Steven Heymsfield - Academia.edu (original) (raw)

Papers by Steven Heymsfield

American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2009

Maintenance of a body weight 10% above or below that “customary” for lean or obese individuals re... more Maintenance of a body weight 10% above or below that “customary” for lean or obese individuals results in respective increases or decreases in the energy expended in low levels of physical activity (nonresting energy expenditure, NREE). These changes are greater than can be accounted for by the altered body weight or composition and are due mainly to altered skeletal muscle work efficiency at low levels of power generation. We performed biochemical analysis of vastus lateralis muscle needle biopsy samples to determine whether maintenance of an altered body weight was associated with changes in skeletal muscle histomorphology. We found that the maintenance of a 10% reduced body weight was associated with significant declines in glycolytic (phosphofructokinase, PFK) enzyme activity and, in particular, in the ratio of glycolytic to oxidative (cytochrome c oxidase, COX) enzyme activity without significant changes in the activities of enzymes relevant to mitochondrial density, respirator...

Obesity Facts, 2022

Introduction: Loss of skeletal muscle mass and function (sarcopenia) is common in individuals wit... more Introduction: Loss of skeletal muscle mass and function (sarcopenia) is common in individuals with obesity due to metabolic changes associated with a sedentary lifestyle, adipose tissue derangements, comorbidities (acute and chronic diseases) and during the ageing process. Co-existence of excess adiposity and low muscle mass/function is referred to as sarcopenic obesity (SO), a condition increasingly recognized for its clinical and functional features that negatively influence important patient-centred outcomes. Effective prevention and treatment strategies for SO are urgently needed, but efforts are hampered by the lack of a universally established SO definition and diagnostic criteria. Resulting inconsistencies in the literature also negatively affect the ability to define prevalence as well as clinical relevance of SO for negative health outcomes. Aims and Methods: The European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Association for the Study of Obe...

Clinical Nutrition, 2019

Background: Sarcopenic obesity is a clinical and functional condition characterized by the coexis... more Background: Sarcopenic obesity is a clinical and functional condition characterized by the coexistence of excess fat mass and sarcopenia. Currently, different definitions of sarcopenic obesity exist and its diagnostic criteria and cutoffs are not universally established. Therefore, the prevalence and sensitivity of this condition for any disease risk prediction is affected significantly. Aim: This work was conducted under the auspices of the European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Association for the Study of Obesity (EASO). An international expert panel performed a systematic review as an initial step to analyze and summarize the available scientific literature on the definitions and the diagnostic criteria for sarcopenic obesity proposed and/or applied in human studies to date. Methods: The present systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The search was conducted in April 2018 in three databases (PubMed, Scopus, Web of Science). Human studies conducted in both sexes, irrespective of ethnicity, and published from 2007 to 2018 were included; cohorts of individuals with obesity and

The American Journal of Clinical Nutrition, 2005

Background: Phase angle is an indicator based on reactance and resistance obtained from bioelectr... more Background: Phase angle is an indicator based on reactance and resistance obtained from bioelectrical impedance analysis (BIA). Although its biological meaning is still not clear, phase angle appears to have an important prognostic role. Objective: The aim of this study was to estimate population averages and SDs of phase angle that can be used as reference values. Design: BIA and other methods used to evaluate body composition, including hydrodensitometry and total body water, were completed in 1967 healthy adults aged 18-94 y. Phase angle was calculated directly from body resistance and reactance, and fat mass (FM) was estimated from the combination of weight, hydrodensitometry, and total body water by using the 3-compartment Siri equation. Phase angle values were compared across categories of sex, age, body mass index (BMI), and percentage FM. Results: Phase angle was significantly (P 0.001) smaller in women than in men and was lower with greater age (P 0.001). Phase angle increased with an increase in BMI and was significantly inversely associated with percentage fat in men. Phase angle was significantly predicted from sex, age, BMI, and percentage FM in multiple regression models. Conclusions: Phase angle differs across categories of sex, age, BMI, and percentage fat. These reference values can serve as a basis for phase angle evaluations in the clinical setting.

