Calorie shifting is a weight loss strategy designed to combat the natural slowdown that occurs in your metabolism whenever you are restricting your calorie intake. One of the reasons we hit plateaus in our diets — unable to lose pounds for weeks and sometimes months on end — is because your body is designed to preserve its fat stores and anytime those fat stores are threatened, your metabolism slows down in order to compensate.
Our body hasn’t quite caught up with the 21st century yet and the fact that we are mostly sedentary, aren’t out chasing our food to ground , and that we live in heated homes instead of cold, drafty caves. Most of us don’t want or need this extra fat. We’re trying to get rid of it and it would be nice if nature cooperated a little bit more, but clearly we have ways to get around that. Calorie shifting is one of them.
Calorie shifting basically keeps your metabolism from becoming complacent. So instead of following, for example, a 1200 calorie diet for months on end, you provide shocks to your system so that your metabolism doesn’t expect the same thing every day. You could eat 1200 calories a day for six days and then on the 7th day, eat 3000. Another method would be to eat 1000 calories one day, 1400 the day after, 1200, 1800, etc. Or if you were following a very low carb plan, instead of changing up the number of calories, you could increase your carb consumption a couple of times a month.
Some diet plans suggest a zig zagging the ratios of carbs/proteins so that you are only eating low carb for a few days before going back to a high carb day, but you should keep in mind that a lot of the reason low carb plans actually work is because your body goes into ketosis after several days with low carb levels and this helps prevent hunger. If you zig zag every couple of days, then you will never go into ketosis. You may find that this works just fine for you, but it is something to keep in mind as you figure out the best way for your body to lose weight.