Diet breaks: do they help you lose more fat?

A diet break is a planned return to maintenance calories, then back to the deficit. One study made that look powerful. Later work did not. The useful part is still real, and it is mostly in your head.

Short answer: In that study (men with obesity, small sample), the group who took two-week breaks at maintenance lost about 50% more fat over the period and lost a similar amount of fat-free mass. Later trials, mostly in lean, resistance-trained people and with different break schedules, found no fat-loss advantage over continuous dieting. A break still earns its place, mostly because you can keep going.

What the study compared

The study (MATADOR, 2018) ran on men with obesity, and the sample was small. It had two groups.

• Group 1: 16 weeks of dieting, eating 67% of their measured maintenance calories.
• Group 2: also 16 weeks of dieting, but after every two-week diet block they inserted 2 weeks at maintenance calories. Maintenance moves during a diet, of course. The whole thing lasted 30 weeks.

Group 2 lost about 50% more fat over that period (roughly 12 kg vs 8 kg) and lost a similar amount of fat-free mass. Six months after the diet, they were still further ahead.

A few points that sit next to that result.

• Both groups regained some fat after the diet. Group 2 did clearly better. Gaining some fat back is normal.
• Group 2 lost fat at a much better pace inside the diet blocks. Because of the maintenance blocks, their average fat loss per week was lower than group 1.
• If you know your current maintenance and you return to it during the diet, you should not gain fat. The scale will often go up 1-2 kg from water and glycogen. That is not fat, and it settles. In that study, the break group showed a smaller drop in energy expenditure than expected from their weight loss. Energy balance still decides the result.
• Careful: maintenance falls as your weight falls. If you held your weight on 2,000 kcal at the start, a few weeks later that number is lower.
• If you want to lose faster and you can live with the downsides, you do not have to change anything. The slower path has its upsides, and it is your choice.

The pace my clients can usually live with, breaks or not, is in how fast should you lose weight. What maintenance actually is, in kcal, is in calorie deficit: how much to eat.

What 2021 changed

In 2021 more studies came out. Those trials were mostly in lean, resistance-trained people and used different break schedules. They found no fat-loss advantage over continuous dieting. The breaks still have a use.

A hard week. A party. A stretch where you need a rest and you do not want to gain. When someone is losing something like 50 kg, it is not a job of a few weeks, and at some point the diet gets broken anyway. With that much to lose, keep your doctor in the loop. The break arrives on its own. How a rough week still produces a deficit is in meal planning for fat loss.

Often it is more sustainable to stop aiming at fat loss for a while. Mostly for psychological reasons, and so the method and the routine last. Fat loss is habit building. Those habits are what hold the result, and what keeps the weight from bouncing back. That bounce is in yo-yo dieting.

I read the original study as one more sign that a long change of shape should not be a sprint. You do not have to lose weight every single week. The job is to get into decent shape and then keep it.

Frequently asked questions

How did the diet-break study run?

Group 1 dieted for 16 weeks at 67% of their measured maintenance calories. Group 2 also dieted for 16 weeks, but after every two-week block they took 2 weeks at maintenance, so the whole diet lasted 30 weeks. Because of those maintenance blocks, group 2's average fat loss per week was lower than group 1's.

Will I gain fat on a diet break?

If you know your current maintenance and you eat that, you should not gain fat. The scale will often go up 1-2 kg from water and glycogen. That is not fat, and it settles. Maintenance itself drops as your weight drops.

When is a break worth it?

A hard week, a party, or a rest, when you do not want to gain. Stopping the push now and then is often what makes the method last, mostly for your head.

Sources, so you can check:

1) Byrne NM, Sainsbury A, King NA, Hills AP, Wood RE. Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. Int J Obes. 2018;42:129-138. Men with obesity, small sample. One group dieted 16 weeks at 67% of measured maintenance calories; the other dieted 16 weeks with a 2-week maintenance block after each 2-week diet block, 30 weeks in total. The break group lost about 50% more fat over that period, with a similar fat-free mass loss.

2) Later work, for example Peos JJ et al. Continuous versus intermittent dieting for fat loss and fat-free mass retention in resistance-trained adults: the ICECAP trial. Med Sci Sports Exerc. 2021. In resistance-trained adults, diet breaks gave no fat-loss advantage over continuous dieting.

Martin Barna

Online nutrition and fitness coach. Since 2013 I have coached 600+ clients. Evidence-based nutrition and training.

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This article is for information only. It is not medical advice. If you have a health condition, talk to your doctor.