What to do when you’ve gained weight on a Monday

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what to do when you gain weight on a Monday

Why you should expect to gain weight on a Monday and why it doesn't mean you've failed on your diet

Every client I have worked with over my 10+ years of coaching has, at some point text me in a worried panic that they’ve gained weight.

I would say that 50% of these calls are on a Monday.

It’s so common that I’ve filmed a video which is at the end of this podcast/article that I now direct them to after having a quick chat.

The fact is that Monday weight gain is a well documented occurrence and unfortunately it can result in people jacking in their diet.  They work hard all week, see the scales go down and then Monday comes and BOOM! It’s back up again.

It’s pretty demoralising.

If you aren’t aware of the possible reasons why this is then you may also fall victim to self doubt and come off your own program of self improvement.   This article and podcast is designed to help you understand the Monday weight gain phenomenon and to embrace it, not be afraid of it.

Is your weight gain actually body fat?

Logic must be used when assessing if weight gain is body fat. 

To gain 1kg of body fat you must first be in a calorie surplus.  If you have eaten more calories than your body needs for energy then it will be stored.

The main stores for energy are the muscles and body fat.

Muscles store glycogen which is carbohydrate that you have eaten. Therefore the more muscle you have the more glycogen you can store and thu more carbohydrate from your food can be put there. This is why I am a big proponent of every person using resistance training (weights) as a staple of their exercise.

If the muscles are full then the body must look at other avenues for disposing of the excess.

This can be through increased NEAT activity (Non Exercise Activity Thermogenesis) which may involve more walking, fidgeting and general activity.

As a last resort the body will look to store the energy for later use as body fat.

Carbohydrates are more easily stored as glycogen and used for NEAT and take more time to convert to fat.  Fat on the other hand can more easily be converted to body fat.   This is one reason I advise most clients to follow a medium carb, low fat diet as if they overeat there are buffers in place to reduce the body fat stored.


Let’s, for argument’s sake, say that all the energy surplus in you day went to body fat.


A kilogram of body fat takes around 8800 calories surplus to make.

That’s ON TOP of your normal daily intake.  So if you are an average person your maintenance may be around 2000-2500 kcals.

If you add on the surplus required to make that kg you’ve gained this would mean you’ve eaten 10,000 kcals in 1 day (if you weighed Sunday and then were heavier Monday).

If you weighed Friday and then weighed Monday that would mean you overate by 4000 calories on Saturday and Sunday.  

Did you?

Well of course it is possible but then not all surplus goes to fat.

Monday's are generally a heavier day on the scales

Let’s look at the patterns for the majority of people. 

Most people are less active on the weekend than in the week.  Unless you work weekends or like to go on long hikes you’ll probably relax a bit more and perhaps eat a bit more.

So it’s very possible you’re in more of a surplus than you may have been if you’d eaten the same in the week.

Food carries weight, many people forget this.  The more food you eat, the more weight you’ll be carrying around in your intestine.  This can take up to 3 days to fully clear. When you get on the scales on Monday morning you’ll still be carrying a bit of Friday’s dinner, the Saturday takeaway and the Sunday lunch.

All this food can contribute to more water being retained in the body through elevation of sodium (salt) and for helping process the food.

You’ll also most likely have a nicely topped up muscle glycogen store from the extra carbs.  Glycogen can hold up to 3 times its weight in water so 100g of glycogen can hold 300g water, this is a total gain of 400g.  An average human can hold anywhere around 400g of glycogen.  Full of water that’s 1.6kg!

You may have gained some fat as well but it will be slower to come on, certainly in a few days you won’t see over 1kg of fat being deposited.

What this means is that your Monday workout will be awesome, so don’t waste it.

Weigh every day not just Monday

One thing to bear in mind is that weight fluctuates over the week.

You may very well be heavier on Monday but I’ve found that measuring the average of weight is much more indicative of progress (or lack of it).

Here are two examples of previous male clients who lost weight consistently over time and you can see that although the trend was downward there were always blips along the way.

Weighing every day will allow you to see these trends and identify where the bottlenecks and problem days are.  Most of all they allow you to understand your body better so you gain new confidence in your decisions.

Progress is measured in averages not individual values

The key takeaway here is that Monday is just one day.  the weight on that day is only a measure of your

  • Bone
  • Muscle
  • Fat
  • Food in your system
  • Water 
  • Blood

Some of these will be in constant flux and it’s important to measure them over time to account for variances.  If you are going to weigh, then weigh every day or not at all.

I have clients that don’t weigh at all and simply monitor their body shape or their fitness levels.

The key here is to understand what it is that you want to achieve.  Then measure those things that help you see if you are making progress.  Weight on it’s own is a poor indicator of overall progress.

Watch the video below or listen to the podcast to learn more

Take the Next Steps to Improve Your Health

Choice of any foods you like. 
Tailored to your calories for fat loss.  

5 minute test with free report to improve your chances of success

Purchase direct from Amazon in paperback or Kindle 

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