Periods and Weight Loss: Why the Scales Can Change During Your Cycle

Have you ever been trying to lose weight, felt like you’ve had a really good week, stepped onto the scales and wondered what on earth has happened?

If your period is due, it might have absolutely nothing to do with how well you’ve been doing.

Periods and weight loss can be a frustrating combination because your weight doesn’t necessarily move neatly downwards just because you’re eating differently or becoming more active. Hormonal changes during your menstrual cycle can affect things such as bloating, water retention, appetite and digestion, all of which can influence what you see on the scales.

I wish I’d understood this better when I was losing weight because I used to put far too much importance on individual weigh-ins. When you’ve spent an entire week hoping to see a loss, stepping on the scales and seeing a maintain or even a gain can feel incredibly disappointing. It’s very easy to immediately start wondering what you’ve done wrong.

Sometimes, though, you haven’t done anything wrong at all.

Your body weight isn’t simply a measurement of body fat. It’s also water, food and drink passing through your digestive system, waste, muscle and everything else that makes up a human body. Add the hormonal changes of a menstrual cycle into the mix and it’s hardly surprising that the number doesn’t behave itself every week.

Do you weigh more during your period?

You might, although not everybody experiences exactly the same pattern.

Bloating and weight gain are recognised symptoms of PMS, which occurs in the weeks before a period. The NHS also lists changes in appetite and food cravings among common PMS symptoms.

For some women, this means the scales go up shortly before their period and then come back down again afterwards. Others might barely notice any difference at all, and your own pattern can even vary from one month to another.

The important thing to understand is that a sudden increase around your period doesn’t automatically mean you’ve gained that amount of body fat.

Short-term changes in body weight are often influenced by fluid retention. Meals, hydration, digestion, bowel movements and hormones can all affect what you weigh on a particular day.

That’s why looking at one number in isolation can be so misleading.

Why can your weight increase before your period?

One of the biggest reasons is water.

Hormone levels change throughout the menstrual cycle, and those changes can influence how much fluid your body retains. Premenstrual water retention and bloating are common, and hormonal changes are thought to play an important role.

You might notice this in ways other than the scales too. Your rings may feel tighter, your stomach might feel more bloated or your clothes may suddenly feel slightly different even though they fitted perfectly well a few days earlier.

This is one of those occasions where knowing what’s happening can save you from making unnecessary changes to your diet. If your weight suddenly increases around the same point in your cycle every month, immediately deciding you need to eat much less because your “diet has stopped working” isn’t necessarily helpful.

Give your body a little time and look at what happens over the rest of your cycle.

Of course, periods aren’t the only reason your weight can suddenly change. Saltier meals, eating more carbohydrates than usual and even starting a new exercise routine can all affect how much water your body holds onto. I’ve explained more about this in my article on water weight vs fat loss, including why a sudden gain doesn’t necessarily mean you’ve put on body fat.

How much weight can you gain during your period?

I’d be wary of becoming too fixated on an exact number here because everybody is different. You’ll see figures online saying you should gain a particular number of pounds before your period, but bodies aren’t that predictable. Some women notice a significant difference on the scales, while others barely notice anything.

Cleveland Clinic notes that a temporary change of around 2–5lb can occur around a period, but that’s a general estimate rather than a target or rule your body is expected to follow.

I’d be much more interested in learning your own normal pattern.

If you track your weight and menstrual cycle over several months, you may notice that you tend to be heavier at a particular point and that it disappears again afterwards. Once you recognise that pattern, it becomes much easier not to panic every month.

If you’re experiencing a much larger or persistent unexplained change in weight, particularly alongside other symptoms, that’s different and worth discussing with your GP.

Does period weight disappear afterwards?

If an increase is largely caused by temporary water retention, you may find that your weight settles again as your period starts or finishes. This can create another problem when you’re trying to lose weight, though.

You can end up thinking you’ve suddenly had an amazing week because you’ve lost several pounds, when some of that change is simply the extra fluid disappearing.

I remember how much individual weigh-ins could affect my mood when I was losing weight. A big loss felt fantastic, and a disappointing result could make me question everything I’d done. Looking back, I gave those numbers far more power than they deserved.

This is why I now think trends are far more useful than isolated weigh-ins. Your weight over several weeks tells you considerably more than what happened between one Tuesday morning and the next.

Why Does My Weight Fluctuate?

Can you still lose fat during your period?

Yes. Having a period doesn’t somehow switch off fat loss. The confusing part is that fat loss and scale weight aren’t exactly the same thing.

If your body is temporarily holding additional fluid, that can hide other changes happening underneath. You could theoretically be making progress towards your weight-loss goal while seeing no change — or even an increase — on the scales.

Imagine you’ve lost some body fat but you’re temporarily carrying more water. The scales can only show you the combined result. They don’t pop up with a helpful little message saying: “Don’t worry, Jen, 2lb of this is water.” It would be considerably easier if they did!

This is why I’d avoid making dramatic changes to what you’re doing purely because of one period-related weigh-in.

Why am I hungrier before my period?

If you feel as though you could eat the entire contents of the kitchen before your period, you’re certainly not the only one.

Changes in appetite and food cravings are recognised PMS symptoms.

That doesn’t necessarily mean everyone suddenly needs a particular number of extra calories, nor does it mean cravings are something you need to “beat”. It simply means appetite can genuinely feel different at different points in your cycle.

I think acknowledging that is much more useful than pretending hunger is always a lack of willpower.

If you know you tend to feel hungrier before your period, you can plan around it rather than spending several days trying desperately not to eat and then feeling guilty when you inevitably do.

