We first estimated the marginal effect of obesity (in dollars), by BMI category, on overall healthcare spending (Table 1).
Table 1
Increase in Adult Per Capita Total Spending Attributable to Obesity in 2016 and 2006
Year | 2016 | | 2006 | |
BMI class | Mean spending difference compared to normal weight ($) | Proportion of population (weighted) (%) | Mean spending difference compared to normal weight ($) | Proportion of population (weighted) (%) |
Overweight | 367.11 [251.966] | 33.8 | 321.39* [189.187] | 34.6 |
Obese 1 | 1,028.65 *** [301.020] | 18.3 | 1,482.45*** [238.620] | 17.1 |
Obese 2 | 1,803.94 *** [412.280] | 8.0 | 2,165.40*** [348.764] | 6.3 |
Obese 3 | 2,718.67 *** [508.660] | 5.0 | 3,002.72*** [434.515] | 3.8 |
*p < 0.10 ** p < 0.05 ***p < 0.01
Marginal effects, standard errors between []
This marginal effect represents the mean association of spending with obesity, controlling for other factors. The largest difference in spending was for the Obese 3 class; individuals who are Obese 3 spent an average of $2,719 more per person per year in 2016 than those in a normal weight class. This is significantly higher than those in Obese 2, who spent an average of $1,804 more per person per year, and Obese 1, where mean spending was $1,029 per person per year. The increase in healthcare spending in Class 3 is problematic because the proportion of individuals in Class 3 has increased by 31.5% between 2006 and 2016 (from 3.8–5%). Surprisingly, the marginal effect was smaller in 2016 than 2006 for all obesity classes, after adjusting for inflation. The largest decline was for Obese 3, which declined from $3,003 in 2006 to $2,719 in 2016. This same trend was found for Obese 2, which went from $2,165 to $1,804 and Obese 1, which went from $1,482 to $1,029. Individuals in the overweight category were marginally significantly different (p < 0.1) from the reference group only for 2006, although the estimated coefficient for 2016 was similar to that for the earlier year. This time trend varies across payers (Table 2).
Table 2
Increase in Adult Per Capita Total Spending Attributable to Obesity in 2016 and 2006, By Payer
Insurance category | BMI category | Mean spending difference compared to normal weight ($) 2016 | Mean spending difference compared to normal weight ($) 2006 |
Medicare | Overweight | 700.12 [615.527] | -396.71 [645.569] |
| Obese 1 | 1,759.05*** [718.867] | 1,587.90** [803.166] |
| Obese 2 | 2,881.70*** [1,018.698] | 2,189.19** [1,140.802] |
| Obese 3 | 3,774.82*** [1,213.880] | 6,615.03*** [1,540.392] |
Medicaid | Overweight | 774.95 [755.025] | 306.68 [766.943] |
| Obese 1 | 662.26 [847.869] | 1,121.38 [871.873] |
| Obese 2 | 1,541.40 [1,105.689] | 2,621.23** [1,163.954] |
| Obese 3 | 2,953.68 *** [1,199.789] | 4,324.89*** [1,184.332] |
Private | Overweight | 189.26 [304.958] | 486.80 ** [249.337] |
| Obese 1 | 899.426 *** [369.729] | 1,633.36 *** [315.903] |
| Obese 2 | 1,634.05 *** [506.560] | 2,461,27 *** [466.720] |
| Obese 3 | 2,614.93 *** [651.227] | 2,787.39 *** [599.565] |
*p < 0.10 ** p < 0.05 ***p < 0.01 |
Marginal effects, standard errors between []
For Medicare, the costs for Obese 3 declined markedly from 2006 to 2016 ($6,615 to $3,775), while increasing for Obese 2 ($2,189 to $2,882) and Obese 1 ($1,588 to $1,759). Medicaid exhibited a similar trend for Obese 3, with a large decrease in the marginal cost ($4,325 to $2,954). Medicaid also showed decreases for Obese 2 ($2,621 to $1,541) and Obese 1 ($1,121 to $662), but the 2016 Obese 2 coefficient and both Obese 1 coefficients were statistically insignificant. For private insurance, spending went down for all three BMI classes, with the largest decrease for Obese 2 ($2,461 to $1,634).
