scholarly journals Challenges in the study of causation of obesity

2008 ◽  
Vol 68 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Thorkild I. A. Sørensen
Keyword(s):  
Weight Gain ◽  
Energy Balance ◽  
Driving Forces ◽  
Environmental Influences ◽  
Energy Balance Equation ◽  
Balance Model ◽  
Net Energy ◽  
Weight Changes ◽  
Obesity Epidemic ◽  
Long Time

Use of the energy balance equation for understanding the causation of obesity is discussed. Its basis on the thermodynamic laws is expressed in mathematical models for body-weight changes. Only a very small net energy surplus per time unit constitutes the energy deposition during weight gain, making measurements of its components difficult. The physical laws provide exact quantitative relationships between energy intake, energy expenditure and deposition of energy, but cannot disentangle the initiating and driving forces of the energy imbalance, which may also be an active storage of fat in adipose tissue. These and various other limitations of the energy balance model warrant cautiousness in using the model in studies of obesity causation. Weight gain may be self-promoting and mathematical feedback models allowing estimation of such effects show that they are realistic. Predisposition and susceptibility should be distinguished, and susceptibility as a modifiable predisposition, the genetic and environmental contribution to predisposition and its usefulness as targets for prevention and treatment are discussed. Current progress in unravelling genetic predisposition, the complex genetically-determined mechanisms, the slower progress in unravelling the environmental influences, the different nature of genetic and environmental influences, the possible pathways of environmental influences and the environmental influences as mediators of genetic effects are addressed. The evidence behind the prevailing concept of the ‘obesogenic’ environment is critically analysed. Finally, particular opportunities for the identification of the causes of the obesity epidemic by detailed analysis of an observed irregular development of the epidemic over long time periods are presented, and evidence for predisposition as a result of postnatal environmental influences is inferred from these studies.

scholarly journals Sea-ice mechanical energy balance: nearshore Chukchi Sea, 1982

1991 ◽  
Vol 15 ◽  
pp. 63-72
Author(s):  
Robert S. Pritchard
Keyword(s):  
Energy Balance ◽  
Sea Ice ◽  
Balance Equation ◽  
Driving Forces ◽  
Chukchi Sea ◽  
Mechanical Energy ◽  
Power Input ◽  
Energy Balance Equation ◽  
Momentum Balance ◽  
Momentum Balance Equation

The mechanical energy balance of sea ice provides information about ice dynamic behavior, driving forces and the constitutive law. The energy balance equation, formed as the product of ice velocity with the ice momentum balance equation, describes changes to the kinetic and potential energy densities as power is input to the ice by wind and current. The momentum balance equation may also be used to describe the ice-stress divergence, air stress, and water stress, but the scalar form of the energy balance is simpler to understand. This paper provides new interpretations of several terms in the energy balance equation, in particular power input by air and water stress and by sea-surface tilt. Barometric pressure fields and drifting buoys deployed on the Chukchi Sea ice cover during 1982 provide wind, ice motion and current measurements that allow each term in the energy balance equation to be evaluated as a function of time. Magnitudes of power input by wind and current show how the energy balance is decomposed and help describe the relative importance of these driving forces. In the nearshore Chukchi Sea during February, March and April 1982, both wind and current provided significant forcing of the ice. Ice stress was also important and, at times, dominated other terms in the mechanical energy balance.

Effects of ad libitum food intake, insufficient sleep and weekend recovery sleep on energy balance

SLEEP ◽  
2021 ◽  
Author(s):  
Christopher M Depner ◽  
Edward L Melanson ◽  
Robert H Eckel ◽  
Janine A Higgins ◽  
Bryan C Bergman ◽  
...  
Keyword(s):  
Weight Gain ◽  
Energy Balance ◽  
Controlled Trial ◽  
Sleep Restriction ◽  
Positive Energy ◽  
Control Group ◽  
Weight Changes ◽  
Insufficient Sleep ◽  
Recovery Sleep ◽  
Ad Libitum

