PAPER Resting leptin responses to acute and chronic resistance training in type 2 diabetic men and women JA Kanaley 1,2 *, LM Fenicchia 1 , CS Miller 1 , LL Ploutz-Synder 1 , RS Weinstock 2 , R Carhart 2 and JL Azevedo Jr 1 1 Department of Exercise Science, Syracuse University, New York, USA; and 2 Department of Medicine, SUNY Upstate Medical University and VA Medical Center, Syracuse, New York, USA PURPOSE: To evaluate the plasma leptin levels  24 h post-exercise in control and type 2 diabetic subjects and to establish if observed changes in leptin concentrations were acute or chronic effects of a resistance training program. METHODS: Thirty men and women (17 controls and 13 type 2, obese diabetics, age 40 – 55 y) had resting blood samples drawn at 08:00 h (12 h postprandial) at the beginning of the study (pre-training), 24 h after a three repetition maximal weight lifting bout (acute) and 72 h after their last training bout of 6 weeks of resistance training (chronic). The two groups were not matched with respect to body mass index and the control subjects were not normal weight. Subjects weight-trained three times a week, for 6 weeks, for 1 h, training both the upper and lower body. RESULTS: Serum leptin concentrations were significantly higher in the type 2 diabetics than in the control group at pre-training (41.4  8.9 vs 11.4  3.0 ng=ml, P < 0.05, respectively). Compared to pre-training, the leptin levels decreased significantly (P < 0.01) after acute exercise in the diabetics but not in the control subjects (diabetics 30.9  7.1 vs controls 10.6  2.6 ng=ml). Approximately 72 h after 6 weeks of exercise training, the leptin concentrations were no longer lower than the pre-training values in either group (36.9  8.8 vs 11.9  8.8 ng=ml, respectively, P ¼ NS). When leptin concentrations were log transformed and adjusted for fat mass there were still significant changes in leptin levels over time and between the control and diabetic group (P < 0.05). CONCLUSIONS: The type 2 diabetics showed a significant 30% reduction in resting leptin levels 24 h after a single bout of resistance exercise. This was an acute response to resistance exercise and not a chronic training effect (no difference between pre-training and chronic). The decreased resting leptin concentrations  24 h post-acute exercise may be due to reduced glucose availability to the adipose tissue, particularly in the diabetic subjects. There is no chronic effect of resistance exercise on leptin concentrations. International Journal of Obesity (2001) 25, 1474 – 1480 Keywords: body composition; insulin; diabetes; gender Introduction Adipose tissue secretes leptin, a protein product of the ob gene, which is believed to act via leptin receptors on the hypothalamus and play a role in the regulation of body mass. 1,2 Although a positive relationship exists between adipose tissue mass and leptin concentrations, large varia- tions in leptin levels can be seen among individuals with similar body composition. Earlier it was believed that leptin primarily provided information about the fat stores, but more recent reports indicate that leptin concentrations may reflect energy balance. Fasting results in a decrease in plasma leptin, 3 while overfeeding increases leptin concen- trations. 1,3,4 A 7 day energy-restricted diet results in decreases in serum leptin levels, with a greater absolute decrease in women than in men. 5 However, reduction in fat energy percentage of the diet (37 to 10% for 7 weeks) 6 impacts leptin levels. Acute feeding has been shown to have no impact on leptin concentration, 7 while others suggest that meal composition may impact the postprandial leptin response. 8,9 Leptin concentrations do not explain short- term food intake regulation. 9 It is speculated that dramatic alterations in energy balance cause changes in leptin *Correspondence: JA Kanaley, 820 Comstock Ave, Rm 201, Syracuse, NY 13244, USA. E-mail: jakanale@sued.syr.edu Received 12 July 2000; revised 6 April 2001; accepted 1 May 2001 International Journal of Obesity (2001) 25, 1474–1480 ß 2001 Nature Publishing Group All rights reserved 0307–0565/01 $15.00 www.nature.com/ijo