Now there has been some T-nation thinking (and experimenting) on the matter a while back. Read it
here. It's called ABCD diet, the next generation, or the Delta 1250 diet. The critique is that on the original diet you put on too much fat if you gorge all out for two weeks and then diet. The author of the Delta 1250 diet proposes a bulking period of 5 days, and a cutting period of 5 days. To make this simple I quote: <div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">You'll start with a five-day underfeeding program. Simply take your bodyweight and multiply it by 12-14 calories, depending on whether you have what you consider a slow, moderate, or fast metabolism. For instance, if you have a slow metabolism and you weigh 200 pounds, multiply 200 by twelve to get 2400. That's your maintenance level. Now, during the diet phase, you'll subtract 500 calories from that to get 1900. That's how many calories you're going to ingest daily for the duration of your diet phase. Simple, huh?
Now, after the five-day underfeeding phase is up, you need to start the five-day overfeeding phase. Remember your maintenance level of calories which, in your example case, was 2400 calories? We're going to add 750 calories to that and get 3150 calories. That's how many calories you're going to ingest daily during the five-day bulking phase.
Therefore, if you look at one full, ten-day cycle with its five days of 500-calorie deficits and five days of 750-calorie excesses, you'll have ingested a total of 1250 surplus calories, or a "delta" of 1250.
</div>Sounds ok, but I still think it would be more practical to make it a full 7 days. And a 500-calorie deficit is a little small for a weeks cut. I do the numbers for you.
Case A. 7x500=3500 kcals equalling approx. 360 grams of fat (~19% of the kcals to fuel the body, if total BMR expenditure is 7x2400=16800, and 2% of the fuel comes from protein). *
Case B. A 1000 kcal restriction during 7 days would cause a loss of approx. 750 grams of fat (40% of the kcals), with a minimal loss of protein (2%).
Case C. For the daring or desperate: 800 kcals a day during a week on a PSMF diet (mix of protein and carbs - minimal fat). The fat loss is a staggering 1210 grams!! Protein loss is still at a meager 2% (that is 70 grams). You can expect your BMR to drop 12-15% during this week, so you may take this into consideration when hitting a bulking stint again. *
A 750 kcal surplus a day during one week would provide 5250 kcals extra. With heavy weight training, the favorable P-ratio would make this perhaps a 40% fat gain, equalling 230 grams.
In case B, a two week stint of cutting and bulking would result in a fat deficit of 750-230=520 grams . That is a great deal, and in the long run noticable. The other up side is that 60% of the extra calories goes into producing fat free mass. What is the delta of this? A 1750 deficit.
For case A you get a fat deficit of 360-230=130 grams. Not even noticeable!
Run case C and the numbers are foretelling a 980 grams fat cut during a cycle! The delta is minus 5950!! Do three of these hard core ABCDE cycles and cut from 15% BF to 10%! It only takes 6 weeks according to these calculations!
Is this possible? Depending on your P-ratio, current BMR and current BF% the gains and losses may give you some different numbers (In case A, an unfavorable P-ratio would mean disaster and in case C the severe deficit would make your BMR drop). What can we do to make sure the gains of fat free mass is preserved and fat gains are minimal? Make sure you get adequate protein and carbs. Minimizing fat intake to 20% (that is hard - I promise you), you will neither add that much unwanted fat into the fat depots while you have insulin surging inside from your meals (you will need fats - they are essential building blocks).
The next generation of the ABCDE diet is not impossible to make work if your calorie surplus and deficit are properly adjusted. Also, make sure to include the calorie expenditure for your workouts and other activities as the numbers used here are based on a basal metabolic rate (BMR) of 2400 kcals. Also, do not make big eyes when stepping on the scale - a great deal of the weight loss or gain will be water.
* Calculations and numbers based on empirical data from a study called
Composition of weight lost during short term weight reduction, by Yang and van Itallie.