Birth-weight and resting metabolic rate in adulthood — sex-specific differences

Figures & data

Table I. Clinical characteristics for 408 men and 488 women participating in the study.

	Male			Female
Characteristics	Mean	SD	Range	Mean	SD	Range
Birth characteristics
Birth-weight (g)	3472	509	1850–5050	3347	478	1800–5400
Ponderal index (kg/m^3)	26.6	2.2	16.8–35.1	26.7	2.3	20.4–34.3
Gestational age (days)	279.7	11.2	253.0–309.0	280.7	10.8	251.0–309.0
Adult life
Age (years)	61.5	2.7	57.2–68.6	61.6	3.1	56.7–69.8
Height (cm)	176.4	6.1	157.0–197.0	163.2	5.6	148.0–180.0
Weight (kg)	85.0	13.4	49.0–142.1	73.7	14.4	40.1–132.9
Body mass index (kg/m^2)	27.3	4.0	19.6–45.9	27.7	5.2	14.7–49.9
Systolic blood pressure (mmHg)	145.9	17.9	99.5–209.5	144.0	21.1	99.0–222.5
Diastolic blood pressure (mmHg)	90.5	10.3	62.0–130.0	87.0	9.9	62.5–121.0
Fat percentage (%)	23.4	5.9	9.4–46.4	33.9	7.1	12.3–55.6
Fat-free mass (kg)	64.5	7.8	42.9–96.3	47.9	6.0	33.4–68.4
Fat mass (kg)	20.4	8.0	5.7–65.9	25.8	10.0	4.9–68.6
Resting metabolic rate (kcal/24 h)	1708	203	1130–2480	1380	143	1060–1980
Respiratory quotient	0.83	0.04	0.70–0.94	0.82	0.04	0.71–0.96

Figure 1. (A) The association between age-adjusted resting metabolic rate and birth-weight for men. (B) The association between age-adjusted resting metabolic rate and birth-weight for women.

Figure 2. (A) The association between RMR adjusted for fat-free mass and age and birth-weight for men. (B) The association between RMR adjusted for fat-free mass and age and birth-weight for women.

Table II. Estimated regression effects of birth-weight (kg) on RMR (kcal/24 h) adjusted for age and FM, FFM, or both. A smaller Akaike's information criterion (AIC) corresponds to a better model fit.

	Linear effect size* with 95% CI	Quadratic effect size* with 95% CI	AIC
Linear models
Men
adjustment for age	98.0 (61.0, 135.0)	–	5460.2
adjustment for age and FFM	2.6 (−15.6, 20.7)	–	4847.6
adjustment for age and FM	59.6 (36.7, 82.4)	–	5060.3
adjustment for age, FFM, and FM	2.5 (−3.6, 8.6)	–	3959.7
Women
adjustment for age	48.9 (22.8, 74.9)	–	6213.6
adjustment for age and FFM	−20.0 (−33.9, −6.0)	–	5570.9
adjustment for age and FM	34.6 (24.7, 44.4)	–	5260.2
adjustment for age, FFM, and FM	2.2 (−0.9, 5.3)	–	4097.5
Quadratic models
Men
adjustment for age	−660.9 (−977.1, 344.7)	110.3 (64.6, 156.0)	5440.2
adjustment for age and FFM	−210.3 (−364.0, 56.7)	31.1 (8.8, 53.5)	4842.1
adjustment for age and FM	−239.9 (−439.2, 40.6)	43.6 (14.8, 72.5)	5053.5
adjustment for age, FFM, and FM	−51.9 (−104.1, 0.3)	8.0 (0.4, 15.5)	3957.4
Women
adjustment for age	−100.3 (−335.8, 135.3)	22.0 (−12.5, 56.5)	6214.1
adjustment for age and FFM	−67.0 (−188.9, 54.9)	6.9 (−10.9, 24.8)	5572.3
adjustment for age and FM	−3.4 (−92.1, 85.3)	5.6 (−7.4, 18.6)	5261.5
adjustment for age, FFM, and FM	−15.3 (−42.2, 11.6)	2.6 (−1.4, 6.5)	4097.8

* = Effect sizes represent change in RMR/kg birth-weight only in the linear models. For a visual representation of the quadratic effects, please see Figures 1A and 2A.