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For obese teens, intense exercise is better than moderate exercise

For obese adolescents, intense physical exercise is a promising solution for losing weight. It offers a means of slimming down without dieting!

Teenager in front of her computer with a glass of milk and bowl of cereals. © Fotolia, DURIS Guillaume
By Pascale Mollier, translated by Inge Laino
Updated on 08/09/2016
Published on 07/07/2016

A study carried out at INRA in 2015-2016 showed that when it comes to losing weight, intense cycling for 45 minutes is better than a leisurely ride that lasts twice as long. Obese teens who heed this advice can reduce their food intake by up to 31% without feeling hungry. This effect is lasting over time, as a current cohort study with 32 severely obese adolescents has shown (1). The teens, monitored over 11 months, shed between 7 and 20 kilos, depending on the individual.

Intense exercise affects gastro-intestinal peptides and the brain

Researchers found that intense physical exercise may have an effect on ghrelin, a hormone secreted by the stomach that incites people to eat (2). Intense physical exercise diminishes calorie intake by diminishing the secretion of this peptide while stimulating another gastro-intestinal antagonist peptide called PYY.

Intense exercise cures a dysfunction

Interestingly, however, this only works in obese teenagers. Indeed, intense exercise does not help normal-weight teens lose weight. According to the researchers, intense exercise corrects a dysfunction. That is, it brings ghrelin and PYY concentrations in obese individuals back to a normal level, but does not modify levels that are already normal.

Very recent findings indicate that intense physical exercise also affects the central nervous system, reducing the attention an individual pays to food.

The study opens up new avenues for tackling obesity in children without imposing diets, which is most often the stumbling block in attempts to redress an individual’s weight.

 
(1) Adolescents aged 12-15 with a body mass index of 35-36 kg/m² (80 - 135 kg).
(2) Ghrelin is a peptide that acts on a zone of the hypothalamus, the arcuate nuclei, that themselves secrete neuropeptides that affect calorie intake.

Contact(s)
Scientific contact(s):

  • David Thivel AME2P (The Laboratory of Metabolic Adaptations to Exercise in Physiological and Pathological conditions), University Clermont Auvergne
  • Beatrice Morio CarMeN Laboratory (cardiovascular, metabolism, diabetology and nutrition unit) INRA Joint Research Unit 1397, CENS Lyon
Associated Division(s):
Nutrition, Chemical Food Safety and Consumer Behaviour
Associated Centre(s):
Auvergne-Rhône-Alpes

References

Thivel D et al. 2012. The 24-h energy intake of obese adolescents is spontaneously reduced after intensive exercise: a randomized controlled trial in calorimetric chambers. PLoS One 7(1):e29840

Thivel D et al. 2012. Acute exercise and subsequent nutritional adaptations: what about obese youths? Sports Med. 42(7):607-13

Fearnbach SN et al. 2016. Reduced neural response to food cues following exercise is accompanied by decreased energy intake in obese adolescents. Int J Obes (Lond). 40(1):77-83.

Bruxelles, sculpture représantant un vélo sur laquelle est autre vélo est accroché. © INRA, NICOLAS Bertrand

Study protocol

Physical exercise is considered “intense” when it mobilises more than 70% of an individual’s average maximum capacity. The protocol used with obese adolescents (2015-2016) consisted of exercising four times a week and comparing the effects of intense exercise (cycling quickly for 45 minutes) to more moderate exercise (cycling more slowly for 90 minutes). Calorie intake was calculated based on foods consumed. The study showed that intense exercise sustainably reduces calorie intake. Levels of gastro-intestinal peptides that control calorie intake confirm this effect over time: they returned to and remained normal.  

Not to be confused: appetite and calorie intake

Calorie intake seems to be different from feeling hungry. An individual can claim to be hungry, but consume fewer calories. This is what several studies have shown since 2008. Likewise, a meta-analysis of the literature shows that physical exercise can have contradictory affects on appetite and calorie intake.