European journal of nutrition, Nov 27, 2021

The aim of this study was (1) to assess AT through 13 different mathematical approaches and to co... more The aim of this study was (1) to assess AT through 13 different mathematical approaches and to compare their results; and (2) to understand if AT occurs after moderate WL. Ninety-four participants [mean (SD); BMI, 31.1 (4.3) kg/m2; age, 43.0 (9.4) years; 34% females] underwent a 1-year lifestyle intervention (clinicaltrials.gov ID: NCT03031951) and were randomized to intervention (IG, n = 49) or control groups (CG, n = 45), and all measurements were made at baseline and after 4 months. Fat mass (FM) and fat-free mass (FFM) were measured by dual-energy X-ray absorptiometry and REE by indirect calorimetry. AT was assessed through 13 different approaches, varying in how REE was predicted and/or how AT was assessed. IG underwent a mean negative energy balance (EB) of 270 (289) kcal/day, p < 0.001), resulting in a WL of − 4.8 (4.9)% and an FM loss of − 11.3 (10.8)%. Regardless of approach, AT occurred in the IG, ranging from ~ − 65 to ~ − 230 kcal/day and three approaches showed significant AT in the CG. Regardless of approach, AT occurred after moderate WL in the IG. AT assessment should be standardized and comparisons among studies with different methodologies to assess AT must be avoided.

European Journal of Sport Science, Nov 28, 2022

Obesity Reviews, Aug 19, 2019

+ Prof. Altman contributed to this article prior to his untimely passing in June of 2018. His inc... more + Prof. Altman contributed to this article prior to his untimely passing in June of 2018. His inclusion as an author here recognizes his contributions, though he was unable to approve of the final version. Disclosures Dr. Allison has received personal payments or promises for same from: Biofortis; Fish & Richardson, P.C.; HawkPartners; IKEA; Laura and John Arnold Foundation; Law Offices of Ronald Marron; Sage Publishing; Tomasik, Kotin & Kasserman LLC; Nestec (Nestlé); WW (formerly Weight Watchers International LLC). Donations to a foundation have been made on his behalf by the Northarvest Bean Growers Association and the United Soy Bean Board. Dr. Allison is an unpaid member of the International Life Sciences Institute North America Board of Trustees. Dr. Allison's institution, Indiana University, has received funds to support his research or educational activities from: Alliance for Potato Research and Education; Dairy Management Inc.; Herbalife; and the NIH. His prior institution, the University of Alabama at Birmingham, received grants, gifts or contracts from multiple food, beverage, and other for profit and non for profit organizations with interests in obesity, statistical methods, and research design. Dr. Baranowski discloses being employed by Baylor College of Medicine, his institution having NIH grants for his work, and having received speaking fees from the University of Georgia. Dr. Bland discloses that topics presented herein are related to a textbook for which he receives royalties; and has received travel accommodations from the University of Western Ontario and for the Health Services Research Board Senior Investigator Award. Dr. Brown has received travel expenses from

Scandinavian Journal of Medicine & Science in Sports, 2021

We aimed to validate bioelectrical impedance spectroscopy (BIS), compared with tracer dilution me... more We aimed to validate bioelectrical impedance spectroscopy (BIS), compared with tracer dilution measurements, for assessing total body water (TBW), intracellular water (ICW), and extracellular water (ECW) in athletes differing in hydration status. A total of 201 athletes participated. Reference TBW and ECW were determined by deuterium and bromide dilution methods, respectively; ICW was calculated as TBW‐ECW. Water compartments were estimated by BIS. Urine specific gravity (USG) classified athletes into well‐hydrated (WH) (USG < 1.023), euhydrated (EH) (USG:1.024–1.026), and dehydrated (DH) (USG>1.027). No significant differences were found between BIS and the reference methods for WH, EH, and DH athletes for TBW, ICW nor ECW (p>0.05). Concordance of TBW and its compartments by method was significant (p < 0.001) with coefficients of determination ranging by hydration classification [EH:52–96%;DH:56–98%;WH:71–96%]. Bland‐Altman analyses showed no trend for TBW and its compa...

