Losing weight and burning fat. There are numerous diets and trends out there reported to be the best way to lose weight. However, one that's rarely talked about actually has multiple studies that show its effectiveness.
It's called "Intermittent Calorie Restriction" and involves alternating periods of calorie restriction and calorie maintenance. It's said to provide improved adherence, muscle preservation, and metabolic support. This ultimately leads to greater success while maintaining your fat. Here's what you need to know.
What is Intermittent Calorie Restriction?
Intermittent calorie restriction is a structured form of alternating between a period of caloric restriction and a period of calorie maintenance.
But to be clear, this is not intermittent fasting, in which you do not eat. It simply involves alternating between periods of higher and lower calorie consumption.
Intermittent Calorie Restriction Vs. Continuous Dieting
We'll get into the research behind intermittent calorie restriction below, but we'll give a brief rundown of the supposed benefits of intermittent calorie restriction.
In total, there tend to be 3 primary benefits that counteract the possible negative effects of continuous dieting.
1. Reduce Adaptive Thermogenesis (Maintain Metabolism Levels) - If a person stays in a continuous caloric deficit for too long, they run the risk of "Metabolic Adaptation". This is when your metabolism can slow down in an attempt to decrease energy expenditure.
Often, people may refer to this as "metabolic damage," which, in most cases, it's not, as that's exactly how your metabolism is designed. Regardless, ICR can help mitigate this by breaking up long periods of caloric restriction.
Understand these changes are not massive, and if they do occur, they're usually less than 100 calories a day. Still, this can definitely add up and possibly mitigate longer-term issues.
This can possibly mitigate any possible plateaus.
2. Maintain Optimal Hormone Levels - Continuous dieting can put the body in a stressful environment. This has the potential to disrupt your hormones.
- Leptin: Drops during calorie restriction, leading to increased hunger and reduced metabolic rate; ICR helps restore it during higher-carb maintenance days.
- T3 (Thyroid Hormone): This key metabolic hormone declines with prolonged energy restriction, but periodic refeeds may help sustain its production and maintain calorie burn.
- Testosterone: Long-term dieting lowers testosterone, which can reduce muscle retention and mood; ICR helps mitigate this by reducing the duration of constant deficit stress.
- Cortisol: Prolonged restriction elevates this stress hormone, promoting muscle breakdown and fat retention, but ICR can help reduce chronic elevation by introducing recovery periods.
When combined with maintained metabolism, this can possibly lead to improved body composition, including decreased muscle loss.
3. Improve Adherence and Enjoyment - Adherence to dieting is a primary reason they aren't successful. Knowing that you're going to be hungry for 6 months can be enough to dissuade anyone from either starting or continuing a diet.
However, knowing that you are only going to go through short periods of restriction can make dieting easier and more enjoyable. This is likely the most practical benefit and exists regardless of the physiological effects.
Types Of Intermittent Calorie Restriction
While we're predominantly using the term intermittent calorie restriction, there are different types. These use slightly different dieting periods with slightly different purposes, but the primary mechanisms and science are the same.
1. Refeed Days - Short-term increases in calorie intake, usually 1-2 days, with a focus on carbohydrate intake. It’s more commonly seen in the bodybuilding community, but the basic premise is the same.
Typical structure:
- Calories at or near maintenance
- Carbs ↑, protein steady, fat ↓
- Often used once a week or every other week during a cut
2. Diet Breaks - A longer pause from dieting of around 1–2 weeks, where calories are brought fully back to maintenance.
Typical use:
- After 4–8 weeks of dieting
- Can be planned (e.g., every 6 weeks) or reactive (e.g., if progress stalls)
3. Calorie Cycling - Varying your daily calorie intake across the week, often based on activity levels.
Typical use:
- High calories on training days
- Lower calories on rest days
- Still results in a net weekly deficit
The Science Behind Intermittent Calorie Restriction
Above, we spoke about some of the basic theories of why ICR may be better than continuous calorie restriction. Now, we want to look at some actual studies.
Study 1. One of the most popular references is known as "The Matado Study" in 2018. It contained two groups of obese men, the Continuous Diet and Intermittent Restriction Diet, and lasted 16 weeks.ï±£¹³ The specific protocol was as follows;
- Continuous Diet: 16 weeks of uninterrupted dieting at 67% of maintenance
- Intermittent Restriction Diet: 2-week deficit + 2-week diet break (at maintenance), repeated 38x (30weeks total)
At the end of the study, the intermittent group had better results, including;
- Greater weight loss without greater loss of muscle
- Mitigated the reduction in REE (resting energy expenditure)
- Superior weight loss retention after 6 months
"In conclusion, intermittent ER, delivered as alternating 2-week blocks of ER and energy balance, resulted in greater weight loss (fat loss) without greater loss of FFM, attenuation of the reduction in REE, and superior weight loss retention after 6 months."
