Size at Birth, Fat-Free Mass and Resting Metabolic Rate in Adult Life

Abstract

Resting metabolic rate is an important predictor of obesity and is closely related to fat-free mass. There is evidence that fat-free mass may be partly determined during critical periods of growth before and after birth. The objective of this study was to examine the relationship between size at birth, childhood growth and fat-free mass and resting metabolic rate in adult life. 318 men and women with detailed records of body size at birth and growth during school years participated in the study. Fat-free mass correlated positively with birth weight among both sexes (r = 0.264, p < 0.001). Those having a higher birth weight had a higher fat-free mass at any adult BMI. Fat-free mass among men increased by 2.2 kg (95 % Cl 0.5 to 3.9; p = 0.01) for every kg increase in birth weight and by 1.5 kg (95 % Cl 1.3 to 1.7, p < 0.0001) for every kg/m(2) BMI in adult life. In women, fat-free mass increased by 2.7 kg (95 % Cl 1.6 - 3.9; p < 0.001) for every kg increase in birth weight and by 0.8 kg (95 % CI 0.7 to 1.0, p < 0.001) for every kg/m(2) of BMI in adult life. Height, weight and body mass index at each age from 7 to 15 years were also strongly, positively associated with fat-free mass. A negative correlation between birth weight and resting metabolic rate expressed per unit of fat-free mass (r = - 0.158; p < 0.001) was found. Fat-free mass may be determined during critical periods of muscle growth in utero and during childhood. The muscle tissue of people who had a lower birth weight is more metabolically active than those with a higher birth weight. This may protect them from the increased risk of obesity associated with low fat-free mass.

Tracking of overweight from early childhood to adolescence in cohorts born 1988 and 1994: overweight in a high birth weight population

“…It has been suggested that the association between birth weight and BMI in cohorts older than those studied in the present study could be related to more muscle mass developed at a critical period in foetal life close to week 30 in utero as well as during childhood. 23 That theory is supported by an association between birth weight and fatfree mass in adulthood at any adult BMI, 23 and an inverse relation between birth weight and adult truncal fat. 22 This indicates the weakness of BMI as a measure of body composition or body fatness.…”

“…21,22 The association is probably due to larger muscle mass developed in critical periods in foetal life and in childhood leading to higher birth weight and adult BMI in the cohorts from early in last century. 22,23 The prevalence of overweight and obesity has increased at all ages during the last decades. More knowledge is needed about the impact of size at birth on the growing generation's BMI.…”

Association between size at birth, truncal fat and obesity in adult life and its contribution to blood pressure and coronary heart disease; study in a high birth weight population

“…Foetal programming of lean body mass has been suggested in recent studies (Weyer et al, 2000;Eriksson et al, 2002;Singhal et al, 2003). It would have been desirable to include a measure of body composition at birth, such as arm circumference and skinfolds (Koletzko et al, 2002).…”

“…It would have been desirable to include a measure of body composition at birth, such as arm circumference and skinfolds (Koletzko et al, 2002). There is a critical period for muscle growth around 30 weeks in utero, and fat-free mass may be determined during critical periods of muscle growth in utero as well as during childhood (Eriksson et al, 2002). The mean BMI of women of childbearing age was 24.4 kg/m 2 in Iceland at the time of the study (Statistics Iceland, 1997).…”

Thrifty energy metabolism in catch-up growth trajectories to insulin and leptin resistance

“…These differences in body composition, associated with impaired glucose metabolism, may persist into adulthood, as suggested by studies from Finland 35 and from England using DEXA scan 36 , indicating that for the same BMI as age-matched controls, healthy elderly individuals born SGA have 3-5 kg less lean tissue mass, more fat mass, and a more central fat distribution. Similarly, studies from Denmark in cohorts of healthy young men born SGA indicate that they have slightly less lean tissue mass and slightly more body fat, but clearly higher abdominal fat mass 37 than age-matched controls of similar BMI, or that they showed reduced forearm glucose uptake 38 and reduced muscle expression of key proteins involved in insulin signalling and glucose transport.…”