MET-values of standardised activities in relation to body fat: studies in pregnant and non-pregnant women

Sedentarism and Chronic Health Problems

Increased mechanization and technological advances have simplified our lives on the one hand and increased sedentary behaviors on the other hand, paving the way for emerging global health concerns, i.e., sedentarism, which could be the leading cause of all major chronic health problems worldwide. Sedentarism is a habitual behavior of choosing and indulging in low-energy expenditure activities (≤1.5 metabolic equivalents), such as chairtype (sitting, studying, traveling) or screen-type activities (TV, computers, mobile). With technological advancements, there is a significant transition in the lifestyles of people from being active (walking) to being more deskbound (sitting). Prolonged sitting can have unintended consequences for health with sitting time >7 h/d, leading to a 5% increase in all-cause mortality with each additional hour spent sitting (i.e., +7 h/d), while considering physical activity levels. This review will highlight how sedentarism is emerging as a major risk factor for the rising incidence of non-communicable diseases, especially among young adults and adults. Chronic diseases, such as obesity, diabetes, coronary heart disease, and cancer, are the leading causes of death worldwide. Hence, there is an urgent need for collective action to mitigate the burgeoning public health crisis posed by sedentarism in the 21st century. This paper intends to set in motion a call for all policymakers and public health professionals placed nationally or internationally to reach a consensus on ending sedentarism and provide viable resolutions for effective management of excessive sedentary behaviors and healthy adoption and maintenance of active lifestyles among individuals of all age groups.

Body composition helps: Differences in energy expenditure between pregnant and nonpregnant females

OBJECTIVES

Human pregnancy is associated with important physiological changes that usually increase energetic requirements. However, great variability exists in the costs and mechanisms required to bear pregnancy. Since body mass (BM) and composition are modified during gestation, it is of great interest to compare the influence of BM on energy expenditure (EE) in pregnant and nonpregnant females.

METHODS

BM, body composition, and EE of 77 volunteers (35 pregnant and 42 nonpregnant females) were measured. The pregnant volunteers completed two measurement rounds at 28 and 32 gestation weeks. Differences on the measured parameters were sought, and comparison of regression lines was computed to test how BM affected the EE of the volunteers.

RESULTS

BM and body composition parameters are significantly higher in pregnant females, but EE is not statistically different. Pregnant females have a larger percentage of fat mass, but lower percentage of fat-free mass (FFM). The EE per kg of FFM is similar in both groups. Comparison of regression lines shows that pregnancy does not change the relationship between BM and EE, but for similar BM pregnant females expend less energy than nonpregnant females.

CONCLUSIONS

We propose that their larger percentage of passive body tissues is the reason why pregnant females expend less energy than nonpregnant females of similar BM, without changing the scaling of EE on BM. Thus, pregnancy could not be as energetically constraining as usually assumed, with important consequences for human reproductive ecology.