Does A Cheat Day Undo A Week at the Gym?

  • Fat gain or loss is determined by how many calories you take in and how many calories you use in a day
  • Water weight can come from increased glycogen, an energy source that is produced primarily from carbohydrates
  • A cheat day every once in a while will not erase weeks and months of hard work

Your hard work is paying off with your diet and workouts, and you keep making progress. The weight loss goal is in reach, and you decide to treat yourself. It might be a snack, a cheat meal, a cheat day, or even a weekend. When Monday comes, you weigh yourself for your weekly weigh-in, and you can’t believe it: you’ve gained 5 pounds.

First, the bad news: no the scale isn’t lying to you, you’ve gained 5 five pounds. Here the good news: it is not 5 pounds of fat.

If it is not fat, what is it? Are cheat days a good idea for your diet and fitness plan?

What are cheat days?

First, a quick overview. What exactly is a cheat day?  “Cheat days”, despite the negative connotation, are planned breaks from your diet plan. Rewarding yourself with scheduled breaks from your diet plan, may help you stick to your diet plan, build better habits, and achieve long-term success. 

What you plan to indulge in on your cheat day depends on the individual’s tastes and appetite, but the key idea is to let loose and enjoy yourself with something that isn’t on your diet plan. 

 Not every diet will allow for “cheat days”. The Paleo diet, for example, eliminates entire food groups and doesn’t allow for any breaks from the diet plan. But no matter what diet plan you are on, incorporate meals that you can look forward to helping make the diet plan sustainable. 

What are the benefits of a cheat day?

Cheat days can be a great tool to help motivate you to stick to your diet plan. Use cheat days to build a positive relationship with food. View your favorite dessert or comfort food as a reward rather than a coping mechanism. 

Something that you should keep in mind is that a cheat day isn’t a license to binge eat. Binge eating on your cheat day may lead to eating-related issues and hurt your ability to self-regulate. 

Contrary to popular belief, binge eating does not boost your metabolism. It may have the opposite effect. Just like your diet, it is best to approach it with a plan and the focus on the long-term.

How often should you have cheat days?

There is no hard and fast rule on how many cheat days you should have. Or even if you decide between a cheat meal or day. Ultimately, it depends on how well you self-regulate and what your goals are

 It’s so easy for your cheat day to become a cheat weekend, and then a cheat week. Before you know it, you are back to your old eating habits. It is important to understand what will help you stay motivated.

 The goal is to develop a sustainable, long-term plan. What you should consider are your body composition goal, and how fast you want to reach them. Think about how the extra calories (if any) from your cheat meals will impact your goal. 

Why does a cheat day cause you to gain weight?


A cheat day causes some large weight increases, but weight because of water, not fat. Depending on what kind of diet you were on, loading up on carbs on a cheat day can increase your weight noticeably.

If you were trying to lose fat, you likely were trying to cut carbohydrates out of your diet. It’s a very popular technique, and diets structured around low carbohydrate and low caloric intake are about as basic a diet as they come. The Mayo Clinic notes that a diet targeting low carbohydrate intake makes up about 60-130 grams of carbs a day. Some popular diets—such as the Atkins Diet—target extremely low levels of carbohydrates, as low as 18 grams a day. This will help you lose weight and some of it. 

But once you increase your consumption of carbs, you may see a subsequent increase in water weight.

How much water weight can you gain from cheat day?

If you’re consuming 60 grams of carbs a day, you’re holding onto approximately 210 grams of water. That’s about half a pound of water.

But if on a cheat day, you decide to eat and drink whatever you want and load up to 300 grams of carbohydrates (the average number of carbs eaten by men, according to the US Department of Agriculture), you would retain around 1kg of water or 2.2 pounds. If you were on a 60 carbs/day diet, you could be a pound and a half heavier already. If you went up to 400 grams of carbs, you could add on 2 ½ pounds of water.

Why do carbs cause you to retain water weight?

The reason your body retains water after you consume carbs involves your body’s favorite energy source: a molecule called glycogen. Glycogen is an energy source that is produced primarily from carbohydrates. Your body loves glycogen because it’s an easily accessible energy source that provides a lot of energy. Glycogen also has an interesting attribute: it bonds well with water. In fact, for every gram of carbohydrate in your body, there are about 3 to 4 molecules of water bonded to it.

But glycogen is far from the only substance or factor that can cause your body to retain extra water. Excess sodium can also cause your body to hold on to the water on top of the water held onto by your glycogen. Once you factor in the effects of food, your hormones, and your unique body composition, it is easy to see why your weight fluctuates so much. 

But once you return to eating a low carb, low-sodium diet, your body should naturally shed the extra water weight you gained.

Can you gain pounds of fat overnight?

You can’t gain a pound of fat in a day, or even 5 pounds in one weekend. Biologically, it would amaze us if you did. You are very much aware of how difficult it is to lose fat quickly, but don’t laugh when I tell you, in theory, it is as “difficult” to gain fat.

Fat gain or loss has a lot to do with your energy/caloric balance–how many calories you take in vs. how many calories you use during the day. If you are using more energy than you take in, your body gets some energy it needs from your fat stores. If you’re taking in more energy–eating beyond your body’s needs–then the opposite happens: you build fat stores. 

A common theory in the health and fitness world is that there are around 3,500 calories stored in a pound of fat. The theory goes that if you reduce your daily caloric intake by 500 every day of the week, in 7 days you’ll lose a pound of fat. Conversely, if you overeat by 500 calories a day, you can gain a pound of fat in a week. 

500 Calories x 7 Days = 3,500 calories/week or 1 lb/ week

 The point is, it TAKES TIME to gain or lose fat. (Of course, it is much easier than you think to overeat 500 calories a day. A large blended coffee-flavored drink once a day will do it.)

 To gain a pound of fat, you would need to add about 500 calories a day on top of your normal diet, every day, for about 7 days. This makes gaining any significant amount of fat from even the craziest, all-out cheat days unlikely. To gain 5 pounds of fat in a day, you’d have to eat about 17,500 calories on top of your daily caloric limit.

If you are curious to see the effects of your cheat day, take a body composition test before and after your cheat day to see the changes to your body water levels.  

Do cheat days ruin your progress?

A cheat day every once in a while will not erase weeks and months of consistent workouts and healthy eating.

Cheat days can help keep you stay motivated long-term if you practice mindful eating. But remember, this doesn’t mean you can get carried away on cheat days. It is important to always stay within reason and it will go a long way to help you develop healthy eating habits that you can sustain. 

Do not stress about any sudden weight gain after a cheat day; it’s not fat but just water weight. Just make sure after you’ve had your fun, you get back on your fitness journey and keep working towards your goals. Changing your body composition and losing weight is a long-term process, but if you do it right, you’ll have long-term results! 

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