Being overweight had no effect on spending overall. Although 33% of the population was overweight in 2016, the marginal effect overall (Table 1) and by payer (Table 2) was insignificantly different from zero for all models except private insurance in 2006.
The reason for these trends is suggested by Table 3. Inpatient spending for Obese 3 declined 35% from $1,110 to $727 from 2006 to 2016 and inpatient spending for Obese 2 declined 29% from $679 to $483. Inpatient spending for Obese 1 increased between 2006 and 2016 from $241 to $343. In contrast, non-inpatient spending increased for BMI classes 3 and 2, with an increase for Obesity 3 from $714 in 2006 to $869 in 2016, and an increase for Obese 2 from $592 to $751.
Meanwhile, there was a small decrease for Obese 1 in non-inpatient spending. Prescription drug spending was relatively flat for Obese 3 and Obese 2, but declined from $643 to $379 for Obese 1.
Table 3 suggests a shift in spending for obesity. For Obese 3, the most expensive spending category in 2006 was inpatient spending ($1,110), followed by prescription drugs ($1,031) and non-inpatient spending ($714). In contrast, the top expense in 2016 was for prescription drugs ($1,046), with inpatient spending third ($727). Obese 2 showed the same general pattern: a very slight decline in drug spending, an increase in non-inpatient spending and a decrease in inpatient spending.
Table 3
Increase in Adult Per Capita Total Spending Attributable to Obesity in 2016 and 2006, By Service Line
Type of Service | Obesity category | Mean spending difference compared to normal weight ($) 2016 | Mean spending difference compared to normal weight ($) 2006 |
Inpatient | Overweight | 239.01 [168.218] | 9.81 [108.656] |
| Obese 1 | 353.49 ** [172.540] | 241.42 * [141.323] |
| Obese 2 | 483.46 ** [235.758] | 679.46 *** [177.842] |
| Obese 3 | 727.23 *** [251.747] | 1,110.10 *** [209.555] |
Non-inpatient | Overweight | 220.57 ** [103.852] | 7.54 [69.645] |
| Obese 1 | 396.07 *** [124.030] | 435.29 *** [87.427] |
| Obese 2 | 751.34 *** [169.683] | 592.21 *** [126.827] |
| Obese 3 | 868.66 *** [208.378] | 714.17 *** [156.638] |
Rx | Overweight | -27.82 [118.381] | 181.226 *** [51.697] |
| Obese 1 | 379.05 *** [125.496] | 643.61 *** [150.279] |
| Obese 2 | 632.33 *** [160.973] | 671.49 *** [72.626] |
| Obese 3 | 1,045.79 *** [145.211] | 1,031.44 *** [86.354] |
*p < 0.10 ** p < 0.05 ***p < 0.01 |
Marginal effects, standard errors between []
Overall, changes in the attributable fraction of healthcare spending varied depending on the service line and BMI category (Table 4). For inpatient care, the attributable fraction declined for Obese 2 (3.2–1.9%) and Obese 3 (3.9–2.5%), but increased for Obese 1 (2.4–3.5%). Non-inpatient and prescription drug spending had exactly the opposite pattern, with the attributable fraction decreasing for Obese 1 (5.6–4.0%) while increasing for Obese 2 (3.0–3.5%) and Obese 3 (2.2–2.5%). Finally, the attributable fraction for prescription drug spending decreased for both Obese 1 (7.6–5.3%) and Obese 2 (4.3–4.1%) and increased slightly for Obese 3
(4.2–4.3%).