Now, it is important to note that the continuous protocol lasted almost twice as long due to the restriction being interrupted.
Study 2. A narrative review from 2020 was published on the effects of diet breaks and diet feeds for precontest prep.² It reviewed several styles of ICR but found that in general, it does show promise to be effective in;
- Preserving fat-free mass
- Maintaining resting metabolic rate
- Maintain or mitigate disruption to hormone changes
It's important to note that there was some variance between all the studies – ICR is not a magic bullet, but it can be an effective tool.
Study 3. In 2023, a study looked at the effects of diet breaks vs. continuous dieting for preserving fat-free mass and resting metabolic rate (RMR) in resistance-trained females.³
- Continuous Dieting: 6 weeks of uninterrupted 25% calorie deficit
- Intermittent Dieting: 2-week deficit + 1-week diet break (at maintenance), repeated 3x (9 weeks total)
In this study, in terms of body composition measurements, there were no significant differences between the two groups.
While this may suggest there's no physiological benefit, it can be beneficial on a psychological level.
Study 4. A large review from 2025 examined 12 trials that examined intermittent dieting vs conventional continuous energy restriction for improving body composition and attenuating metabolic adaptation.⁴
Both intermittent dieting and continuous dieting produced significant improvements in various body composition measurements, including:
- Fat mass
- Body mass index (BMI)
- Body fat percentage
- Waist circumference
However, an intermittent diet did mitigate a significant drop in RMR (resting metabolic rate). This was especially true for overweight and obese individuals.
How to Use Intermittent Calorie Restriction
If you've had trouble with dieting and think this looks promising, we'd definitely encourage you to give it a shot. The general structure isn't complicated – here's what you need to do.
1. Choose A Structure. Choose a structure that works best for you. There's not enough research to suggest one over the other, so use what fits your lifestyle and needs best.
One popular method that makes sense for many people is 5 days of restriction (the week) with 2 days of maintenance (the weekend).
2. Calculate Your Calories And Macros. Calculate your calories and macros so that you can keep track.
3. Get In a Calorie Deficit On Diet Days. On your calorie-restricting days, get into a deficit of around 20% maintenance calories.
4. Eat At Maintenance. On your maintenance days, simply eat at maintenance levels.
5. Recalculate Your BMR. Every 4-6 weeks of calorie restriction, measure your weight and fat loss. Use your date to adjust your maintenance levels and continue.
And that’s it. As we mentioned, it will take longer to lose weight as you will be taking breaks, but reaching your goal later is better than never.
Check out this 7-Day Carb Cycling Diet, Too!
Final Say On Intermittent Calorie Restriction
After looking at research on intermittent calorie restriction, it does appear to provide legitimate weight loss benefits for those not in a hurry. It can possibly mitigate any negative effects of continuous dieting and may result in a superior end result. Maybe.
Intermittent calorie restriction is not a magic diet, and there is variance in study results. At the same time, it does have the practical benefit of allowing some relief in a diet, also showing you don’t need to be in a perfect deficit every day; it’s the overall effort and consistency that matters.
Reference
- Byrne, N., Sainsbury, A., King, N. et al. Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. Int J Obes 42, 129–138 (2018). https://doi.org/10.1038/ijo.2017.206
- Escalante G, Barakat C, Torres J, Mills S, Schoenfeld BJ. Effectiveness of diet refeeds and diet breaks as a precontest strategy. Journal of the International Society of Sports Nutrition. 2020;17(1):1–7. https://www.researchgate.net/publication/339949771_Effectiveness_of_Diet_Refeeds_and_Diet_Breaks_as_a_Precontest_Strategy
- Siedler MR, Lewis MH, Trexler ET, et al. The Effects of Intermittent Diet Breaks during 25% Energy Restriction on Body Composition and Resting Metabolic Rate in Resistance-Trained Females: A Randomized Controlled Trial. J Hum Kinet. 2023;86:117-132. Published 2023 Jan 20. doi:10.5114/jhk/159960 https://pmc.ncbi.nlm.nih.gov/articles/PMC10170537/
- Poon ET, Tsang JH, Sun F, Zheng C, Wong SH. Effects of intermittent dieting with break periods on body composition and metabolic adaptation: a systematic review and meta-analysis. Nutr Rev. 2025;83(1):59-71. doi:10.1093/nutrit/nuad168 https://pubmed.ncbi.nlm.nih.gov/38193357/
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