Abstract Study Objectives Insufficient sleep is believed to promote positive energy balance (EB) and weight-gain. Increasing weekend sleep duration to “recover” from weekday sleep loss is common, yet little is known regarding how weekend recovery sleep influences EB. We conducted a randomized controlled trial to assess how: 1) 2 days and 8 days of insufficient sleep and 2) ad libitum weekend recovery sleep impact EB (energy intake [EI] – energy expenditure [EE]). Methods Following ten baseline days with 9h per night sleep opportunities, participants completed one of three 10-day experimental protocols with ad libitum EI: control (9h sleep opportunities; n=8; 23±5y [mean±SD]); sleep restriction (SR; 5h sleep opportunities; n=14; 25±5y); sleep restriction with weekend recovery sleep (SR+WR; 5 days insufficient sleep, 2 days ad libitum weekend recovery sleep, 3 days recurrent insufficient sleep; n=14; 27±4y). Results 24h EB increased (P < 0.001; main effect) by an average of 797.7±96.7 (±SEM) kcal during the 10-day experimental protocol versus baseline with no significant differences between groups. Percent change from baseline in 24h-EE was higher (P < 0.05) on day 2 of insufficient sleep (SR and SR+WR groups; 10±1%) versus adequate sleep (control group; 4±3%). Conclusions In this between-group study, the effects of adequate sleep and insufficient sleep, with or without or weekend recovery sleep, on 24h-EB were similar. Examining EB and body weight changes using within-subject cross-over designs and “free-living” conditions outside the laboratory (e.g., sleep extension) are needed to advance our understanding of the links between insufficient sleep, weekend recovery sleep and weight-gain.

scholarly journals Long-time behavior of state functions for climate energy balance model

2017 ◽  
Vol 22 (5) ◽  
pp. 1887-1897 ◽  
Author(s):  
Nataliia V. Gorban ◽  
◽  
Olha V. Khomenko ◽  
Liliia S. Paliichuk ◽  
Alla M. Tkachuk ◽  
...  
Keyword(s):  
Energy Balance ◽  
Energy Balance Model ◽  
Balance Model ◽  
Time Behavior ◽  
Long Time Behavior ◽  
Long Time ◽  
State Functions

scholarly journals Energy Balance of Rural Ecosystems In India

2014 ◽  
Vol XL-8 ◽  
pp. 411-417 ◽  
Author(s):  
A. Chhabra ◽  
V. Madhava Rao ◽  
R. R. Hermon ◽  
A. Garg ◽  
T. Nag ◽  
...  
Keyword(s):  
Energy Balance ◽  
High Resolution ◽  
Primary Production ◽  
Geographical Location ◽  
Integrated Approach ◽  
High Energy ◽  
Balance Model ◽  
Net Energy ◽  
Output Analysis ◽  
Rural Ecosystem

India is predominantly an agricultural and rural country. Across the country, the villages vary in geographical location, area, human and livestock population, availability of resources, agricultural practices, livelihood patterns etc. This study presents an estimation of net energy balance resulting from primary production vis-a-vis energy consumption through various components in a "Rural Ecosystem". Seven sites located in different agroclimatic regions of India were studied. An end use energy accounting "Rural Energy Balance Model" is developed for input-output analysis of various energy flows of production, consumption, import and export through various components of crop, trees outside forest plantations, livestock, rural households, industry or trade within the village system boundary. An integrated approach using field, ancillary, GIS and high resolution IRS-P6 Resourcesat-2 LISS IV data is adopted for generation of various model inputs. The primary and secondary field data collection of various energy uses at household and village level were carried out using structured schedules and questionnaires. High resolution multi-temporal Resourcesat-2 LISS IV data (2013–14) was used for generating landuse/landcover maps and estimation of above-ground Trees Outside Forests phytomass. The model inputs were converted to energy equivalents using country-specific energy conversion factors. A comprehensive geotagged database of sampled households and available resources at each study site was also developed in ArcGIS framework. Across the study sites, the estimated net energy balance ranged from −18.8 Terra Joules (TJ) in a high energy consuming Hodka village, Gujarat to 224.7 TJ in an agriculture, aquaculture and plantation intensive Kollaparru village, Andhra Pradesh. The results indicate that the net energy balance of a Rural Ecosystem is largely driven by primary production through crops and natural vegetation. This study provides a significant insight to policy relevant recommendations for Energy Sustainable Rural India.

scholarly journals A multi-etiological model of childhood obesity: a new biobehavioral perspective for prevention?

