This article - featuring exclusive RGA research - dives into the mortality impacts of exercise on an obese population to better understand the effects of different levels of exercise and intensity across various age groups. It also compares the mortality experience of the obese population to the non-obese population.
Amid today’s GLP-1 drug revolution, a new RGA analysis of US health data reveals that good old-fashioned exercise – in nearly any amount – provides a significant reduction in mortality for obese individuals.
These findings are especially relevant for insurers offering or seeking to implement wellness programs geared toward increasing activity levels and promoting healthy lifestyles.
Obesity rates have been steadily increasing in the US for many years. From 2017 to early 2020, approximately 41.9% of US adults 20 and over were considered obese – up from 30.5% in 1999-2000. At the same time, the prevalence of severe obesity – defined as a BMI of 40 or higher – also increased from 4.7% to 9.2% [1].
These trends in increasing obesity carry mortality implications. Obesity is linked to high blood pressure, Type 2 diabetes, many types of cancer, and premature death [2]. Obesity has been classified as the #4 leading risk factor in the US, falling just behind smoking [3].
These obesity trends and the corresponding mortality implications present a cause for concern, especially if they persist into the future.
RGA analyzed data from the National Health Interview Survey (NHIS), a US-based survey dataset, with mortality linkage from the period 1987-2015 [4] and developed multivariate survival models to assess the impact of lifestyle behaviors on mortality within the US population, controlling for age, sex, smoking, disease history, health status, and income. These were adjusted based on income and insurable interest to make findings more applicable to an insured population. RGA researchers first categorized the NHIS dataset into obese and non-obese populations, where the obese population was defined as individuals with a BMI of 30 or more, and the non-obese population consisted of individuals with a known BMI less than 30. All-cause mortality experience was broken out by self-reported activity level.
In Figure 2, it is apparent that any level of exercise provides mortality benefits. These benefits appear to be slightly lower for the obese population, but there is still a benefit, nonetheless. More exercise generally improves all-cause mortality risk for both populations, demonstrating that incorporating exercise into daily life is shown to lower mortality regardless of BMI.
Source: RGA analysis of NHIS data, 1987-2015; multivariate model adjusts for age, sex, smoking, disease history, health status and income.
These two populations were then split into activity level groups based on the World Health Organization’s (WHO) recommended ranges of exercise. These recommended ranges not only accounted for the total time of exercise but also were adjusted for intensity of exercise, defined as one of the following:
Results in Figure 3 align well with the results in Figure 2, further emphasizing that increased exercise is generally beneficial for the all-cause mortality of both the obese and non-obese populations, albeit slightly lower effects for the obese population. Both populations may see additional benefit by exercising above the recommended ranges prescribed by WHO.
These results also align well with a study published by the American Heart Association, which indicated that reduced mortality was seen for individuals who exercised two to four times the recommended range[6].
To better understand the impact of exercise intensity, the obese population was further split into different activity groups. Individuals were grouped based on whether they met only the moderate or the vigorous recommendation of exercise, if they met both recommendations, if they exercise but did not meet either recommendation2, or if they chose not to exercise at all.
Figure 4 shows that individuals who met the vigorous recommendation of exercise had the lowest all-cause mortality risk. Those who met both the recommended vigorous and moderate amounts of exercise saw benefits similar to those who met only the vigorous recommendation. People who met only the moderate recommendation had slightly lower mortality benefits. This particular analysis indicates that any exercise is beneficial for the obese population, but higher intensity exercise can provide added mortality benefit.
Source: RGA analysis of NHIS data, 1987-2015; multivariate model adjusts for age, sex, smoking, disease history, health status and income.
Lastly, the analysis assessed mortality differences by age group: 20-49, 50-64, and 65+. Within these age groups, the individuals were split into activity levels that identified whether they met (or exceeded) the WHO recommended range of exercise. Figure 5 illustrates that exercise is generally beneficial in any age group, particularly if individuals meet or exceed the recommended range of exercise.
Individuals age 65+ present larger mortality benefits from exercise, seeing an average reduction in all-cause mortality of over 27% when meeting the recommended range of exercise relative to those who can exercise but do not.
This compares to the average mortality reduction of approximately 17% for the individuals meeting the recommended level of exercise within the two younger age groups. The results emphasize the heightened importance of exercise for older-aged, obese individuals.
Source: RGA analysis of NHIS data, 1987-2015. Multivariate model adjusts for age, sex, smoking, disease history, health status and income.
Obesity is a contributor to death and disease, which is a concern for the general public and insurers alike. Recently, weight loss drugs have received a lot of hype and generated a lot of excitement. However, sustained use of these drugs may not be feasible to everyone aspiring to lose weight and improve health. Therefore, RGA sought to better understand the mortality impacts of exercise for the obese population to better inform insurers and their wellness programs.
Through this analysis, RGA found that exercise is indeed beneficial to the obese population. Higher intensity, vigorous exercise provided additional mortality benefits beyond moderate intensity exercise. While exercise is beneficial at all ages, the benefits increased with age indicating a higher importance within older populations.
Footnotes:
1 As noted by Our World in Data: “The estimated annual number of deaths attributed to each risk factor. Estimates come with wide uncertainties, especially for countries with poor vital registration. Data source: IHME, Global Burden of Disease (2024) – with minor processing by Our World in Data. Note: Risk factors are not mutually exclusive. The sum of deaths attributed to each risk factor can exceed the total number of deaths.” More details on specific risk factors and their definitions can be found on IHME’s Disease, injury, and risk factsheets at https://www.healthdata.org/research-analysis/diseases-injuries-risks/factsheets.
2 Individuals who meet neither individual requirement (moderate or vigorous) could still technically reach a combined requirement; however, this analysis focused on meeting at least one specific intensity requirement to better understand the impacts of the intensity of exercise.
[1] U.S. Centers for Disease Control and Prevention, "Adult Obesity Facts," 2024.
[2] U.S. Centers for Disease Control and Prevention, "Consequences of Obesity," 2022.
[3] IHME, "Global Burden of Disease," 2024.
[4] L. A. Blewett, J. A. Rivera Drew, M. L. King, C. K. Williams, D. Backman, A. Chen and S. Richards, "PUMS Health Surveys: National Health Interview Survey, Version 7.4 [dataset]," IPUMS, Minneapolis, MN, 2024.
[5] World Health Organization, "Physical activity," 2024.
[6] American Heart Association, "New study finds lowest risk of death was among adults who exercised 150-600 minutes/week," 2022.
