Association Between Blood Pressure and Resting Energy Expenditure Independent of Body Size

Abstract

Abstract-Obesity is an important risk factor for hypertension; however, the pathway through which it raises blood pressure (BP) is poorly understood. Body size is also the primary determinant of energy expenditure, and we therefore examined the joint relationship of energy expenditure and body size to blood pressure. Resting energy expenditure (REE) was measured using respiratory gas exchange in population-based samples of 997 Nigerians and 452 African Americans. In a third sample of 118 individuals, nonresting energy expenditure (ie, physical activity) was measured in addition to REE. The univariate correlation between REE and BP ranged from 0.10 to 0.22 in the 3 samples (PϽ0.001).In multivariate models, adiposity, whether defined by body mass, fat mass, or leptin, was no longer associated with BP, while REE remained highly significant (PϽ0.001). The REE-BP association also persisted after adjustment for physical activity measured with doubly labeled water. The odds ratio for hypertension among persons in the highest quartile versus the lowest quartile of REE, after adjustment for body size, was 1.7. This relationship was not the result of hypertension among the obese, because it did not vary across the range of BMI and was the same in lean Nigerians as in obese Americans. These data suggest that metabolic processes represented by REE may mediate the effect of body size on BP. The interrelationship of REE with sympathetic tone, transmembrane ion exchange, or other metabolic processes that determine energy costs at rest could provide physiological explanations for this observation. . Although height appears to have little or no influence on BP among humans, adiposity has been universally identified as a predictor of increased risk of hypertension. 1,2 Despite substantial efforts, the underlying physiological mechanisms linking excess body fat stores to BP are poorly understood. Obesity is a complex syndrome, representing the joint effect of metabolic alterations as well as lifestyle patterns that involve, among others, a high-calorie/highsodium intake and reduced physical activity. 3 Various regulatory hormones, including insulin and leptin, are increased among the obese, and abnormalities in the renin-angiotensin system have been described. 4 -6 At the same time, a wide range of other metabolic abnormalities, including rates of ion transport and resting sympathetic tone, have been reported in obese hypertensives compared with the non-obese, although these associations are inconsistent. 7 An important challenge faced by studies that attempt to isolate the role of individual components of body composition and energy metabolism is the need to account for their intercorrelation. Although it is often assumed that the size of body fat stores is a primary determinant of hypertension risk, lean body mass increases in parallel with total body weight and is highly correlated with fat mass. 8 In addition, in societies where virtually the entire population experiences some degree of overweight, it may be difficult to iden...

Discordant Secular Trends in Elevated Blood Pressure and Obesity in Children and Adolescents in a Rapidly Developing Country

“…44 We observed for a given level of BMI that BP was lower, which could be explained by changes in the distribution of body fat (abdominal versus subcutaneous) or in the proportion of fat versus lean mass. 45 This finding also suggests that obesity may be associated with a lower cardiovascular risk than previously. 11 The mechanisms at stake remain highly speculative, and studies are needed to provide further evidence.…”

Association of Lactate With Blood Pressure Before and After Rapid Weight Loss

“…In support of this notion, several teams have found an association between resting energy expenditure and hypertension. 33,34 Futhermore, as people gain weight, the capacity to meet increasing energy demand may decrease due to mitochondrial dysfunction. 3,7 In obese persons, mitochondrial size is smaller, 3 the expression of genes involved in oxidative phosphorylation is reduced, 7 and the activity of glycolytic enzymes is increased.…”

Blood pressure and body mass index in lean rural and semi-urban subjects in West Africa

“…In populations of African origin, however, the percentage of body fat, as measured by bio-electrical impedance or by measurement of the waist or hip circumference, has not been found to be a better predictor of BP than BMI [24]. More recently, the importance of resting energy expenditure (REE) -and therefore the role of the metabolically active fat-free body mass -has been studied in populations both in Africa and in the USA [25,26]. In particular, REE does not differ between rural Nigerians and US blacks [25] -therefore not explaining the different rates of obesity in these groups.…”

“…In particular, REE does not differ between rural Nigerians and US blacks [25] -therefore not explaining the different rates of obesity in these groups. Furthermore, after adjustment for REE, the relationships between BMI (and other measures of adiposity) and BP disappear, suggesting that metabolic processes represented by REE may mediate the effect of body size on BP [26]. Extensions of these observations to other African populations and the identification of the putative metabolic processes involved are needed.…”