Calorie cycling is an eating pattern that may help you stick to your diet and lose weight.
Rather than consuming a set amount of calories daily, your intake alternates.
This article explains everything you need to know about calorie cycling.
Calorie cycling, also called calorie shifting, is a dieting style that allows you to cycle between low-calorie and higher-calorie periods.
There are no food restrictions or strict guidelines, just the number of calories you can eat on certain days or weeks.
For this reason, it's not a "diet" in the conventional sense, but rather a way of structuring your weekly or monthly food intake.
Research suggests the benefits of calorie cycling include greater weight loss, improved ability to stick to a diet, less hunger and a reduction in the negative hormonal and metabolic adaptations of a normal weight loss diet (1, 2, 3).
What's more, calorie cycling can be done however it works best for you.
One of the best studies to date used a 14-day cycle. Participants did 11 days on a low-calorie diet followed by 3 days of eating more calories (termed a "refeed"). Other studies have looked at longer 3–4 week diets with 1-week refeeds (1, 2, 3).
Although this is a fairly new approach, hunter-gatherers likely had a similar eating pattern centuries ago. This is because food was not always available in the same amounts every day (4).
There were periods when food was scarce but also other times when it was abundant, depending on the time of year and hunting success (4).
Bottom Line: Calorie cycling is an eating pattern in which you cycle your calorie intake from day-to-day or week-to-week.
In order to understand why calorie cycling is so beneficial, you need to understand why conventional "diets" fail most of the time.
The fact is, the success rate for long-term weight loss is extremely poor.
One review of weight loss studies found most people regained around 60% of the weight they had lost within 12 months (5).
After 5 years, most people will likely have regained all the weight they lost, while around 30% will weigh more than their initial weight (5).
Another study found that around one-third of dieters had regained all their lost weight 1 year after the diet, with only 28 of 76 participants maintaining their new weight (6).
Bottom Line: Studies show that most dieters regain most of the weight they initially lose, and often end up weighing even more than before.
The adaptations caused by dieting suggest your body senses it as a potentially dangerous state.
Centuries ago, a low-calorie period could equate to starvation or illness.
To survive, the brain would send various signals to the body to preserve energy.
It does this via numerous biological changes, which are collectively known as "metabolic adaptations." These negative adaptations include:
- Decrease in testosterone: Testosterone is a key hormone for both genders, but especially important in men. It can decline to low levels when dieting (18, 19).
- Decrease in resting energy expenditure: This measures your metabolism or the number of calories you burn at rest. This decline is also known as adaptive thermogenesis or "starvation mode" (1, 2, 3, 16, 17, 20).
- Decrease in thyroid hormone: This hormone plays a key role in metabolism. Its levels often decline when dieting (21, 22, 23).
- Decrease in physical activity: Physical activity, both conscious and subconscious, tends to decline when dieting and may be a key factor in obesity and weight regain (24, 25, 26).
- Increase in cortisol: This stress hormone can cause many health issues and play a role in fat gain when levels are constantly elevated (27, 28, 29).
- Decrease in leptin: An important hunger hormone that is supposed to tell your brain you are full and to stop eating (30, 31).
- Increase in ghrelin: Often seen as the opposite of leptin, ghrelin is produced in the digestive tract and signals your brain that you are hungry (19, 32, 33).
These adaptations are the exact opposite of what you need for successful, long-term weight loss.
Although these changes will likely occur to some degree with calorie cycling as well, studies suggest that the effect is much smaller.
Bottom Line: A typical low-calorie diet will negatively affect hunger, hormones and metabolism. These changes make it very hard to successfully maintain weight loss in the long-term.
Your body does everything in its power to slow weight loss down, conserve energy and even regain the weight after dieting.
In one study, when participants lost 21% of their body weight, leptin levels decreased by over 70%. Another study found that 3 days of higher-calorie eating increased leptin levels by 28% and energy expenditure by 7% (31, 40).
This is one potential benefit of calorie cycling, as higher-calorie periods can reduce ghrelin and increase leptin.
For example, one study found 2 weeks of consuming 29–45% more calories decreased ghrelin levels by 18% (41).
Another study compared 3 months on a high-calorie diet to 3 months on a low-calorie diet. As expected, there was a 20% increase in ghrelin for the dieting group compared to a 17% reduction for the high-calorie group (42).
