Abstract
Both global and US data show associations between COVID-19 death rates and overweight or obesity, which are also risk factors for several other outcomes. Evidence suggests that among the strategies to reduce overweight and obesity are the simple actions of increasing fruit and vegetable consumption and physical activity. Potential benefits include saving thousands of lives and billions of dollars in a future pandemic and reduced risk of other chronic conditions.
Once transmission of COVID-19 expanded beyond Asia, the role of cardiometabolic risk factors and especially overweight and obesity, became clear. 1 With early data coming from China where obesity rates are low, obese adults were not a group with reported high COVID-19 hospitalization or death rates. Early hospitalization data from the US found that adults with hypertension (49.7%), obesity (48.3%) chronic lung disease (34.6%), diabetes (28%), and cardiovascular disease (27.8%) were disproportionately represented among those hospitalized with COVID-19. 2 Another US study limited to cardiometabolic conditions found similar but somewhat lower rates of hospitalizations among those with obesity (30.2%) hypertension (26.2%), diabetes (20.5%) and heart failure (11.7%). Estimates of the percentage of adults with increased risk of hospitalization and death from COVID-19 found that the 5 conditions 2 included 56.0% of all US adults. 1
Further evidence of the significance of obesity in the risk of complications from COVID-19 comes from the World Obesity 4 Federation (WOF), which showed that in countries where the prevalence of overweight is >50%, the death rate from COVID was about 10 times that in countries where overweight was less prevalent. Results showed a nearly flat line for deaths vs overweight for countries with overweight <50%, with the slope rising dramatically above 50%. The US, with an overweight prevalence of 67.9%, had a death rate 23.5 times that in countries with overweight <50%. Using more recent data5,6 and obesity instead of overweight, results are similar with the rise in deaths occurring at about 15%, again with a nearly flat line below 15%. A study of 30 industrialized countries 7 found that along with obesity, other factors including population density, the age structure of the population, population health, GDP, ethnic diversity, and how the pandemic was handled were also associated with COVID death rates. That model explained 63% of the intercountry variation in COVID death rates. The findings by the WOF 4 suggest that 90% or more of the COVID-19 deaths in the US might have been prevented if our overweight prevalence was below the 50% threshold. They also note that COVID-19 is not a special case and that we should expect the next pandemic to have similar associations between overweight/obesity and deaths.
Obesity and overweight were also associated with COVID deaths within the US, with the associations less striking than global differences, but still statistically significant. 8 Data on obesity and overweight are from the 2019 Behavioral Risk Factor Surveillance System (BRFSS) and the number of deaths/million were assigned to the state in which the survey respondent resided. 9 Mean number of state COVID deaths through July 29, 2021 8 for obese respondents was 1804 (95% CI 1800-1807) vs 1795 (1793-1797) for respondents who were not obese and for overweight and non-overweight respondents the corresponding figures were 1800 (1798-1802) and 1793 (1790-1797).
Obesity and overweight are among several potentially modifiable risk factors associated with a wide variety of outcomes, especially cardiometabolic ones.
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Diagram of relationships between obesity, its risk factors, and potential consequences. Derived from Adams et al.
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These findings suggest that successful strategies to lower weight have the potential to reduce deaths and hospitalizations for several outcomes including those from another pandemic. 4 Reducing overweight and obesity will not be easy especially with obesity rates in the US continuing to increase. 12 But as recently as 1990, the US prevalence rate for overweight was 44.5% and obesity was 11.5%. 13 While the risk factors of diet and exercise are inherently broad and ill-defined, the BRFSS surveys include measures which should be easy to define and monitor. That diet measure is eating fruits and vegetables a combined < 5 or ≥ 5 times a day, and the exercise measures are living a sedentary lifestyle (no/yes for engaging in leisure time physical activity) and meeting (or not) the recommendations for participating in moderate physical activity ≥150 minutes a week or vigorous activity ≥75 minutes a week. Walking is a common example of moderate exercise. Results from the 2019 BRFSS 9 indicate that among the only 8.2% of adults eating fruits and vegetables ≥ 5X/day and meeting the exercise recommendation, 24.7% were obese compared with 36.8% of adults doing neither. While this rate does not achieve the threshold value of 15%, it represents a 33% reduction in obesity rates from the 47% of all adults doing neither. The states in which these adults resided had significantly lower deaths/million compared with states containing adults who reported both risk factors (1776 (1766-1785) vs 1804 (1801-1808) respectively). Corresponding reductions in rates of hypertension, heart disease, and diabetes for those reporting eating fruits and vegetables ≥5X/day and meeting physical activity recommendations were 24%, 35%, and 45%, respectively.
Consistent with the above findings, the WOF found that countries where populations were less physically active and consumed higher levels of animal fats, vegetable oils, and sugars were also more likely to have higher death rates from COVID-19. 4 The strongest association with increased death rates was shown for consumption of sugar-sweetened beverages. These results suggest additional changes that may be needed to further lower overweight and obesity rates beyond any reduction achieved with the 2 simple changes above.
In late 2020, Harvard scientists estimated the cost of COVID-19, assuming it would be substantially contained by the fall of 2021 with total deaths at 625 000. 14 Their total estimated cost was $16 trillion, 14 about half which was estimated due to premature deaths and long term physical and mental health effects and half to lost income from the economic shutdowns. These total costs amount to 90% of annual GDP and nearly $200,000 for a family of 4. With 2 very simple behavior changes - eating fruits and vegetables ≥5 times a day and walking (or the equivalent) 22 minutes each day - having the potential to reduce overweight and obesity and thus save lives, this seems like a strategy worth encouraging. Even if overweight is not lowered below the 50% threshold, 4 US data noted above8,9 indicate significant number of deaths could be prevented and it would be a start. Other factors that have been found to be associated with COVID death rates such as population density, the age of the population, GDP, ethnic makeup, and how the pandemic was handled 7 would likely be no easier to change than obesity and overweight. Although COVID-19 deaths continue at the present time, it is more realistic to consider any improvements from behavior change in the longer term, such as the next pandemic or deaths prevented due to diabetes, heart disease or hypertension. As difficult as it might be to change behaviors to significantly lower obesity and overweight rates, based on COVID impacts on health care, the economy, and life in general in the past 18 months and the estimated $16 trillion cost 14 the alternative is frightening to contemplate. Experience with COVID-19 shows that even with safe and effective vaccines, deaths continue.