In Chapter 4 I distinguished “training high” from “training low.” Training high entails consuming carbs during a run for the sake of maximizing performance in the workout. Training low entails withholding carbs during a run to increase the body’s fat-burning capacity.
Within a race-focused training cycle it is prudent to make every other week’s longest run a “fasting workout” where carbohydrate is withheld. It would be less prudent to “train low” in every long run because you would then miss out on the complementary benefits that come from attaining a higher level of performance through carbohydrate supplementation. But during a quick start I recommend doing a long fasting run once every week. Long runs undertaken at moderate intensity and without carbohydrate intake burn more fat than any other type of run you can do and thus contribute more to your goal of shedding excess body fat. These workouts will also increase your fat-burning capacity and with it your endurance, a benefit that is of secondary importance at this time.