Obesity and the metabolic syndrome are growing public health problems. A useful treatment is regular physical activity involving increased energy expenditure, as shown by animal studies that involved forced running or exhaustive swimming. Voluntary exercise has been shown to cause an 18 % greater reduction of body weight in rats compared to forced exercise. Another study has shown the preventive effects of green tea polyphenols against obesity.

Joshua Lambert, Pennsylvania State University, State College, PA, USA, and colleagues analyzed the effect of green-tea extract (GTE) in combination with voluntary exercise in mice fed a diet high in fat. Voluntary exercise in combination with GTE reduced the final body mass by 27.1 % and the total visceral fat mass by 36.6 % compared to mice fed a diet high in fat without treatment. GTE or voluntary exercise alone had less significant effects.
Analysis of the expression of genes related to fat metabolism in the liver showed that treatment with exercise and GTE modulate the metabolism of fatty acids by favoring the oxidation of fatty acids rather than de novo lipogenesis. Observed phenotypic changes are, therefore, probably due to an enhanced energy metabolism and decreased lipogenesis.

• Voluntary exercise and green tea enhance the expression of genes related to energy utilization and attenuate metabolic syndrome in high fat fed mice,
  Sudathip Sae-tan, Connie J. Rogers, Joshua D. Lambert,
  Mol. Nutr. Food Res. 2013.
  DOI: 10.1002/mnfr.201300621