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Is physical activity in weight management more about ‘calories in’ than ‘calories out’?

Published online by Cambridge University Press:  29 June 2011

Jean-Philippe Chaput
Affiliation:
Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, Ontario, CanadaK1H 8L1, email jpchaput@cheo.on.ca
Arya M. Sharma
Affiliation:
Division of Endocrinology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Abstract

Type
Letter to the editor
Copyright
Copyright © The Authors 2011

In the field of obesity research, physical activity has traditionally been considered a strategy to use energy. Most treadmills and exercise bikes display ‘calories’ and many people are obsessed about burning those extra ‘calories’, often only to eat or drink them right back. Although the results of exercise programmes designed to reduce body weight are generally considered disappointing, there is no doubt that some individuals can experience substantial weight loss with regular physical activity. In recent intervention studies, the same amount of supervised aerobic exercise has been shown to result in substantial weight loss in some individuals and even weight gain in others(Reference Chaput, Klingenberg and Rosenkilde1, Reference King, Hopkins and Caudwell2). Thus, there appears to be almost no relationship between the amount of energy expended during exercise and changes in body weight. For example, a 10 lb (4·5 kg) weight loss within 10 weeks of taking up an exercise programme would require the burning of 35 000 kcal (146 440 kJ), which would correspond to about 1 h of intensive aerobic exercise daily. However, as recently reviewed(Reference Chaput, Klingenberg and Rosenkilde1), physical activity is more than simply a strategy to use energy. The stimulus of exercise provides a wide range of metabolic adaptations that improve overall health and can be associated with marked reductions in abdominal fat and increases in skeletal muscle mass(Reference Ross and Bradshaw3).

In addition to the positive effects of exercise on energy expenditure and metabolism, the discussion about the benefits of exercise on weight management generally fails to acknowledge the substantial positive impact that physical activity can have on ingestive behaviour. We hypothesise that while the homeostatic system of energy regulation may well respond with a compensatory increase in hunger(Reference Hopkins, King and Blundell4), the effects of exercise on the hedonic system can lead to a substantial decrease in energy intake in some individuals. Our hypothesis is based on the evidence that numerous psychological and hedonic drivers of ingestive behaviour can potentially be positively modulated by physical activity.

In particular, the regular practice of physical activity has been shown to decrease the risk of stress-induced weight gain(Reference Chaput, Klingenberg and Rosenkilde1, Reference Holmes, Ekkekakis and Eisenmann5). Psychological benefits provided by exercise are not trivial and there is no doubt that we should aim at increasing the physical:mental activity ratio in our modern way of living(Reference Spence, McGannon and Poon6). Additionally, physical activity has been reported to improve sleep quality(Reference Brand, Gerber and Beck7). Considering that lack of sleep is itself a stressor that has been associated with weight gain(Reference Chaput, Després and Bouchard8), physical activity can have a stress-buffer effect and might improve appetite control in short-duration sleepers. Given that contemporary society is generally characterised by high levels of mental stress and impaired sleep(Reference Chaput, Klingenberg and Sjödin9), regular physical activity might help buffering these stressors and breaking the stress-feeding habits. This concept is supported by studies showing that stress-relief activities (e.g. relaxation, yoga, meditation, etc.), which do not burn a large amount of energy per se, are generally effective in reducing emotional eating episodes and reducing body weight(Reference Manzoni, Pagnini and Gorini10, Reference McIver, McGartland and O'Halloran11). Thus, therapeutic processes that occur with stress-reduction interventions have the potential to promote weight loss in some individuals despite their minimal impact on energy expenditure.

We therefore propose that a substantial proportion of the variance in the contribution of exercise on body weight can be explained by positive effects of exercise on ingestive behaviour in individuals in whom overeating is primarily driven by stress, depression, poor self-esteem or unrestorative sleep, all of which can be improved with regular exercise. Accordingly, weight loss in these individuals is more likely to be explained by the impact of exercise on energy intake rather than energy expenditure. As a corollary, physical activity is probably less likely to produce weight loss in individuals not prone to overeat for the reasons mentioned above, because it does not help them reduce their energy intake.