European Journal of Sport Science, 2019

Bioelectrical impedance(BI) has been widely used but clarification about the behavior of raw BI m... more Bioelectrical impedance(BI) has been widely used but clarification about the behavior of raw BI measurements under specific athletic conditions is required. Thus, we determined the usefulness of raw BI measures in tracking body fluids changes during the preparation period prior to competition in elite Judo athletes. At baseline (weight stability), 27 male athletes were evaluated (23.2±2.8y) and again 1-3 days before competition (~1-2 months apart). Athletes were free to gain/lost weight based upon specific competition needs. Using dilution techniques (deuterium and bromide), total-body water(TBW) and extracellular water were estimated, and intracellular water calculated as TBW minus extracellular water. Body fluid distribution was determined as Extra-to-/Intracellular water(E/I). Fat and fat-free mass(FFM) was assessed by dual-energy x-ray absorptiometry. Resistance, reactance, and phase angle(PhA) were obtained from bioelectrical impedance spectroscopy (50-kHz frequency). No differences in raw BI measures were observed between athletes that lost (N=17) or gain weight (N=10), except for fat, FFM, extracellular water, and EI(p<0.05). After adjusting for FFM and height, resistance explained TBW(ß=-0.047, p=0.002) and extracelular water(ß=-0.025, p=0.001). Reactance explained ECW(ß=-0.098, p=0.004) and EI(ß=-0.004, p=0.006), while PhA predicted TBW(ß=1.609, p=0.047), ICW(ß=1.899, p=0.001) and EI(ß=-0.056, p=0.001). Regardless of body composition changes, athletes who increase reactance and resistance reduced extracellular water and body fluids while those who raised PhA increased intracellular water. Judo athletes who reduced weight, decreased FFM but cellular health was not compromised, as PhA remained stable and, consequently, cell hydration.

The Journal of Nutrition, 1998

Although elements are the foundation of the human body, information concerning the atomic level o... more Although elements are the foundation of the human body, information concerning the atomic level of body composition is still limited. The aim of this study was to explore potentially constant relationships among elements found in vivo. Based on the known stoichiometries of relevant chemical components, a theoretical model was derived, suggesting the existence of a relatively constant ratio of total body oxygen to carbon-free body mass (TBO/CFM) in men. Eight elements (C, H, N, Ca, P, K, Na and Cl) were measured in 22 healthy male subjects by using in vivo neutron activation-40 K whole-body counting, and TBO was calculated as the difference between body mass and the sum of the eight measured elements. TBO (in kg) was significantly correlated with CFM (in kg): TBO Å 0.829 1 CFM 0 1.8; r Å 0.998, P õ 0.001, standard error of estimate Å 0.4 kg. The ratio of TBO to CFM was relatively constant, mean { SD at 0.800 { 0.009 with a CV of 1.1%. Oxygen and carbon are the two most abundant elements in the human body. The discovery of a constant relationship between oxygen and carbon is not only helpful for understanding the atomic level of body composition, but also provides the possibility of estimating the content of specific elements in vivo.

Obesity Reviews, 2019

SummaryBeing able to draw accurate conclusions from childhood obesity trials is important to make... more SummaryBeing able to draw accurate conclusions from childhood obesity trials is important to make advances in reversing the obesity epidemic. However, obesity research sometimes is not conducted or reported to appropriate scientific standards. To constructively draw attention to this issue, we present 10 errors that are commonly committed, illustrate each error with examples from the childhood obesity literature, and follow with suggestions on how to avoid these errors. These errors are as follows: using self‐reported outcomes and teaching to the test; foregoing control groups and risking regression to the mean creating differences over time; changing the goal posts; ignoring clustering in studies that randomize groups of children; following the forking paths, subsetting, p‐hacking, and data dredging; basing conclusions on tests for significant differences from baseline; equating “no statistically significant difference” with “equally effective”; ignoring intervention study results ...