2019 ◽  
Vol 45 (1) ◽  
Author(s):  
Giuliana Valerio ◽  
Sergio Bernasconi
Keyword(s):  
Childhood Obesity ◽  
Energy Balance ◽  
Energy Balance Model ◽  
Balance Model ◽  
Biological Models ◽  
Prevention Strategies ◽  
Obesity Epidemic

AbstractCurrent prevention strategies focusing only around the energy balance model have been found insufficient to tackle the childhood obesity epidemic. Originating from the paper by Baranowski et al., recently published in Current Nutrition Report, this Commentary is aimed at discussing the complex etiology of obesity, on the ground of new biological models, which open a novel biobehavioral perspective of prevention.

scholarly journals Measuring and Modelling Snowmelt in Dyrdalen, Western Norway, 1979 and 1980

1981 ◽  
Vol 12 (4-5) ◽  
pp. 235-246
Author(s):  
Knut Harstveit
Keyword(s):  
Energy Balance ◽  
Wind Speed ◽  
Sensible Heat Flux ◽  
Weather Conditions ◽  
Energy Balance Equation ◽  
Balance Model ◽  
Turbulent Heat ◽  
Net Radiation ◽  
Turbulent Heat Exchange ◽  
Empirical Constants

During spring snowmelt 1979 and 1980 the runoff from the snowpack was recorded by lysimetry from a 9 m2 area. Wind speed, air temperature, air humidity, radiation, and precipitation data were also recorded. When the melting rate (= snowpack runoff-rainfall) and the net radiation were measured, the turbulent heat exchange between the snowpack and the atmosphere was computed as a residual from the energy balance equation of the snowpack. These computed values were used to find “optimal” empirical constants in aerodynamical equations expressing the turbulent fluxes as functions of the wind speed and the temperature/vapour pressure differences between the measurements 2 m above the ground (0.6-1.5 m above the snow surface) and the values at the surface. These empirical constants agree reasonably well with constants found by other investigators. Averaged over the two melting seasons, sensible heat flux represents 65%, and net radiation represents 35% of the energy consumed in melting, while 13% was gained from condensation, and 13% was lost by evaporation. When the weather conditions varied during the melting season, the energy balance model yields better results than does the degree-day-model. Residual errors were 7.3 mm (42%) and 13.2 mm (76%), respectively. The maximum melting observed in 24 hours was 110 mm, and the snowmelt rate in overcast days was about 3 times the rate when the cloudiness was light, provided the same wind and temperature conditions and albedo ~ 70%.

scholarly journals Sea-ice mechanical energy balance: nearshore Chukchi Sea, 1982

1991 ◽  
Vol 15 ◽  
pp. 63-72
Author(s):  
Robert S. Pritchard
Keyword(s):  
Energy Balance ◽  
Sea Ice ◽  
Balance Equation ◽  
Driving Forces ◽  
Chukchi Sea ◽  
Mechanical Energy ◽  
Power Input ◽  
Energy Balance Equation ◽  
Momentum Balance ◽  
Momentum Balance Equation

The mechanical energy balance of sea ice provides information about ice dynamic behavior, driving forces and the constitutive law. The energy balance equation, formed as the product of ice velocity with the ice momentum balance equation, describes changes to the kinetic and potential energy densities as power is input to the ice by wind and current. The momentum balance equation may also be used to describe the ice-stress divergence, air stress, and water stress, but the scalar form of the energy balance is simpler to understand. This paper provides new interpretations of several terms in the energy balance equation, in particular power input by air and water stress and by sea-surface tilt. Barometric pressure fields and drifting buoys deployed on the Chukchi Sea ice cover during 1982 provide wind, ice motion and current measurements that allow each term in the energy balance equation to be evaluated as a function of time. Magnitudes of power input by wind and current show how the energy balance is decomposed and help describe the relative importance of these driving forces. In the nearshore Chukchi Sea during February, March and April 1982, both wind and current provided significant forcing of the ice. Ice stress was also important and, at times, dominated other terms in the mechanical energy balance.

