In a calorie deficit, and particularly when you lose body fat, your hormones like leptin, thyroid, grehlin, and nervous system hormones adjust to slow fat loss and prime your body to re-gain fat when eating occurs again (see Metabolic Adjustments), which often includes increased hunger. Your body is also breaking down stored energy for fuel (catabolism) which prevents muscle gain.

It's normal for your metabolism to adjust to your new lower weight. However your body can also adapt even further, essentially fighting back to avoid losing body fat. These adaptations can slow or stop weight loss.

One hormonal imbalance that can cause problems is cortisol. Dieting and weight loss by itself is a type of physical "stress", and that stress increases cortisol levels. Stress and cortisol also rise if you are exercising too much (typically lots of cardio/aerobic) while trying to diet and lose weight. Your body may still be losing fat -- even if it is slower -- but it is masked by the water weight.

The bottom line:

One way or another, when you are restricting calories and/or losing weight, your body MAY decide to rebel and make weight loss harder.
This causes weight loss plateaus and metabolic-related breakdowns that cause excess hunger, fatigue, low energy, low strength, etc

Who Does This Affect?

People with a lot of weight to lose have the least trouble and least need for breaks. The leaner you become, the more biological resistance you are likely to encounter. The body fights extreme lower levels of fat just like you were starving. Getting rid of that last stubborn fat can be difficult. On the other hand, if you are obese or very overweight, you can typically diet and lose weight for a lot longer without running into problems. As usual, this effect is genetic and varies by individual.

In general, the greater the calorie restriction on a diet, the more likely you'll need metabolic breaks as part of your overall plan. If you're on a slower/gradual weight loss plan then breaks may not be needed.

Solution: Eat More!

The solution is simple: you need to eat more! Take a break from calorie restriction and bump up calories.

When you increase calories to maintenance levels or higher ("overfeeding"), those negative effects start to reverse. Hormones return to normal levels and send a signal to your hypothalamus that you are eating enough. Metabolism increases. Muscle building can occur again (an anabolic state).

This process may be called "normalizing" or "up-regulating" your metabolism.

When you return to your diet (calorie deficit) again, you should start losing weight. And you should feel better, too.

Another Solution: Less Exercise

In some cases you need to exercise less during a diet -- especially if you have been doing a lot of aerobic (cardio). Eating enough to fuel your workouts is required. If you are severely restricting calories (e.g., a very-low-calorie diet) the most you should do is easy walking or a short, moderate resistance exercise routine.

Requirements for Normalization

Standard requirements for resetting metabolism:

Increase calories to weight maintenance level or higher (you cannot be in a calorie deficit)
Increase carbohydrate intake so you're consuming at least 100 grams per day

Really? Increase carbs? Yes, but it only applies if you've been following a low-carb weight loss plan (but not ketogenic: see note below). Carbohydrates play a particularly important role in normalizing or "up-regulating" changes to hormones and metabolism in response to weight loss. Overeating carbs normalizes most hormones that are involved in bodyweight regulation. Consuming fats and proteins doesn't have the same effect. For those reasons, protein and fat are typically kept at the same level.

Warning: On high carb days, you should eat low fat -- try to keep fat below 50 grams. Otherwise you'll end up storing a bunch of fat. (Remember when you consume a calorie surplus, it's not carbs that turn to fat -- it's the fat).

Ketogenic diet: If you're dedicated to following a true keto diet, it's possible for the body to adapt to a complete fat burning metabolism such that a carb boost may not be needed.

Protein: Protein levels can (should) remain the same, or at least you should not worry about it. You're adjusting fat and carbs.

How long does normalization take?

Depending on the diet, the level of fat, the strategy, and the person -- you could be 80 - 100% of normal within a few days. Some experts surmise that a full system reset may take at least 3 - 4 days, simply because that's how long it typically takes for everything to down-regulate in the first place. Other experts suggest 2 weeks (a common diet break period). For some more extreme situations, it may take a few months to be back at 100%.

You'll typically know where you stand by how you feel -- and because you will start losing weight after you go back to a calorie deficit (your weight loss diet). Sometimes you may even lose weight during the time you are increasing calories and eating more!

Methods and Protocols

There are a number of ways to take a Metabolic Break. Refer back to the introduction or other pages.

A Sudden Weight Increase is Normal

When you increase your carb intake -- especially if you have been previously eating low-carb -- your weight will increase due to water weight from glycogen storage (see Water Weight Fluctuations). Your muscles and liver can store 3 - 4 pounds or so of weight as glycogen. This is not fat gain. If you are still "eating healthy" you won't gain any significant fat.

Will I Regain Fat?

This is a natural concern. However, there isn't much to be worried about as long as you don't let it go for months of uncontrolled eating.

A number of years ago, a study was done to determine what happens when people were removed from a weight loss diet for 2 or 6 weeks. The researchers were surprised to discover that the subjects did not regain very much weight at all in spite of having no specific dietary restrictions during the break -- this was true for both the 2 and 6 week break. Furthermore, they had almost no trouble going right back to the diet.

This diet break concept ("eat more to lose more") has been proven in the real world, too -- many, many people have broken through plateaus using a diet break or even just a short 2-day increase in calories.

Keep in mind: A "break" isn't an all-you-can eat buffet You should treat it more like a maintenance diet that implements easier or lifetime controls mentioned throughout this site (intermittent fasting once a week, eating "properly" during the day with a free meal at night, etc)

It may be helpful to realize that fat gain takes longer than you think. To gain one pound of fat requires 3500 calories. That means over 2 weeks, to gain 3 - 5 lbs of fat means you would have to eat more than 750 to 1250 calories ABOVE your weight-maintenance calories... every day. For example, if your body maintains itself at 2000 calories, then you'd have to be eating 2750 to 3250 calories every day for 14 days to gain 3 - 5 pounds of fat.

So as long as you don't go crazy and are even somewhat moderate in your eating during a break, you don't need to worry about regaining fat (notice we said "fat"... weight is different).

Remember: Weight gain isn't necessarily fat gain (see Weight Loss vs Fat Loss). If you include carbs in your diet break (which is quite likely) you will probably gain some water weight .. unless you were already eating plenty of carbs during your weight loss which isn't likely because most plans restrict carbs either directly or through low calorie levels.

Even if you do gain back some fat (like 1 - 2 pounds), what you lost before the diet break should be much greater. In other words, you will still have a net fat loss over time (over multiple cycles of diet/break/diet/break). Plus, you will have done your metabolism and hormones a big favor -- making your weight loss after the break that much better.

So don't worry about a few pounds of gain ... and get back on the bandwagon!

When To Take a Break?

The leaner you get, the shorter period of time you should diet before breaking. The more fat you carry, the longer you can diet before needing a break. If you are obese you could go for 12 or more weeks without needing a break. If you are overweight, roughly 6 - 12 weeks is a good weight loss period. If you're getting very lean you should only be dieting for around 4 to 6 weeks at the most.

Of course, how you feel is the ultimate factor. If you are starving, losing energy, emotionally tired, etc... then you should consider a break of some kind even if it isn't planned. You could simply increase calories for 1 week, then return to your lower-calorie diet plan.