International Journal of Sports Physiology and Performance, 2019

Purpose:To analyze the association between body fluid changes evaluated by bioelectrical impedanc... more Purpose:To analyze the association between body fluid changes evaluated by bioelectrical impedance vector analysis and dilution techniques over a competitive season in athletes.Methods:A total of 58 athletes of both sexes (men: age 18.7 [4.0] y and women: age 19.2 [6.0] y) engaging in different sports were evaluated at the beginning (pre) and 6 months after (post) the competitive season. Deuterium dilution and bromide dilution were used as the criterion methods to assess total body water (TBW) and extracellular water (ECW), respectively; intracellular water (ICW) was calculated as TBW–ECW. Bioelectrical resistance and reactance were obtained with a phase-sensitive 50-kHz bioelectrical impedance analysis device; bioelectrical impedance vector analysis was applied. Dual-energy X-ray absorptiometry was used to assess fat mass and fat-free mass. The athletes were empirically classified considering TBW change (pre–post, increase or decrease) according to sex.Results:Significant mean vect...

Obesity Reviews, 2018

SummaryHumans expend energy at rest (REE), and this major energy exchange component is now usuall... more SummaryHumans expend energy at rest (REE), and this major energy exchange component is now usually estimated using statistical equations that include weight and other predictor variables. While these formulas are useful in evaluating an individual's or group's REE, an important gap remains: available statistical models are inadequate for explaining underlying organ‐specific and tissue‐specific mechanisms accounting for resting heat production. The lack of such systems level REE prediction models leaves many research questions unanswered. A potential approach that can fill this gap began with investigators who first showed in animals and later in humans that REE reflects the summated heat production rates of individual organs and tissues. Today, using advanced imaging technologies, REE can be accurately estimated from the measured in vivo mass of 10 organ‐tissue mass components combined with their respective mass‐specific metabolic rates. This review examines the next frontie...

European Journal of Clinical Nutrition, 2018

Body mass in humans and animals is strongly associated with the rate of heat production as define... more Body mass in humans and animals is strongly associated with the rate of heat production as defined by resting energy expenditure (REE). Starting with the ancient Greeks up to the present time philosophers and scientists have endeavored to understand the nature and sources of body heat. Today we recognize that body mass consists of organs and tissues, each of which produces a specified amount of heat at rest. An individual organ's REE can now be estimated in vivo as the product of its assumed mass-specific metabolic rate and its imaging-derived mass; whole-body REE reflects the sum of organ and tissue metabolic rates. The sizes of organs present and total body mass in adults are governed by two main factors, a person's stature or height, and their level of adiposity. With greater body size, as represented by adult height independent of adiposity, organs remain stable or increase in mass according to distinct "scaling" patterns. Similarly, with greater relative adiposity organs adaptively accommodate to the increase in imposed mechanical and metabolic loading conditions. Through a detailed analysis of these stature and adiposity effects we show how classical statistical REE prediction models can be mechanistically understood at the anatomic body composition level.

American Journal of Physiology-Endocrinology and Metabolism, 2001

Intramuscular water content is assumed to be constant in humans independent of their anthropometr... more Intramuscular water content is assumed to be constant in humans independent of their anthropometric characteristics. To verify whether this assumption is correct, intramuscular water, proteins, glycogen, and both total and intramyocytic triglycerides were measured in 51 samples of rectus abdominis muscle obtained from 16 lean and 35 overweight and obese subjects (body mass index cutoff 24.9 kg/m2). Data (referred to as wet tissue) were analyzed by means of a composition model at the cellular level of the skeletal muscle (SM). The average SM water content was 76.3 ± 3.3% in normal-weight individuals and 65.7 ± 5.8% in obese subjects ( P < 0.0001). Total triglycerides were 5.5 ± 2.3% in controls and 19.0 ± 7.0% in obese subjects ( P < 0.0001). The intramyocytic triglyceride fraction was also increased in obese subjects. The composition model provides an explanation for the negative correlation between total triglycerides and intramuscular water, and some of the model parameters ...