Our hypothesis not only helps explain the remarkable inter-individual variation in exercise-induced weight loss but also readily explains why the amount of weight that some individuals lose with physical activity appears unrelated to the actual energy expenditure.

Recognition of the important role of exercise on improving ingestive behaviour may have some very significant public health and clinical implications for physical activity recommendations. If the overall beneficial impact of physical activity on body weight is more related to stress relief, better sleep and other adaptations that affect food intake, then it may be irrelevant to measure or predict the impact of physical activity on the basis of energy used. Indeed, focusing on ‘calories burnt’ or even equating ‘calories burnt’ with the potential weight benefits of physical activity can be misleading and frustrating. In fact, most health benefits of regular physical activity, whether weight-related or not, have little to do with energy expenditure. The stress relief and well-being that results from regular physical activity can help ‘at risk’ people to eat less. Individuals highly involved in mental activities, short-duration sleepers and stressed individuals would benefit from starting a regular physical activity programme, mainly because of the impact on food intake.

We propose that exercise recommendations for weight management should be based on their potential impact on energy intake (and metabolism) rather than on energy used and should be primarily targeted at individuals with stress- or mood-related hyperphagia.

Acknowledgements

J.-P. C. holds a Junior Research Chair in Healthy Active Living and Obesity Research. A. M. S. is the Scientific Director of the Canadian Obesity Network and holds the Alberta Health Services Chair in Obesity Research and Management. The authors declare no potential conflict of interest.

References

1 Chaput, JP, Klingenberg, L, Rosenkilde, M, et al. (2010) Physical activity plays an important role in body weight regulation. J Obes (Epublication ahead of print version 12 August 2010).Google ScholarPubMed
2 King, NA, Hopkins, M, Caudwell, P, et al. (2009) Beneficial effects of exercise: shifting the focus from body weight to other markers of health. Br J Sports Med 43, 924927.Google Scholar
3 Ross, R & Bradshaw, AJ (2009) The future of obesity reduction: beyond weight loss. Nat Rev Endocrinol 5, 319326.CrossRefGoogle ScholarPubMed
4 Hopkins, M, King, NA & Blundell, JE (2010) Acute and long-term effects of exercise on appetite control: is there any benefit for weight control? Curr Opin Clin Nutr Metab Care 13, 635640.CrossRefGoogle ScholarPubMed
5 Holmes, ME, Ekkekakis, P & Eisenmann, JC (2010) The physical activity, stress and metabolic syndrome triangle: a guide to unfamiliar territory for the obesity researcher. Obes Rev 11, 492507.CrossRefGoogle Scholar
6 Spence, JC, McGannon, KR & Poon, P (2005) The effect of exercise on global self-esteem: a quantitative review. J Sport Exerc Psychol 27, 311334.CrossRefGoogle Scholar
7 Brand, S, Gerber, M, Beck, J, et al. (2010) High exercise levels are related to favourable sleep patterns and psychological functioning in adolescents: a comparison of athletes and controls. J Adolesc Health 46, 133141.Google Scholar
8 Chaput, JP, Després, JP, Bouchard, C, et al. (2008) The association between sleep duration and weight gain in adults: a 6-year prospective study from the Quebec Family Study. Sleep 31, 517523.Google Scholar
9 Chaput, JP, Klingenberg, L & Sjödin, AM (2010) Do all sedentary activities lead to weight gain: sleep does not. Curr Opin Clin Nutr Metab Care 13, 601607.CrossRefGoogle Scholar
10 Manzoni, GM, Pagnini, F, Gorini, A, et al. (2009) Can relaxation training reduce emotional eating in women with obesity? An exploratory study with 3 months of follow-up. J Am Diet Assoc 109, 14271432.CrossRefGoogle ScholarPubMed
11 McIver, S, McGartland, M & O'Halloran, P (2009) “Overeating is not about the food”: women describe their experience of a yoga treatment program for binge eating. Qual Health Res 19, 12341245.CrossRefGoogle ScholarPubMed