###### Abstract  
Physical activity has been instrumental in shaping the human body throughout evolution, but modern sedentary lifestyles and excessive caloric intake have contributed to chronic diseases. This study investigates the potential benefits of recreating the hunter-gatherer lifestyle, involving physical activity and caloric restriction on psychophysiological responses. The aim is to understand the evolutionary disparities between ancestral and modern lifestyles. Two male participants, one fasting and one control, were analyzed during a 4-day walking event without caloric consumption. Psychophysiological parameters such as body mass, cortical arousal, hand-grip strength, lower limb strength, heart rate variability, reaction time, hydration status, blood glucose and lactate levels, urine markers, sleep quality, pain perception, stress levels, and perceived exertion were measured. The fasting participant exhibited higher ratings of perceived exertion, stress, pain, and dehydration. They also experienced poorer sleep quality, higher Creatinkinase levels, greater protein presence in urine, decreased lower limb strength, significant weight loss, and increased lactate values. Heart rate variability did not differ significantly between the fasting and control participants. Recreating the hunter-gatherer lifestyle through physical activity and caloric restriction can have implications for enhancing performance and improving overall health. However, further research is needed to better understand the complex interplay of factors involved in the psychophysiological responses to such interventions. hunter-gatherer lifestyle; physical activity; caloric restriction; psychophysiological response; evolutionary disparities +
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their genes [3]. Studies on various animal models have demonstrated that caloric restriction can extend lifespan and enhance metabolic health [4]. Although the evidence regarding the role of caloric restriction in human evolution remains speculative, some research suggests its influence in shaping the human body and metabolism over time [3]. [PERSON] et al. 2016 indicated that humans are the only animals consuming energy without prior expenditure, violating the biological laws [5]. In comparison to our ancestors and other animals, modern humans consume significantly more energy without requiring commensurate physical exertion. The prevalence of highly processed foods and reduced physical activity resulting from technological advancements and urbanization has led to excessive energy consumption without proportional physical expenditure [6]. This form of energy surplus has been associated with various health problems, including weight gain, obesity, cardiovascular diseases, and type 2 diabetes [7; 8]. As hunter-gatherers, our evolutionary ancestors experienced fixed-length hunting periods marked by physical activity and caloric restriction. The duration of a hunt varied depending on factors such as the animal's size, the number of hunters involved, and the hunting techniques employed. Some hunts could last several hours or even days, with the Kalahari bushmen known to pursue antelopes for hours, covering distances exceeding 30 km before successfully capturing the animal [9]. Consequently, numerous disparities arise when comparing the modern lifestyle of humans with that of our evolutionary ancestors. Our ancestors engaged in physically demanding tasks such as hunting, gathering, and farming for survival, while many individuals in modern society lead sedentary lives, spending a significant portion of their time sitting or engaging in minimal physical activity [10]. Additionally, our ancestors adhered to a different diet compared to most people today, primarily consisting of whole foods and periods of caloric restriction, whereas modern diets often revolve around highly processed and calorie-dense foods [11].