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 Big Twin
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 Join Date: Mar 2004
 Location: South Beds
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     By gym work I mean circuit training and weights but I would also include running as well.
 
 The energy demands of these activities are too intense for the body to use fat reserves, you just use up the stored glycogen in your body, which you replace with your next meal.
 
 More gentle exercises (like walking or easy cycling) can be fuelled from fat.