How long should a diet break last?

The trials used one or two weeks. MATADOR used 2-week breaks after every 2 weeks of dieting. ICECAP used 1-week breaks after every 3 weeks. No trial has compared break lengths directly, so the best length is not known.

Will I gain fat during a diet break?

Not if you eat at maintenance. In the MATADOR trial, mean weight change during the seven 2-week break blocks was 0.0 kg. Scale weight can still rise for a few days from extra food volume, glycogen, and water.

Is a refeed day the same as a cheat day?

No. In the Campbell trial, a refeed was a planned increase in carbohydrate on two consecutive days each week. A cheat day has no calorie target. No randomized trial here tested unplanned cheat days.

Is intermittent dieting the same as intermittent fasting?

No. Intermittent dieting alternates weeks of a calorie deficit with weeks at maintenance. Intermittent fasting limits eating to set hours or sets very low calorie days each week. A one-year trial of 332 adults found similar weight loss with a 5:2 plan, week-on week-off dieting, and continuous dieting.

Do diet breaks fix a weight loss plateau?

The trials did not test that. They compared planned breaks from the start of a diet, not breaks added after a stall. A plateau often means your maintenance needs are lower at your new weight.

Do Diet Breaks and Refeed Days Help You Lose More Fat?

The short answer: Probably not, for most people. One trial in men with obesity found more fat loss with 2-week diet breaks. Trials in people who lift weights found the same fat loss with or without breaks. A meta-analysis of 12 randomized trials found no significant difference in fat mass, but a smaller drop in resting metabolic rate with breaks. Breaks may lower hunger, and they make the diet longer.

What are diet breaks and refeed days?

Both are planned pauses in a calorie deficit. Researchers call the approach intermittent energy restriction, or intermittent dieting. The trials below used two forms:

Diet break. One or two weeks of eating at energy balance (maintenance calories), placed between blocks of dieting.
Refeed. One or two days of higher carbohydrate intake each week, with the deficit on the other days.

A diet break is not a week of unrestricted eating. In the trials, the break calories were set to hold weight steady.

The idea comes from metabolic adaptation. In a long deficit, the body burns less energy than the loss of body mass predicts, and hunger rises. Our guide to metabolic adaptation explains the mechanism. The hypothesis is that a pause at maintenance reverses some of that response. The trials test that hypothesis.

What did the MATADOR trial find?

MATADOR is the trial behind most diet break advice. Researchers in Australia randomized 51 men with obesity to two groups. Both groups did 16 weeks of dieting at 67% of their maintenance needs.

The continuous group dieted for 16 weeks without a pause.
The intermittent group dieted in eight 2-week blocks, with seven 2-week blocks at energy balance between them. Their program took 30 weeks.

The results cover the 36 men who completed the program as designed (19 continuous, 17 intermittent):

Weight loss: 14.1 kg with breaks and 9.1 kg without (P<0.001).
Fat loss: 12.3 kg with breaks and 8.0 kg without (P<0.01).
Fat-free mass loss: similar, at 1.8 kg and 1.2 kg (P=0.4).
Weight change in the break blocks: minimal, at 0.0 kg on average.

The fall in resting energy expenditure did not differ between groups in absolute terms (502 and 624 kJ per day, P=0.5). After adjustment for changes in body composition, the fall was smaller with breaks: 360 kJ per day against 749 kJ per day (P<0.05). That is about 86 against 179 kcal per day.

Two limits apply. The trial studied only men with obesity. The main result also leaves out the 15 randomized men who did not complete the program as designed.

Do diet breaks help people who lift weights?

Two randomized trials say no for fat loss.

The ICECAP trial randomized 61 resistance-trained adults (32 women). One group did 12 weeks of continuous moderate dieting. The other did four 3-week diet blocks with three 1-week breaks at energy balance, for 15 weeks in total. The analysis included all randomized participants.

Fat mass at the end was 15.3 kg with breaks and 18.0 kg without, and the difference was not significant (P=0.321). Fat-free mass was 56.7 kg in both groups. The groups did not differ in resting energy expenditure, leptin, strength, or muscle endurance.

The groups did differ in appetite. The break group reported lower hunger (P=0.002) and lower desire to eat (P=0.014), and greater satisfaction (P=0.016).

