Calorie Cycling: What Is Calorie Cycling and Does It Work? | Ask The Fitness Nerd
Posted Mar 07 2009 10:34am
Can Calorie Cycling Help Pull Off More Body Fat and Hold On To Precious Muscle?
Dear Fitness Nerd,
I recently heard about something called “calorie cycling.” Apparently it’s a way to prevent weight loss plateaus and maybe burn additional body fat. Do you know anything about calorie cycling or how it works? Is this different from the zig-zag diet concept, or the same thing? And will it help me add more lean muscle? — Marcus (Arlington, VA)
Calorie cycling (also known as “calorie shifting” or “Zig Zag dieting”) is an approach to eating that is intended to prevent weight or fat loss plateaus by “tricking out” your metabolism.
Calorie cycling or Zig Zag diets are not really ”diets” in the sense of something like Atkins or South Beach, but instead a method of manipulating the metabolism through varying your calorie intake day-to-day.
Many people who use it report experiencing greater overall fat loss, with less frequent weight or fat loss plateaus. It also may encourage the preservation of lean muscle mass, which is always at risk during when you restrict calories to encourage loss of body fat.
Although clinical research on the effectiveness of calorie cycling versus traditional dieting methods that utilize sustained calorie deficits is sparse, people who try it anecdotally-report good results. However, this is an advanced fat loss technique that requires a fair amount of self-discipline to follow, as well as a willingness to measure food and count calories with a great deal of precision.
The Theory Behind Calorie Cycling
At its core, calorie cycling tries to solve for the body’s tendency toward homeostasis — or preserving the status quo.
Losing body fat requires forcing your body into tapping your long-term stores of energy, which are packed on in subcutaneous fat (the fat below your skin.) The only way to do this is to put yourself in a calorie-deficit. In other words, eating fewer calories than you expend each day just to keep your basic bodily functions running and fueling your activities, whether that’s working out or walking across the office.
Reduce your calories below your maintenance levels, and you’ll start to lose fat as the body goes to these sources to make up the deficit. Eat more calories than your body needs, and it will start to store the excess energy as body fat. Eat just the right amount of food, and your weight will stay the same.
Pretty simple formula: Calorie-in, calorie-out.
Why Traditional Diets Stumble: Homeostasis and Catabolism
There are two challenges, however, whenever you reduce your calories below your maintenance level for any extended period of time: catabolism and homeostasis.
Catabolism: The Enemy of Muscle
When you are in a calorie-deficit, the body doesn’t exclusively burn stored body fat to compensate for the gap. It also burns carbohydrates, and sometimes protein in the form of lean tissue.
So this means that even though you are losing scale weight and body fat, you may also be losing muscle along with it.
Muscle, unlike body fat, is metabolically-active — meaning it requires energy even at rest — so you always want to maximize it whenever possible. However, whenever you are in a calorie-deficit for any extended period of time, you will generally lose some muscle along with the fat.
Homeostasis: The Body Doesn’t Like Change!
The second issue is that eventually your body will eventually catch on that you’re eating less food than you need, and it will interpret this as a sign that it might be in for an extended period of food scarcity. So it will start to slow down your metabolism in order to conserve energy, since it interprets your calorie deficit as a sign of “famine.”
This response is programmed into your genes from millions of years of human evolution, and is intended to help you survive in a famine. As you decrease your calories, hormones are produced that regulate metabolism and lipid oxidation (fat burning), literally slowing down how much energy your body burns.
These hormones (such as the stress hormone cortisol) present a dilemma for people who are trying to lose body fat while also preserving muscle.
Cortisol is catabolic and encourages the breakdown of lean tissue. It also tells the body to actually hold on to fat stores or even increase them when it has a chance. This is not a situation that will help you get lean. In fact, it’s pretty much a dieting death spiral.
This is why people will experience fairly dramatic weight or fat loss when first beginning a diet, but then hit a wall within a few weeks, as fat loss slows.
Part of this is because as you get closer to your “ideal” weight, the body holds on even tighter to body fat as a protection against future food scarcity (those damn genes again). But the other reason is that your brain has started to slow your metabolism down as a response to the reduction in food.
