Your at 15% bf and you want to lose some weight/fat in four weeks, eh? Well since you didn't state your intial tonnage we'll have to go on abstract. To do a nice job, you've left this a bit late, but since getting down to 5% is probably unreasonable in any case, lets just start with getting you down to 10% (on a 230lb guy that would be about 207lbs) which, if you have seen such, looks great and works out to just less than 1lb /day - just on the edge of safe weight loss. Besides all the good diet info. I have seen, I would stack a fat loss/thermogenic with ephedrine twice a day (for good sleep, no later than 3-4 in afternoon) . This is a bit harsh on the adrenals but if you are a healthy male you should stand it well. Next, upon waking and a bit of water do a good 45 mins of aerobics to immediately get at that fat. Eat smart and (c)lean all day and end day with another 30-45 mins of aerobics with no food after to end your day. Do this for two weeks and it should start kicking like a m'f'ker, so I would add a sunday of eat-all for the last two weeks. Not the smartest way to do things but it should work. Key will be harshly sticking to it. I think you will find that while you might not achieve your perfect 'look,' people will more than take notice. Enjoy.