The scales can lie! Factors that affect bodyweight

We’ve all done that thing where we are training regularly, eating well and feeling really good until we step on the scales and see we’ve actually put on weight!

It’s a huge blow and it’s at this point most people give up and think they may as well go back to not training and eating what they want if they are going to gain weight anyway!

The thing is your weight on the scales can be affected by absolutely loads of factors and living and dying by whatever they say is a really bad idea as your bodyweight doesn’t always give a true indication of your progress.

Here are some of the factors that can affect the reading on the scales:

Time of the day, week or month

If you weigh yourself first thing in the morning you won’t have eaten anything, if you weigh yourself later in the day the chances are you’ll have had things to eat and drink. Now this will make you weigh more, but most people don’t consider this. The difference is food and weight not body fat.

You’ll also find that on different days of the week you’ll be heavier or lighter. Often people eat more at weekends so on a Monday their weight will be up, but after a few days of eating normally, by Thursday for example it might be back down.

I see this with people I work with that their weight can vary enormously across the week. Pick a good day and you’re over the moon, pick a bad day and you’re heartbroken.

Now the way to get around this is to weigh yourself first thing in the morning after you’ve been to the toilet but before you eat or drink anything. Do this on 2-3 different days throughout the week and take the average across the week to assess your progress.

Another factor is your menstrual cycle; often women gain weight around their time of the month due to water retention. The main thing is to be aware of this so it doesn’t catch you off guard and demotivate you. Just go with it, you know it’ll come down again.

What you eat and when

Eating salty food can also cause water retention and therefore an increase in what you weigh. So if you happen to eat a meal containing more salt you’ll weigh more. This doesn’t mean you’ve got fatter, it’s just water and again it will come down. Just be aware of what you’ve eaten and mindful of how it can affect your weight.

Eating more carbohydrates can have the same affect, and again it’s not that you’ve got fatter, your body is just temporarily holding onto water.

The time of day that you eat will affect what you weigh the next day. If you normally have your dinner earlier in the evening and then one night eat later, the chances are you’ll weigh more the next morning.

Working out

If you’ve trained using weights this causes damage to the muscle tissue which results in inflammation. Your body will repair itself by supplying the muscle with nutrient rich blood to help it heal. This can lead to temporary fluid retention so again your weight may be higher the next day.


An obvious one, and I won’t dwell on this, but if you’re having trouble going to the loo then again your body weight will be higher than normal.

Moving on…

What you’re wearing

This might seem like a ridiculous one to mention but it’s something else people overlook. If you weigh yourself at random times and don’t consider your clothing or footwear then you are making life even harder for yourself. The weight of your clothes and footwear will vary and so will your weight. The easiest solution is just to weigh yourself either naked or if this isn’t appropriate aim to always be wearing the same or similar clothing.


If you are dehydrated then your body will contain less water and therefore be lighter. Equally if you’re well hydrated then you’ll weigh more. Neither mean you’ve gained or lost fat but both will affect the reading on the scales.

Simply try to be consistent with how much you drink (you should be doing this for optimal health anyway), and if you are dehydrated be aware that you’ll weigh less and your weight will go up once you drink more.

This isn’t just affected by how much you drink, if you sweat a lot in your sleep then this will also affect your reading the next morning.

You see lots of people weighing themselves in gyms after workouts, if you’ve sweated more in that workout then your weight will be down, you’ve not just suddenly lost loads of fat. Similarly you may have had more water to drink during your workout. So basically just don’t bother weighing yourself after you’ve trained, it’s pointless!

In summary

As you can see see there’s a whole host of factors that will affect your bodyweight, so hopefully now you realise that being too happy or sad based on the reading is ridiculous.

I’ve lost count of the times over the years where I’ve weighed a client and their weight is up or the same but then I’ve checked their tape measurements and they’ve lost inches!

This is why I advise people to take tape measurements and pictures to monitor progress, and keeping an eye on how your clothes are fitting is a good indicator of progress too.

And more importantly, going back to what I said at the start, if you are training regularly, eating well and feeling really good then what does it matter what the scales say?

So my advice would be to also use other methods to monitor progress and if you are going to be weighing yourself:

    • Do it first thing in the morning after you’ve been to the toilet, before you’ve eaten or drunk anything.
    • If you can’t weigh yourself naked try to wear the same or similar clothes each time.
    • Try to weigh yourself on 2-3 different days across the week and take an average.
    • Be mindful of the impact of hydration, the food you’ve eaten and your time of the month.
    • Look for your bodyweight to be coming down as a general trend but don’t expect it to come down each time.

But please don’t let yourself become obsessive about your weight, there are far too many factors to base your success or failure on the reading on the scales.