A second trial randomized 38 resistance-trained women. One group cut energy intake by 25% for six weeks. The other took one week at energy balance after every two weeks of the same cut, for eight weeks in total. All were told to eat 1.8 g of protein per kilogram of body weight per day, and all did three supervised lifting sessions each week.

Body composition and resting metabolic rate did not differ between groups. One eating behavior score did. Disinhibition, a measure of loss of control over eating, rose in the continuous group (4.91 to 6.17) and fell in the break group (6.80 to 6.05).

Do refeed days protect muscle or metabolism?

One small trial suggests they may. Campbell and colleagues randomized 27 resistance-trained men and women to a diet of about 25% calorie restriction for seven weeks. All trained with weights four days a week. The refeed group (13 people) ate more carbohydrate on two consecutive days each week. The continuous group (14 people) held the same restriction every day.

Fat loss: 2.8 kg with refeeds and 2.3 kg without, with no difference between groups.
Fat-free mass loss: 0.4 kg with refeeds and 1.3 kg without.
Resting metabolic rate: fell by 38 kcal with refeeds and 78 kcal without.

The authors concluded that refeeds preserved fat-free mass and resting metabolic rate. The trial does not show more fat loss. It is also small and short, and the groups started at different body weights (76.4 kg and 83.1 kg). Extra carbohydrate can also raise stored glycogen and water, which count as fat-free mass. The trial also measured dry fat-free mass, and the loss was 0.2 kg with refeeds and 1.9 kg without.

Protein intake and resistance training are the main tools for muscle retention. See our guide to preserving muscle in a calorie deficit.

Why do the trial results conflict?

A systematic review and meta-analysis in Nutrition Reviews pooled 12 randomized trials with 881 participants. Body mass, fat mass, body fat percentage, and waist circumference improved with both methods, with no significant group differences. Resting metabolic rate fell significantly with continuous dieting only, and the fall was significantly smaller with breaks.

Three differences between the trials explain much of the conflict:

Who was studied. MATADOR enrolled men with obesity. ICECAP and the two Florida trials enrolled people who lift weights. In the meta-analysis, the effect on resting metabolic rate was greater in people with overweight or obesity than in resistance-trained people.
Trial length. MATADOR used 16 weeks of dieting. The trials in lifters used 6 to 12 weeks. A shorter diet may give adaptation less time to build.
Analysis and control. MATADOR reported the men who completed the program as designed. ICECAP analyzed all randomized participants.

What happens in the off weeks matters too. A one-year Australian trial randomized 332 adults with overweight or obesity. One group alternated a week of dieting with a week of their habitual diet. Among the 146 people who completed the year, weight loss was 6.6 kg with continuous dieting and 5.1 kg with week-on, week-off dieting. The difference was not significant (P=0.2).

Who might reasonably use a diet break?

The evidence supports a break as a tool for comfort, not for faster fat loss. A break is a reasonable choice in these cases:

Hunger makes the diet hard to sustain. ICECAP found lower hunger and desire to eat with breaks.
You have a long diet ahead. The one trial with a fat loss benefit had the longest dieting phase. Our article on how long you can stay in a calorie deficit covers the signs that a deficit has run too long.
You want a pause for travel or holidays. In MATADOR, weight held steady in the break blocks. The authors of the trial in women wrote that breaks can be used without fear of fat regain.

A break has two costs. The diet takes longer: 30 weeks against 16 in MATADOR, and 15 against 12 in ICECAP. A break also needs an accurate maintenance target, because eating above it adds fat back.

These trials did not include people who take weight loss medicines. GLP-1 medicines change appetite directly, so the hunger findings may not apply. glp1.md covers how those medicines work.

The bottom line

Diet breaks and refeed days do not reliably increase fat loss. One trial in men with obesity found a clear benefit over 16 weeks of dieting. Trials in people who lift weights found none. The pooled evidence shows equal fat loss and a smaller fall in resting metabolic rate with breaks. Breaks can lower hunger, and they do not appear to cause fat regain when calories stay at maintenance. Use one if it helps you continue. Do not expect it to speed up the result.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Talk with your doctor or a registered dietitian before you start or change a weight loss diet, especially if you have diabetes or a history of disordered eating.