Does it matter if I am overweight?

1. Some biomechanical, physiological and performance-related consequences.


  • Roy J. Shephard



Objective. The objective of this article is to consider the impact of obesity upon body biomechanics, physiology, and various measures of human performance and ability. Methods. Information obtained from Ovid/Medline and Google Scholar through to September 2018 was supplemented by a search of the author's personal files. Results. An excessive accumulation of body fat has a wide range of negative consequences for biomechanical and physiological functions. A few potentially positive consequences of obesity have also been suggested, but most of these supposed benefits do not withstand close examination. The mechanical efficiency of movement is impaired, with a consequent reluctance to engage in physical activity. Agility, flexibility and balance are adversely affected, with a reduction of functional capacity both at work and in leisure activities. Deposition of fat around the airways leads to sleep apnoea, predisposing to daytime sleepiness, and heat tolerance is reduced. Body fat may protect the hip bones in the event of a fall, but on the other hand a combination of relative muscle weakness with poorer agility and balance increase the risk of falls. Thermal protection is increased in cold climates, but fat offers a less flexible form of insulation than additional clothing (or external application of a layer of fat in an ultra-long distance swimmer). Brown fat plays a role in cold acclimation, but the brown fat response seems attenuated in those who are obese. The greater buoyancy of an obese person increases flotation, but this benefit is offset by a greater drag as the body rises out of the water. Even the energy reserves of fat have little practical value unless prolonged starvation is anticipated. Conclusions. There are few mechanical or physiological advantages to allowing an excessive accumulation of body fat. Given the extensive range of chronic illnesses provoked by obesity, physiological considerations certainly do not warrant ignoring the clinical imperative to maintain an optimal body mass.

Author Biography

Roy J. Shephard

Professor Emeritus, Faculty of Kinesiology & Physical Education, University of Toronto




How to Cite

Shephard, R. J. (2018). Does it matter if I am overweight? 1. Some biomechanical, physiological and performance-related consequences. The Health & Fitness Journal of Canada, 11(2), 15–52.




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