Table 1.
Baseline Characteristics of the Study Cohort
| Total (n = 108) | Spendthrift (n = 54) | Thrifty (n = 54) | P value | |
|---|---|---|---|---|
| Male, n (%) | 83 (76.9) | 41 (75.9) | 42 (77.8) | 0.82 |
| Ethnicity, n (%) | 0.5 | |||
| African-American | 20 (18.5) | 11 (20.4) | 9 (16.7) | |
| Caucasian | 37 (34.3) | 14 (25.9) | 23 (42.6) | |
| Native American | 36 (33.3) | 18 (33.3) | 18 (33.3) | |
| Hispanic | 15 (13.9) | 11 (20.4) | 4 (7.4) | |
| Age, years | 36.6 ± 10.4 (18, 55.4) | 36.4 ± 10.2 (18, 55.4) | 36.8 ± 10.6 (18.3, 55) | 0.87 |
| Height, cm | 171.8 ± 8.1 (150.0, 196.4) | 172.0 ± 8.0 (156.8, 196.4) | 171.7 ± 8.3 (150.0, 185.0) | 0.89 |
| Weight-maintaining diet intake, kcal/day | 2713 ± 211 (2196, 3295) | 2731 ± 225 (2312, 3295) | 2695 ± 198 (2196, 3106) | 0.39 |
| Body composition measures | ||||
| Body weight, kg | 83.4 ± 18.7 (47.5, 139.2) | 85.5 ± 20.8 (56, 139.2) | 81.4 ± 16.2 (47.5, 119.3) | 0.25 |
| BMI, kg/m2 | 28.3 ± 6.6 (17.8, 49.9) | 29.1 ± 7.6 (20.6, 49.9) | 27.6 ± 5.4 (17.8, 42.9) | 0.24 |
| Body fat, % | 26.8 ± 9.1 (7.6, 46.1) | 27.1 ± 10 (7.9, 45.8) | 26.5 ± 8.1 (7.6, 46.1) | 0.72 |
| FM, kg | 23.3 ± 11.7 (5.4, 56.3) | 24.4 ± 13.4 (5.4, 56.3) | 22.1 ± 9.8 (6.4, 50.7) | 0.31 |
| FFM, kg | 60.1 ± 11 (35.5, 90) | 61.2 ± 11.4 (37.8, 90) | 59.1 ± 10.5 (35.5, 80.6) | 0.32 |
| Measurements of glucose tolerance and insulin sensitivity | ||||
| Fasting glucose, mg/dL | 91.8 ± 6.2 (77.5, 113) | 92.3 ± 5.6 (80, 113) | 91.4 ± 6.7 (77.5, 109.5) | 0.46 |
| Fasting insulin, μIU/mL | 10.1 ± 7.7 (2, 46.5); 7.3, 5.0–13.0* | 10.3 ± 7.6 (2, 32.4); 7.2, 5.3–13.5* | 9.9 ± 8 (2, 46.5); 7.5, 5.0– 13.0* | 0.71 |
| 2-h glucose during OGTT, mg/dL | 110.2 ± 26.2 (50, 185) | 113 ± 26.6 (50, 185) | 107.2 ± 25.7 (65, 183) | 0.26 |
| 2-h insulin during OGTT, μIU/mL | 68.5 ± 82 (3, 523); 45.0, 27.0–73.4* | 75.2 ± 82.8 (3, 509.8); 51.2, 30.0–88.0* | 61.7 ± 81.5 (4, 523); 43.0, 20.0–69.0* | 0.17 |
| Energy expenditure measures during energy balance (ENBAL) | ||||
| RQ ratio | 0.86 ± 0.04 (0.76, 1.00) | 0.87 ± 0.03 (0.80, 0.94) | 0.86 ± 0.04 (0.76, 1.00) | 0.34 |
| 24EE, kcal/day | 2074 ± 357 (1383, 3188) | 2053 ± 393 (1502, 3188) | 2096 ± 319 (1383, 2830) | 0.53 |
| Adjusted 24EE, kcal/daya | 2074 ± 137 (1707, 2461) | 2012 ± 141 (1707, 2461) | 2136 ± 102 (1918, 2438) | <0.0001 |
| ∆ adjusted 24EE during fastinga | –172 ± 93 (–470, 122) | –98 ± 57 (–162, 122) | –245 ± 58 (–470, –162) | <0.0001 |
| 24EE/FFM, kcal/day/kg | 34.7 ± 3.5 (25.5, 42.5) | 33.7 ± 3.7 (25.5, 41.7) | 35.7 ± 3.0 (28.6, 42.5) | 0.003 |
| SLEEP, kcal/day | 1637 ± 279 (1073, 2306) | 1619 ± 292 (1193, 2306) | 1655 ± 268 (1073, 2303) | 0.50 |
| Adjusted SLEEP, kcal/daya | 1637 ± 120 (1384, 2066) | 1594 ± 101 (1384, 1799) | 1681 ± 122 (1386. 2066) | <0.0001 |
| ∆ adjusted SLEEP during fastinga | –15 ± 111 (–403, 262) | +33 ± 89 (-147, 262) | −63 ± 111 (-403, 179) | <0.0001 |
| EE0, kcal/15h | 1375 ± 237 (941, 2098) | 1364 ± 263 (965, 2098) | 1385 ± 210 (941, 1955) | 0.65 |
| Adjusted EE0, kcal/15ha | 1375 ± 91 (1133, 1617) | 1337 ± 95 (1133, 1617) | 1413 ± 68 (1256, 1536) | <0.0001 |
| ∆ adjusted EE0during fastinga | –170 ± 75 (–390, 1) | –117 ± 48 (–204, 1) | –223 ± 58 (–390, –89) | <0.0001 |
| AFT, kcal/15h | 352 ± 109 (145, 695) | 353 ± 114 (172, 657) | 351 ± 105 (145, 695) | 0.95 |
