Martin Berkhan is one of the few recognized experts on intermittent fasting. he recommends the lean gains protocol. this where you fast for 16 hours and you feed for 8 hours.
he wrote an article in 2010 on how to target the stubborn fat using some IF strategies. The stubborn fat is usually the lower back or lower abdomen for most people.
here is a brief excerpt from the article
“Stubborn Fat Strategies
Here are a few strategies that you should consider implementing to target stubborn fat. Keep in mind that your diet needs to be in order first and foremost. You can’t throw this into the mix and expect results if your diet is sub par.
1. Intermittent fasting. For the reasons I mentioned earlier.
2. Increase your activity level in the fasted state. Add cardio or whatever else to get your energy expenditure up. A personal favorite of mine is lower intensity and longer duration activities like walking in the 12-16 hour time interval of the fast. Not only is this the “golden age” of subcutaneous fat oxidation, but lower intensity activities selectively use fatty acids to fuel the activity. There are other reasons I favor low intensity over high intensity activities (such as HIIT). They interfere minimally with your performance in the gym and can be done on a daily basis, which is not the case with HIIT.
3. Supplementation. While I have gotten lean without thermogenics and alpha-2 receptor antagonists, such as yohimbine, they can speed up the process.
For starters: Caffeine is a dirt cheap thermogenic that will ramp up catecholamine levels. During the fast add caffeine pills and dose depending on tolerance. If you’re not a regular coffee-drinker, you can get pretty wired off 200 mg. If you’re a habitual coffee-drinker (like me), it might take up to 600 mg to even get an effect. L-Tyrosine may work synergistically with caffeine so you may consider experimenting with that as well. Personally though, I have never gotten much out of it – though many people swear by it.
For more ambitious supplementation, add the alpha-2 antagonist yohimbine or a supplement containing yohimbine in addition to caffeine pills. Take the equivalent of 0.2 mg/kg body weight shortly before fasted cardio or during the fast. This works out to 16 mg yohimbine for an 80 kg/175 lbs male if you have pure yohimbine hcl.
Other commercial thermogenics, such as Meltdown, contain 3 mg yohimbine per capsule; so you’d have to take up to 5 capsules to reach similar levels. But proceed with caution:the product says, “Never exceed more than three total capsules daily or in a single dose.” Personally, I haven’t noticed anything out of the ordinary with such dosing (>3 capsules), but I need to throw in a disclaimer here lest someone screws himself over. It would be best to start low to assess tolerance. Meltdown contains quite a few other ingredients that might make the effects stronger and more unpredictable versus straight yohimbine hcl (i.e., 5 capsules of Meltdown might be more potent than 15 mg of Y-HCL in terms of stimulatory effect and perhaps side effects).
Important: Keep in mind that insulin negates the effects of yohimbine on alpha 2-receptor inhibition. Always take it in the fasted state and never between meals. Considering the half-life of yohimbine is very short (30 min), you can also experiment with more frequent dosing during the fast. For example, three dosages taken every second hour until your first meal. In that case I would probably not recommend starting with 0.2 mg/kg, since there will be a gradual buildup of the active compound. 0.15 mg/kg is a better starting point for multiple dosages in a relatively short time frame (every second hour).
An 80 kg male could use the following schedule.
7 AM: 12 mg yohimbine.
9 AM: 12 mg yohimbine.
9 AM-10 AM: 45 to 60 min walk.
11 AM: 12 mg yohimbine.
1 PM: Meal one.”