervention, have shown a significant decrease in both total body weight (p = 0.016) and fat mass in absolute (kg) (p = 0.045) and relative (%) (p = 0.044) values (Fig. 1) with moderate ES. However, in the rest of the studies variables there were no significant differences.

On the other hand, the SATIETY group also presented significant differences in the total body weight (p = 0.046), having incremented after the intervention (Fig. 1). Also, significant differences were found in the SA intensity (p = 0.031) and the CA directionality (p = 0.033), producing in both a significant post intervention increase, both with moderate ES (Table I).

Table I Difference between both values (∆ = POST - PRE) indicated the variation in body composition assessment or competitive anxiety of each group during the study 

After making correlations between the different variables in both groups, the DIET group showed a significant correlation between the increment of fat mass percentage and CA intensity (R = -0.612; p = 0.046), the lower the muscle mass increment, the higher the CA intensity in the DIET group. In the rest of the variables, no significant differences were found. Furthermore, in the SATIETY group, significant correlations were observed between the increment of muscle mass and the CA directionality (R = -0.715; p = 0.020), in percentage (R = -0-72; p = 0.017) and also the CA directionality, in this case in a negative form.

DISCUSSION

Body weight is a determining parameter in sport performance. Achieving an optimal weight for a better adaptation to sport isn't an easy task. Diets don't seem to achieve the desired results, although they seem to be well designed, they generate anxiety states in the subjects, especially if they have to lose weight. Moreover, many sport groups lack professional services to plan correct diets.

Even though, in the present study no significant differences have been highlighted, it seems that the DIET group has an increased predisposition in exhibiting modification in body composition that favours sport performance. The obtained results show that following an adequate, individualized nutritional dietary programme that is adapted to each athlete, helps them to decrease their weight in a significant form compared to those who ingest food freely. This fact coincides with the importance of satiety control to control body weight ^1). Also, this weight reduction influences on fat mass in a significant form without muscle mass being affected in the DIET group.

In the SATIETY group, the results obtained from an increment in the SA intensity could be due to the fact that the subjects are conscious that they probably haven't used the most adequate nutritional dietary strategies to achieve an improvement in their body composition and sport performance, as they have had no limits when ingesting food along the day. For this reason, it is necessary that athletes follow an adapted diet to their particular energetic needs, so that they can replace lost energy through exercise, however, without exceeding the replenishment as this increments total body weight, as seen in the results of this present study; as an increment of weight that isn't exclusively of muscle mass will negatively impact on sports performance.

In this way, it seems that in the sample of studied athletes, appetite can be altered by energetic needs and body weight isn't always maintained, in opposition to other studies ^4,5. Likewise, it is necessary to highlight the influence of psychological aspects as a conditioning factor of satiety mechanisms ⁹.

The results obtained in the correlations of the DIET group, reveal the importance of body composition values regarding the CA intensity level. Furthermore, regarding the correlations of the SATIETY group, it seems that as the body composition improves in relation to muscle mass and fat mass parameters, the CA directionality increments favourably which benefits sport performance ²⁸. In this regard, the athletes show at cognitive level that a favourable body composition is favourable when doing sporting events.

It seems evident that anxiety is a factor that influences on sport performance ²⁹. However, there are many theories that associate different parameters of anxiety with opposite effects on performance. The first tendencies focused on decreasing anxiety and increasing SC to achieve higher sporting success ³⁰. In our study, after the intervention, the DIET group achieved higher SC intensity levels than the SATIETY group, which could be because the nutritional dietary strategies help athletes to cope with ease the sporting challenge in question, also having a higher control at cognitive level of their own possibilities and confidence in their abilities. The differences between the DIET and SATIETY groups in relation to the increment of the SA intensity, highlights that those athletes that don't control their diet show a series of impacts at a psychological level, that can influence at a physiological level like tension increments at muscle level, stomach upsets and increases in sweating and heartbeats ³¹.

It has been proven that stressful situations or anxiety states can affect our food behaviours, influencing in the choice and ingestion of food, like in satiety mechanisms. Moreover, it seems that elevated anxiety levels, seen in the SATIETY group in the current study, also corresponds with an excess of food intake, equally seen in other scientific studies ⁹.

The fact that no significant differences were found in the different fat and muscular compartments of the body composition between the studied groups could be due to the reduced number of the sample and differences between athletes in metabolism and exercise adaptations. Because of these limitations, the need to do an intervention incrementing the number of athletes and the control of metabolic parameters in both DIET and SATIETY group is highlighted. In this way, other limitation of this study was the absence of gas analyzer to measure oxygen uptake to assess the energy cost (METs), and data could be converted to units of energy expenditure (METs). Furthermore the control of body composition by DXA and blood biomarkers could also provide complementary information. Also, it could have been interesting to do specific tasks that assess physical performance, like exercise tests that are useful for objectively evaluating body composition changes with the intention of correlating them with better performance. However, these tests were not done in the present study.

In conclusion, athletes that followed a specific nutritional dietary programme show favourable modifications in body composition without showing higher levels of competitive anxiety. A diet without controlling satiety mechanisms could produce an increment in competitive anxiety.