| Adjusted AFT, kcal/15ha | 352 ± 84 (195, 601) | 340 ± 79 (217, 601) | 363 ± 87 (195, 539) | 0.15 |
| 24h Energy intake, kcal/day | 2115 ± 347 (1461, 2956) | 2102 ± 380 (1461, 2956) | 2127 ± 313 (1508, 2829) | 0.72 |
| SPA, % of time | 5.8 ± 3.2 (0.7, 16.4) | 6 ± 3.6 (0.7, 16.4) | 5.6 ± 2.8 (0.7, 15.5) | 0.58 |
| Night time SPA, % of time | 1.8 ± 1.6 (0.0, 9.7) | 1.6 ± 1.6 (0.0, 9.7) | 2.0 ± 1.9 (0.0, 8.1) | 0.17 |
| PAL, 24EE/SLEEP, ratio | 1.3 ± 0.1 (1.1, 1.5) | 1.3 ± 0.1 (1.1, 1.5) | 1.3 ± 0.1 (1.1, 1.4) | 0.85 |
| Energy expenditure measures during 24h fasting | ||||
| RQ ratio | 0.79 ± 0.03 (0.71, 0.90) | 0.79 ± 0.03 (0.73, 0.86) | 0.79 ± 0.03 (0.71, 0.90) | 0.96 |
| 24EE, kcal/day | 1903 ± 311 (1254, 2811) | 1935 ± 344 (1365, 2811) | 1871 ± 273 (1254, 2486) | 0.29 |
| Adjusted 24EE, kcal/daya | 1903 ± 123 (1633, 2315) | 1914 ± 193 (1633, 2315) | 1892 ± 105 (1654, 2184) | 0.35 |
| 24EE/FFM, kcal/day/kg | 31.9 ± 3.0 (24.9, 40.2) | 31.8 ± 3.4 (24.9, 40.2) | 31.9 ± 2.7 (26.5, 40.2) | 0.87 |
| SLEEP (kcal/day) | 1622 ± 258 (1110, 2382) | 1644 ± 266 (1129, 2382) | 1601 ± 250 (1110, 2373) | 0.39 |
| Adjusted SLEEP, kcal/daya | 1622 ± 121 (1364, 2087) | 1627 ± 122 (1370, 1955) | 1618 ± 122 (1364, 2087) | 0.69 |
| EE0, kcal/15h | 1205 ± 200 (809, 1787) | 1234 ± 227 (854, 1787) | 1176 ± 165 (809, 1602) | 0.14 |
| Adjusted EE0, kcal/15ha | 1205 ± 85 (1012, 1426) | 1219 ± 95 (1012, 1426) | 1191 ± 70 (1026, 1359) | 0.08 |
| ANFT, kcal/15h | 194 ± 95 (0, 493) | 210 ± 102 (0, 493) | 177 ± 85 (0, 353) | 0.07 |
| Adjusted ANFT, kcal/15ha | 194 ± 82 (-77, 395) | 206 ± 77 (41, 395) | 182 ± 86 (-77, 346) | 0.12 |
| SPA, % of time | 5.3 ± 3.1 (0.4, 18.3) | 5.2 ± 3.2 (0.8, 18.3) | 5.4 ± 3.1 (0.4, 12.7) | 0.75 |
| Night time SPA, % of time | 1.8 ± 1.6 (0.0, 7.5) | 1.8 ± 1.6 (0.0, 7.0) | 1.8 ± 1.5 (0.0, 7.5) | 0.93 |
| PAL, 24EE/SLEEP, ratio | 1.2 ± 0.1 (1.0, 1.4) | 1.2 ± 0.1 (1.0, 1.3) | 1.2 ± 0.1 (1.0, 1.4) | 0.77 |
Values are presented as mean ± SD for continuous variables or number (frequency) for categorical variables with minimum and maximum in parentheses. Skewed values are also expressed as medians with interquartile ranges (*). Classification of subjects into spendthrift or thrifty metabolic group was based on the median value of change (∆) in adjusted 24EE from energy balance during fasting (−162 kcal/day), such that thrifty subjects were those with a greater-than-median decrease in 24EE.
Significance between thrifty and spendthrift metabolic groups was determined by Student’s unpaired t-test. Significant differences are highlighted in bold.
aAdjusted energy expenditure values were calculated by adding the average value calculated in the whole cohort to the residual values obtained from linear regression models with covariates age, sex, ethnicity, FM, FFM, spontaneous physical activity, ambient temperature, and calorimeter room.
Abbreviations: 24EE, 24h energy expenditure; AFT, awake-fed thermogenesis; ANFT, awake-nonfed thermogenesis; BMI, body mass index; EE0, nonactivity energy expenditure; FM, fat mass; FFM, fat-free mass; OGTT, oral glucose tolerance test; PAL, physical activity level; RQ, respiratory quotient; SLEEP, sleeping energy expenditure; SPA, spontaneous physical activity.