Table 4
Aggregate total medical spending attributable to levels of obesity, by Service Line
| Service Line | Overweight | Obese 1 | Obese 2 | Obese 3 |
2016 | Inpatient | 3.9 (3.17) 12.4 | 3.5 (2.08) 10.9 | 1.9 (1.20) 5.9 | 2.5 (0.88) 7.8 |
| Non-Inpatient | 3.9 (2.05) 16.7 | 4.0 (1.42) 17.4 | 3.5 (1.01) 15.0 | 2.5 (0.62) 10.5 |
| Rx | -1.2 (2.05) -4.2 | 5.3 (1.56) 18.0 | 4.1 (0.99) 14.1 | 4.3 (0.58) 14.9 |
2006 | Inpatient | 1.8 (3.33) 5.1 | 2.4 (1.68) 6.8 | 3.2 (1.00) 9.1 | 3.9 (1.09) 11.2 |
| Non-inpatient | 0.2 (1.70) 0.5 | 5.6 (1.35) 16.9 | 3.0 (0.84) 9.2 | 2.2 (0.48) 6.8 |
| Rx | 5.1 (1.19) 12.2 | 7.6 (1.28) 18.3 | 4.3 (0.43) 10.2 | 4.2 (0.44) 10.0 |
Attributable fraction (%) and Total spending ($ million). Standard error in parentheses.
Actual spending increased for prescription drugs and non-inpatient care for Obese 3, with a nearly $5B increase in prescription drug spending alone. Spending in Obese 2 had the largest overall increase, with an increase of nearly $4B in prescription drugs ($10.2B to $14.1B) and $6B in non-inpatient care. Spending for Obese 1 was largely flat for prescription drugs and non- inpatient care. Inpatient spending declined for Obesity Class 2 ($3.2B) and Obesity Class 3 ($3.4B), but increased for Obese Class 1 ($4.1B).
The effect by payer varied (Table 5). Medicare experienced an increase in attributable fraction for Obese 1 (from 3.1% in 2006 to 3.6% in 2016) and Obese 2 (1.8–2.4%) and a decline for Obese 3 (from 4.0–2.3%). Medicaid also experienced an increase in attributable fraction for Obese 1 (from 2.7–3.5%), while Private Insurance saw a decrease for that same class (from 7.0–3.6%). Both Medicaid and Private Insurance saw deceases in the attributable fraction for Obese 2 (3.8–2.2% and 4.2–2.9%, respectively).
Table 5
Aggregate total medical spending attributable to levels of obesity, by Payer
| Insurance Category | Overweight | Obese 1 | Obese 2 | Obese 3 | TOTAL ($ billion) |
2016 | Medicare | 2.3 (2.58) 12.0 | 3.6 (1.84) 18.8 | 2.4 (1.16) 12,5 | 2.3 (0.13) 12.3 | |
| Medicaid | 3.5 (4.31) 6.6 | 1.9 (2.67) 3.5 | 2.2 (1.72) 4.2 | 4.3 (1.50) 8.0 | |
| Private | 1.3 (2.38) 9.4 | 3.6 (1.33) 25.9 | 2.9 (0.92) 21.0 | 2.8 (0.74) 19.9 | |
| | | 48.2 | 37.7 | 40.2 | 126.1 |
2006 | Medicare | -1.4 (2.32) -5.1 | 3.1 (1.42) 11.1 | 1.8 (0.79) 6.2 | 4.0 (1.30) 14.1 | |
| Medicaid | 1.1 (2.85) 1.1 | 2.7 (2.37) 2.7 | 3.8 (2.47) 3.9 | 6.8 (2.63) 7.0 | |
| Private | 3.7 (1.78) 21.0 | 7.0 (1.70) 40.1 | 4.2 (0.86) 24.2 | 2.6 (0.53) 15.0 | |
| | | 53.9 | 34.3 | 36.1 | 124.3 |
Attributable fraction (%) and Total spending ($ billion). Standard error in parentheses.
Row totals exclude Overweight, to calculate obesity total spending.
The pattern for Obese 3 was similar, with declines for Medicaid (6.8–4.3%) and Private Insurance largely unchanged (2.6–2.8%). Overall spending for Obese 1 decreased from $53.9 billion to $48.2 billion, while it increased for Obese 2 from $34.3B to $37.7B and for Obese 3 from $36.1B to $40.2B. Total spending increased from $124.3B to 126.1B, even though spending in Obesity 1, the largest group, declined. The largest increase is in Obese 3 (from 36.1B to 40.2B), an increase that nearly matched the decrease in spending Obesity 1, despite the Obese 1 group being more than three times as large.