Some degree of exercise limits dangers of obesity

Walking or cycling for half an hour four times a week is sufficient to eliminate important obesity risks in adolescents. Even if they do not lose weight as a result of the exercise programme, the chances of developing diabetes appear to be significantly reduced. The relatively light exercise programmes are easy for obese adolescents to keep up. This has been revealed by research conducted by Gert-Jan van der Heijden, who will be awarded a PhD by the University of Groningen on 3 February 2010.

Obesity is a major threat to the health of adolescents. In Europe, an estimated 20 percent of children are affected and children from socioeconomically disadvantaged circumstances are particularly at risk. Obesity increases the chances of contracting type 2 diabetes, a chronic illness that can only be brought under control with difficulty (diet, change in lifestyle, medication).

Healthier despite no weight loss

Gert-Jan van der Heijden researched the health effects of a limited intensive aerobic exercise programme on both lean and obese adolescents. Fifteen obese adolescents and fourteen adolescents with a normal weight (all aged between 13 and 18 years old) spent twelve weeks cycling and/or jogging for half an hour four times a week. They did not have to change their eating habits. The obese adolescents in particular benefited significantly from the exercise programme. Although they did not lose weight, the amount of fat in the liver and around the intestines (hepatic and visceral fat accumulation) declined and insulin resistance decreased. The insulin resistance in the lean adolescents also decreased, and their muscle mass increased slightly. The amount of fat in the liver and around the intestines remained the same.

Strength training less effective

Van der Heijden also studied the effects of strength training on the health of obese adolescents. Twelve obese adolescents aged between 13 and 18 years old participated in a twelve-week programme. They had an hour’s strength training twice a week, including weight-lifting. This exercise programme resulted in an increase in muscle power and muscle mass, but their insulin resistance decreased by less than with the aerobic exercise programme. The strength training did not result in a reduction in the total amount of fat either.

Easy to achieve results

The results of the research are very hopeful. Aerobic exercise at a limited intensity appears to result in significant health gains for obese adolescents, and this group found the exercise programme easy to maintain. The participation percentage for the aerobic exercise programmes was remarkably high – 85%. However, Van der Heijden warns against excessive optimism. Although insulin resistance may have decreased in the obese adolescents, their values on this point remain much poorer than those of adolescents with a normal weight. The question is whether aerobic exercise alone will be sufficient to normalize the metabolism. However, it is a simple way of quickly achieving significant health gains.

Curriculum Vitae

Gert-Jan van der Heijden (Rotterdam, 1980) studied medicine at VU University Amsterdam. He conducted his research at the Children’s Nutrition Research Center, Baylor College of Medicine in Houston, Texas (US) in cooperation with the Beatrix Children’s Hospital of the University Medical Center Groningen (UMCG). His supervisors were Prof. A.L. Sunehag and Prof. P.J.J. Sauer. Van der Heijden is currently training to become a paediatrician at the UMCG. His thesis is entitled ‘Metabolic effects of exercise in adolescent obesity’.

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