Bottom Line: Dieting causes an increase in the hunger hormone ghrelin, and a decrease in the fullness hormone leptin. Calorie cycling may help by reducing these negative hormonal adaptations.
When you cut calories, several studies have found sharp declines in the number of calories you burn per day.
As shown in the graph below, this 8-week study found almost a 250-calorie reduction in calories burned at rest (20).
Another study found a 3-week low-calorie diet decreased metabolism by over 100 calories. However, participants switched to a higher-calorie diet in the 4th week, and their metabolism increased to above starting levels (2).
Other studies have found drastic reductions of up to 500 calories per day when dieting. This is significant for weight maintenance, as you'd have to reduce your food intake by 20–25% per day just to maintain your new weight (43, 44).
Regarding testosterone, one 8-week diet and exercise routine had an extremely negative effect, reducing levels by around 60% (3).
Finally, the most relevant study used an 11-day diet followed by a 3-day high-calorie refeed and compared it to a normal diet with continuous calorie restriction (1).
Despite being allowed to eat whatever they pleased for 3 days in each 2-week period, participants lost more weight and had a lower reduction in metabolic rate (1).
Bottom Line: Research shows periodic high-calorie days can increase your metabolism and hormone levels and help you lose weight more successfully than a typical diet.
There are no definitive rules for implementing calorie cycling or higher-calorie periods.
Stick with a dietary approach that works and you like, then do these high-calorie periods intermittently.
You may want to begin a higher-calorie period after 1–4 weeks, when you notice physical changes.
These can include a decrease in energy, gym performance, sleep, sex drive or a fat loss plateau.
Diets tend to go smoothly for the first week or two, but then you experience a noticeable drop in energy, performance and quality of life.
This is when you may want to add a higher-calorie period. It's best to listen to your body and give it a few days to recover and refuel before the next mini-dieting block.
Some people enjoy having these higher-calorie days every week. For example, 5 days low-calorie and 2 days high-calorie.
Others like to get into a set routine and diet for a strict 2–4 weeks before adding in slightly longer 5–7 day high-calorie periods.
Bottom Line: Follow or pick a diet that you can enjoy and stick to, then simply add in higher-calorie refeeds every 1–4 weeks, based on your own body's feedback and results.
There is no one set cycle you must stick with.
As you can see from the studies, some people diet for 3 weeks and then have a 1-week high calorie period. Others use mini cycles, such as 11 days on and 3 days off.
Additionally, some people implement refeeds as needed, while others keep to a set schedule or cycle.
Here are a few calorie cycling protocols to consider:
- Weekend cycle: 5 days on a low-calorie diet, then a 2-day high-calorie refeed.
- Mini cycle: 11 days on a low-calorie diet followed by a 3-day high-calorie refeed.
- 3 on, 1 off: A 3-week low-calorie diet followed by a 5–7 day high-calorie refeed.
- Monthly cycle: 4–5 weeks on a low-calorie diet followed by a longer 10–14 day higher-calorie refeed.
On low-calorie days, decrease your intake by 500–1,000 calories. For the higher-calorie days, eat around 1,000 calories more than your calculated maintenance level.
Test each method and see which is best for you. If you don't count calories, simply increase your portion size or macros by around one third for the refeeds.
Bottom Line: You can try several approaches, including short 5-day diets with 2-day refeeds or longer 3–5 week diets with 1–2 week refeeds.
The varying demands of exercise can drastically change your calorie needs for that day.
Therefore, it makes sense to pair your longest and most intense exercise sessions with the high-calorie days. On the other hand, save the lighter exercise sessions or rest days for your low-calorie days.
Over time, this can allow you to lose fat but still maximize performance when it's most important.
However, don't make your routine too complex. If you just exercise for health and weight loss, you can keep it simple and follow the example protocols listed above.
Bottom Line: Base your high-calorie days and refeeds around intense training blocks or sessions, but tailor your low-calorie periods around training that's less intense or less of a priority.
Calorie cycling or shifting is a new technique that may improve dieting success.
It seems to play an important role in protecting your metabolism and hormones, which can often plummet during typical low-calorie diets.
Yet despite its benefits, it's not a magical way to lose weight.
You still need to focus on the basics, such as achieving a long-term calorie deficit, eating healthy, exercising and getting enough protein.
Once these are in place, calorie cycling can certainly help improve long-term success.