(19-03-10) Energy deficit after exercise augments lipid mobilization but does not contribute to the exercise-induced increase in insulin sensit

Sean Alec Newsom1, Simon Schenk2, Kristin Marie Thomas1, Matthew P. Harber3, Nicolas D. Knuth1, Naila Goldenberg1, and Jeffrey F. Horowitz1*

1 University of Michigan
2 University of California, San Diego
3 Ball State University
* To whom correspondence should be addressed. E-mail: [email protected] .
The content of meals consumed after exercise can impact metabolic responses for hours and even days after the exercise session. The purpose of this study was to compare the effect of low dietary carbohydrate (CHO) vs. low energy intake in meals after exercise on insulin sensitivity and lipid metabolism the next day. Nine healthy men participated in 4 randomized trials. During the control trial (CON) subjects remained sedentary. During the other 3 trials, subjects exercised (65%VO2peak; cycle ergometer and treadmill exercise) until they expended ~800 kcal. Dietary intake during CON and one exercise trial (BAL) was designed to provide sufficient energy and carbohydrate to maintain nutrient balance. In contrast, the diets after the other 2 exercise trials were low in either CHO (LOW-CHO) or energy (LOW-EN). The morning after exercise we obtained a muscle biopsy, assessed insulin sensitivity (Si; IVGTT) and measured lipid kinetics (isotope tracers). Although subjects were in energy balance during both LOW-CHO and CON, the lower muscle glycogen concentration during LOW-CHO vs. CON (402?29 vs. 540?33 mmol/kg dw, P<0.01) coincided with a significant increase in Si (5.2?0.7 vs. 3.8?0.7 (mU/L)-1.min-1; P<0.05). Conversely, despite ingesting several hundred fewer kcals after exercise during LOW-EN compared with BAL, this energy deficit did not affect Si the next day (4.9?0.9, and 5.0?0.8 (mU/L)-1.min-1). Maintaining an energy deficit after exercise had the most potent effect on lipid metabolism, as measured by a higher plasma triacylglycerol concentration, and increased plasma fatty acid mobilization and oxidation compared with when in nutrient balance. Carbohydrate deficit after exercise, but not energy deficit, contributed to the insulin sensitizing effects of acute aerobic exercise. Whereas maintaining an energy deficit after exercise augmented lipid mobilization.

Source: J Appl Physiol (December 31, 2009). doi:10.1152/japplphysiol.01106.2009

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