scholarly journals Dynamic energy-balance model predicting gestational weight gain

2011 ◽  
Vol 95 (1) ◽  
pp. 115-122 ◽  
Author(s):  
Diana M Thomas ◽  
Jesus E Navarro-Barrientos ◽  
Daniel E Rivera ◽  
Steven B Heymsfield ◽  
Carl Bredlau ◽  
...  
Keyword(s):  
Weight Gain ◽  
Energy Balance ◽  
Gestational Weight Gain ◽  
Energy Balance Model ◽  
Balance Model ◽  
Gestational Weight

scholarly journals The Importance of Energy Balance

2010 ◽  
Vol 9 (2) ◽  
pp. 111 ◽  
Author(s):  
James O Hill ◽  
Holly R Wyatt ◽  
John C Peters ◽  
◽  
◽  
...  
Keyword(s):  
Weight Gain ◽  
Energy Balance ◽  
Energy Expenditure ◽  
Energy Intake ◽  
Weight Regain ◽  
Regulatory System ◽  
Obesity Epidemic ◽  
Treatment Of Obesity ◽  
Behaviour Changes ◽  
Developed World

Globally, bodyweight and obesity are rising in both the developing and developed world. To maintain a stable bodyweight, energy intake must, over time, exactly equal energy expenditure, a state known as energy balance. An understanding of the physiologic control of energy balance may be useful for designing interventions to tackle the obesity epidemic worldwide. Obesity occurs when the body’s energy balance is positive (i.e. when energy intake exceeds energy expenditure). Human physiology is biased towards maintaining energy balance at high levels of energy intake and expenditure. As a result, strategies to combat obesity should include a focus on increasing physical activity along with strategies for modifying food intake. An understanding of energy balance leads to the conclusion that prevention of weight gain should be easier than treatment of obesity. Components of energy balance are interdependent, and weight loss requires major behaviour changes, which trigger compensatory decreases in energy expenditure that facilitate weight regain. Prevention of weight gain can be accomplished by smaller behaviour changes. In addition to being easier to sustain than larger behaviour changes, smaller ones produce less compensation by the energy balance regulatory system. It has been estimated that relatively small changes in energy intake and expenditure totaling 100 kcal per day could arrest weight gain in most people. Interventions that advocate small changes have shown promising levels of success.

scholarly journals The Importance of Energy Balance

2013 ◽  
Vol 09 (01) ◽  
pp. 27 ◽  
Author(s):  
James O Hill ◽  
Holly R Wyat ◽  
John C Peters ◽  
◽  
◽  
...  
Keyword(s):  
Weight Gain ◽  
Energy Balance ◽  
Energy Expenditure ◽  
Energy Intake ◽  
Weight Regain ◽  
Regulatory System ◽  
Behavior Changes ◽  
Obesity Epidemic ◽  
Treatment Of Obesity ◽  
Developed World

Globally, bodyweight and obesity are rising in both the developing and developed world. To maintain a stable bodyweight, energy intake must, over time, exactly equal energy expenditure, a state known as energy balance. An understanding of the physiologic control of energy balance may be useful for designing interventions to tackle the obesity epidemic worldwide. Obesity occurs when the body’s energy balance is positive (i.e. when energy intake exceeds energy expenditure). Human physiology is biased toward maintaining energy balance at high levels of energy intake and expenditure. As a result, strategies to combat obesity should include a focus on increasing physical activity along with strategies for modifying food intake. An understanding of energy balance leads to the conclusion that prevention of weight gain should be easier than treatment of obesity. Components of energy balance are interdependent, and weight loss requires major behavior changes, which trigger compensatory decreases in energy expenditure that facilitate weight regain. Prevention of weight gain can be accomplished by smaller behavior changes. In addition to being easier to sustain than larger behavior changes, smaller ones produce less compensation by the energy balance regulatory system. It has been estimated that relatively small changes in energy intake and expenditure totaling 100 kcal per day could arrest weight gain in most people. Interventions that advocate small changes have shown promising levels of success.

Sign in / Sign up

Export Citation Format

Share Document