Journal of Applied Physiology, 1998

Baumgartner, Richard N., Robert Ross, and Steven B. Heymsfield. Does adipose tissue influence bio... more Baumgartner, Richard N., Robert Ross, and Steven B. Heymsfield. Does adipose tissue influence bioelectric impedance in obese men and women? J. Appl. Physiol.84(1): 257–262, 1998.—Bioelectric-impedance analysis overestimates fat-free mass in obese people. No clear hypotheses have been presented or tested that explain this effect. This study tested the hypothesis that adipose tissue affects measurements of resistance by using data for whole body and body segment resistance and by using muscle, adipose tissue, and bone volumes from magnetic resonance imaging for 86 overweight and obese men and women (body mass index >27 kg/m2; age 38.5 ± 10.2 yr). In multiple-regression analysis, muscle volumes had strong associations with resistance, confirming that the electric currents are conducted primarily in the lean soft tissues. Subcutaneous adipose tissue had a slight but statistically significant effect in women, primarily for the leg, suggesting that adipose tissue can affect measured re...

American Journal of Physiology-Endocrinology and Metabolism, 2000

The relationship between resting energy expenditure (REE) and metabolically active fat-free mass ... more The relationship between resting energy expenditure (REE) and metabolically active fat-free mass (FFM) is a cornerstone in the study of physiological aspects of body weight regulation and human energy requirements. Important questions, however, remain unanswered regarding the observed linear REE-FFM association in adult humans. This led us to develop a series of REE-body composition models that provide insights into the widely used simple linear REE-FFM prediction model derived experimentally in adult humans. The new models suggest that the REE-FFM relationship in mammals as a whole is curvilinear, that a segment of this function within a FFM range characteristic of adult humans can be fit with a linear equation almost identical to that observed from a composite review of earlier human studies, and that mammals as a whole exhibit a decrease in the proportion of FFM as high metabolic rate organs with greater FFM. The present study thus provides a new approach for examining REE-FFM re...

F1000Research, 2018

Presently, control of body weight is assumed to exist, but there is no consensus framework of bod... more Presently, control of body weight is assumed to exist, but there is no consensus framework of body weight homeostasis. Three different models have been proposed, with a “set point” suggesting (i) a more or less tight and (ii) symmetric or asymmetric biological control of body weight resulting from feedback loops from peripheral organs and tissues (e.g. leptin secreted from adipose tissue) to a central control system within the hypothalamus. Alternatively, a “settling point” rather than a set point reflects metabolic adaptations to energy imbalance without any need for feedback control. Finally, the “dual intervention point” model combines both paradigms with two set points and a settling point between them. In humans, observational studies on large populations do not provide consistent evidence for a biological control of body weight, which, if it exists, may be overridden by the influences of the obesogenic environment and culture on personal behavior and experiences. To re-address...

The American Journal of Clinical Nutrition, 1996

The study of human body composition is now a distinct research area consisting of three interconn... more The study of human body composition is now a distinct research area consisting of three interconnected parts: the five-level model and associated rules that govern the relations between components, body-composition methodology, and biological factors that influence body composition. In this overview we summarize fundamental concepts that relate to the five-level model and body-composition methods. We show how these concepts can be used to outline the essential features needed to critically evaluate the bioelectrical impedance analysis method. Body-composition research is a rapidly expanding area and indepth systematic evaluation of new methods is a vital aspect of the field's growth.