How obesity and fitness affect human life

There is increasing evidence to support that both fitness levels and fatness levels are related to the current and future health status of individuals. In this article, we discuss the importance of fitness and fatness/obesity and review what is currently known about fitness and fatness as potentially modifiable risk factors for health and disease from preschool children to older adults. We describe the methods available for assessing fitness in each age group and provide reference/criterion values ​​where available. Most of the existing previous reviews are focused on specific age groups, with the advantage of allowing a deeper analysis of the evidence, but the disadvantage of losing the overall understanding of the binomial of fitness and fatness over the human lifespan, which is the ultimate goal of this article. Keywords: Physical fitness, cardiorespiratory fitness, obesity, obesity, health, preschool, children, adolescents, adults, older adults Introduction A person's level of physical fitness (henceforth referred to as fitness) and the amount of adipose tissue accumulated in the body (henceforth referred to as fat) have been shown to be strongly associated with many and varied health outcomes.[1–4] Although previous reviews have focused on specific age groups, we aim to present in a single document, an overview of the health relevance of both fitness and fat throughout life (Fig. ​ (Fig.1). 1 ). In addition, we aim to briefly describe the methods available for assessing fitness in each age group and provide reference/criterion values ​​where available. For this article, we have assembled a group of experts with long-term and extensive experience in fitness and fatness in some of  the age groups studied so that the writing group can cover the topic with expertise across the human lifespan.Body fat and obesity are most often used as synonyms in the literature and refer to the state of excess adipose tissue in the body, which is associated with poorer health. Although obesity is generally understood as excess body fat, it is internationally and well accepted as a high body mass index (BMI), i.e. equal to or greater than 30 kg/m2. Thus, there is a discrepancy between the term (excess fat) and the most widely used index for measuring and defining obesity, high BMI, which indicates excessive body weight normalized for height. Reasons for BMI being more commonly used than body fat indices to define obesity are likely to be that measuring BMI is simpler, requires less expensive equipment and training than body fat indices. However, there is a general belief that BMI is a proxy for the amount of adiposity and that a more accurate metric of body fat such as body fat percentage (BF%) or fat mass index (FMI, fat mass expressed in kilograms) is used whenever possible. divided by the square of height in meters) should be used to define obesity and to study the relationship between obesity and healthFitness is a strong indicator of health in children and adolescents[6] and there is no reason to believe that fitness is less important in preschoolers. We systematically reviewed the existing literature on the validity, reliability, and relationship to health of aptitude tests used in preschool children. This systematic review concluded with the design of a battery of fitness tests for preschoolers (ages 3–5) called the PREFIT (Preschool FITness Assessment) battery.[7] Contrary to other age groups, CRF was the least investigated component of fitness and the most was balance.