Obesity and COVID-19

Context: The emerging disease COVID-19 has made a major problem for people around the world, and treatment systems are facing hardships. Obesity is a risk factor for health, and COVID-19 is a global disease. Obesity may be a risk factor for this disease. The relationship between obesity and the disease was examined in this study. Evidence Acquisition: Three databases, PubMed, Scopus, and Embase, were examined. The search strategy and keyword combinations were (“COVID-19” OR “Coronavirus” OR “Wuhan virus” AND “Obesity” OR “Obese”). The results of related articles were used. Results: Obesity, diabetes, hypertension, cardiovascular, and respiratory diseases are the risk factors for COVID-19, especially in severe cases, which can affect the length of hospital stay and mortality. Conclusions: We know very little about this disease. Thus, much research is needed to conduct. Since obesity is a risk factor for this disease, exercise is proposed to prevent it.

19 patients, visceral adiposity or high intramuscular fat deposition increases the risk for critical illness.
The contribution of obesity to the severity of COVID-19 may be explained in multiple ways. Obesity is a well-recognized risk factor for diabetes, hypertension, and cardiovascular disease, all of which are predictors of poor outcomes in COVID-19 (12). Obesity may also impair immune response to viral infections and affect diaphragm excursion (thus causing dysventilation) (3,13). Additionally, the management of obese patients with COVID-19 might be more challenging than routine because the patient's size may limit medical and assistive procedures.
Furthermore, obesity is characterized by abnormal secretion of adipokines and cytokines determining a low-grade systemic inflammation, which may represent the background predisposition to the most severe consequences of COVID-19 (3). At the same time, chronic low-grade inflammation represents a hallmark of aging, responsible for altered metabolism (i.e., elevation of resting energy expenditure) and increased muscle catabolism (14,15). Inflammation could be the key factor of the muscle decline observed in older individuals, which can be further exacerbated in those with obesity (16). Obesity may also lead to increased fat infiltration of the muscle associated with a decrease in muscle strength and function, mainly due to physical inactivity of obese individuals. As a consequence, muscle decline may lead to a decrease in physical activity, which, in turn, promotes obesity with consequent increased catabolism and anabolic resistance, thus creating a vicious circle of muscle decline (17). In fact, fat mass increase usually precedes a loss of muscle mass. In other words, the increase of adiposity (especially in visceral fat) along with the low-grade chronic inflammation seen with aging could have even more detrimental effects and determine an accelerated muscle decline. Interestingly, intermuscular adipose tissue is shown to contribute to physical impairment, enhancement of insulin resistance, and increased the risk of negative health-related events (18).
In this global pandemic, the negative effects of obesity are not confined solely to the acute care setting. In fact, the need for social distancing and isolation during the lockdown may exacerbate depressive symptoms. Furthermore, self-isolation may increase the barriers to accessing healthy and fresh foods with a net shift toward convenience foods, especially in people with a poor socioeconomic status. The self-isolation period due to the lockdown may also lead to the deterioration of the circadian rhythm, resulting in a change of eating habits. Obesity has been widely related to sleep alteration and vice versa (25). In fact, sleep disorders can result in metabolic (i.e., decreased glucose tolerance and insulin sensitivity) and endocrine alterations (i.e., reduced leptin levels, high evening concentrations of cortisol, ghrelin, and increased hunger and appetite), all of which promote obesity (26). Sleep disturbances may also result from high circulating levels of pro-inflammatory cytokines, which are a hallmark of obesity (27). Additionally, high-fat and high-carbohydrate meals may alter sleep indexes (26)(27)(28)(29) via the elevation of the circulating levels of glucose, insulin, leptin, cholecystokinin (CCK), peptide YY, and enterostatin (28)(29)(30).
On the other hand, it should not be neglected that obese individuals may suffer from stigma and depressive symptoms already in normal times. This may render them more likely to restrict their social contacts with detrimental consequences to their physical and psychological domains in the period of COVID-19 (31).
In conclusion, it is necessary that special attention is paid to prevent and control the COVID-19 infection in specific populations, such as obese and older persons, who are already exposed to basal inflammatory status. Inflammation, which is a hallmark of both obesity and the aging process, might have a synergistic role in promoting greater severity of COVID-19. However, as discussed, obesity measured with BMI does not necessarily reflect adiposity. Indeed, it is important to bear in mind that even though the box may look the same, the contents may be different. In this case, it would be better to think inside the box. The role of obesity in COVID-19, given the burden it poses, must no longer be ignored and may have major implications in the public health strategy.

AUTHOR CONTRIBUTIONS
DA contributed to conceptualizing and writing the manuscript. MC edited and revised manuscript. DA and MC approved the final version of manuscript. All authors contributed to the article and approved the submitted version.