This is where the dreaded diet plateau rears it’s ugly head.
Calorie Cycling To The Rescue?
Calorie cycling tries to avoid the body’s natural tendency toward homeostasis by essentially tricking it into thinking that your not actually dieting at all.
Because total fat loss isn’t necessarily about your calories on a specific day, but rather creating a total calorie deficit over a time, it’s possible to alternate days of calorie-deficits, with days of calorie-surpluses and still lose body fat.
Even better, because you alternating higher calorie days with lower calorie days, you may be less likely to lose lean tissue and less prone to developing fat loss plateaus. This can be especially effective if you match your higher-calorie days to the days when you are performing weight training, since your body can use the extra energy to fuel your workout and recovery.
While your initial fat loss results may be less dramatic on a calorie cycling diet than if you simply put yourself into a sustained calorie deficit, over time, cycling your calories may actually result in more total fat loss with less muscle catabolism.
Or at least that’s the theory.
There has actually been very little clinical research conducted on calorie cycling. So you should know that going into it.
Most of the evidence around the effectiveness of calorie cycling is anecdotal, although calorie cycling devotees often swear by the results. The main point of contention is not whether you’ll lose fat (you will if done correctly), but rather how effective it actually is tricking out your metabolism.
There may be a psychological benefit to calorie cycling that makes it more effective for certain people, as well. Some people find calorie cycling allows them to stick to their diet more easily, because you’re incorporating some “cheat days” into your diet. This can make the the calorie-deficits more tolerable.
Example of a Calorie Cycling Diet for Weight Loss
If you want to give calorie cycling a shot, you need to know a few things:
How many calories you should be eating to maintain your current weight
How many lbs of fat you want to lose during the diet
Your workout schedule and intended intensity
Once you know these things, it’s basically just a matter of figuring out how to stagger your calories across the week to produce the necessarily cumulative deficit by the end of seven days. So let’s look at an example.
Let’s say you are a 30 year old male who weighs 180 lbs at six feet tall. You workout three times a week.
You will want to eat around 2500 calories a day (or 17,500 per week) to maintain your current weight. To lose 1 lb of fat each week, you need to create a weekly deficit of 3,500 calories (1 lb of fat contains roughly 3,500 calories) which means you need to come in at around 14,000 calories for the week (17,500 - 3,500 = 14,000 calories.)
With a traditional diet, you would either eat 500 fewer calories each day or expend an addition 500 calories each day. Over seven days, that would create a total deficit of 3500 calories, which under most circumstance would cause you to lose about a pound of fat. So here’s what your daily calorie intake would look like:
You still end the week with a 3,500 calorie deficit, but you achieve that by cycling your calories up and down each day, versus keeping them steady day-over-day.
One of the nice things about this approach is that you can align the higher calorie days with your most intense workouts, and the lower calorie days with either cardio or rest days. This can help give you more energy on the days when you need it and encourage anabolism and muscle building on the days when you are training.
How To Create Your Own Calorie Cycling Diet Plan
You can create your own calorie cycling diet plan with a calculator and a little arithmetic.
You basically take your daily target for whatever your goal is (weight loss, weight gain, or maintenance) and then add a few hundred more calories in one day, while subtracting a few hundred on another day so that over seven days you are still hitting your total cumulative calorie target.
You can come up with a number of different patterns that you can try, and then see which calorie cycling routine works best for your goals.
If this all sounds too tedious, there are some nice tools available online to take the grunt work out of figuring out how to cycle the calories each day to get the necessary deficit at the end of the week. This tool does a good job of calculating a 7-day zig zag diet for you.
Challenges to Calorie Cycling
The biggest challenge to calorie cycling is the self-discipline it requires.
In general, you’ll want to be fairly precise about where you come in each day for this approach to work. You’ll need to count calories here. For how long depends on how good you are at gauging portions, but most people who report success with calorie cycling get pretty scientific with their calorie counting.
Using food and diet tracking tool like Sparkpeople.com, Fitday or Calorie King can take most of the monotony out of tracking your food intake, and will also let you see which patterns in your calorie cycling regimen work best for hitting your goals.
However, if counting calories is something you hate doing, then calorie cycling probably isn’t a particularly good option for you.
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