Making meals satisfying can help. Include foods you actually enjoy alongside sources of protein and fibre, rather than trying to survive on tiny “diet” portions because you’re worried about the scales.

Why Am I Always Hungry?

What about period cravings?

Chocolate always seems to get dragged into this conversation, doesn’t it?

Cravings can be part of PMS, but I don’t think the solution is necessarily to find seventeen ways of tricking yourself into believing a yoghurt tastes exactly like a Dairy Milk. Sometimes you want chocolate because you want chocolate.

Where I think things can become difficult is when you’re following very rigid food rules. If you’ve decided certain foods are “bad”, wanting them more strongly can turn into an enormous battle with yourself. You resist them, think about them constantly, eventually eat them and then feel as though you’ve ruined everything.

I’ve become much less convinced by that approach to food.

If you fancy something, you can include it without deciding the entire day has gone wrong. One chocolate bar doesn’t undo weeks of habits any more than one salad magically creates weight loss.

Why I No Longer Believe in Good and Bad Foods

Your digestion can change around your period too

Another reason the scales can behave differently is digestion.

Hormonal changes across the menstrual cycle can affect bowel habits. Some people experience constipation around parts of their cycle, while others find they go to the toilet more frequently once their period begins.

And yes, this can affect your weight. It’s not glamorous, but neither is pretending poo doesn’t weigh anything.

If you’ve been constipated for a couple of days, the number on the scales may be higher simply because there’s more sitting in your digestive system. Then when things start moving normally again, your weight may suddenly fall.

None of that represents several pounds of body fat appearing and disappearing. It’s simply another reminder that the scales measure everything, not just the thing you’re actually trying to change.

Should you weigh yourself during your period?

This really depends on how weighing affects you.

Some people can step onto the scales, record the number and carry on with their day without giving it another thought. If that’s you, there’s no particular reason you have to stop weighing yourself during your period.

If seeing a gain ruins your mood, makes you want to restrict your food or convinces you that everything you’ve done that week was pointless, I’d question how useful that particular weigh-in is.

You could skip weighing around the point in your cycle when you know you’re usually heavier. Alternatively, you could continue weighing but compare like with like — looking at similar points in consecutive menstrual cycles rather than obsessing over week-to-week changes.

For example, comparing your weight during the week before your period this month with the same stage of your cycle last month may sometimes tell you more than comparing it with a completely different hormonal point seven days earlier.

Most importantly, you don’t have to weigh yourself at all. The scales are a tool. They’re not compulsory.

Don’t try to “make up” for a period-related gain

I don’t think the answer to seeing a temporary period gain is to slash your food intake, exercise excessively or spend the following week desperately trying to force a huge loss.

If the change is caused largely by fluid, your body will regulate that fluid anyway. Trying to compensate can also feed into that horrible diet mentality where every unexpected increase on the scales needs to be punished.

I’ve been there, and it can make weight loss completely dominate your life. A much calmer approach is to carry on with the habits you were already working on and wait to see what the longer-term trend shows.

What if your period affects your motivation?

This is where understanding what’s happening can make a massive difference.

Imagine you’ve eaten in a way you’re happy with, been active, slept reasonably well and done everything you intended to do. Then you step on the scales and you’re 2lb heavier.

If you believe that number means you’ve failed, your motivation can disappear immediately.

You might think, What’s the point? Then perhaps you abandon everything for the weekend because the week has apparently already been ruined.

But if you understand that your period commonly affects your scale weight, that same number has much less emotional power. Instead of deciding your plan isn’t working, you can simply think, Ah, my period is due. I’ll see where I am in another week or two.

Nothing about what you actually did has changed. Only your interpretation of the number has.

How to Stay Motivated When You Have a Small Loss or Maintain

Exercise during your period doesn’t need to be punishment

You can absolutely exercise during your period if you feel up to it, and regular exercise may help some PMS symptoms. The NHS includes regular exercise among things that may help with PMS. But exercise shouldn’t become a way of compensating for cravings or trying to sweat away a disappointing weigh-in.

Some months you might feel completely normal and happily do your usual workout. Other times you may have cramps, feel exhausted or simply prefer something gentler. Walking, stretching or another form of gentle movement still counts. And if what you genuinely need is a rest day, having one isn’t going to destroy your weight-loss progress either.

Gentle Exercise That Really Counts

What if your periods change while you’re losing weight?

There’s another side to the relationship between periods and weight loss that’s worth mentioning.

Significant weight changes, restrictive eating and excessive exercise can affect menstrual cycles. The NHS lists sudden weight loss and exercising too much among possible reasons periods may stop or become irregular.

So if your periods become noticeably irregular or stop altogether while you’re losing weight, don’t simply assume that’s evidence that your diet is working brilliantly.

It’s worth speaking to your GP, particularly if you’ve missed several periods, your periods have changed significantly or you have other symptoms.

Weight loss should be supporting your health, not requiring you to ignore signs that something may be wrong.

Periods can hide progress, but they don’t stop progress

If you’re trying to lose weight and your period is due, seeing the scales increase can be incredibly frustrating. I know how easy it is to attach a huge amount of meaning to one number, particularly when you’ve spent all week hoping for proof that your efforts are working.

But the scales don’t know what you’re trying to measure.

They can’t distinguish between body fat, water retention, food in your digestive system or the fact that you haven’t had a poo for two days. They simply give you the total.

Hormonal changes around your period add another layer of noise to that number.

Once you understand that, a temporary gain becomes much less frightening.

Rather than trying to force the scales back down, carry on with the habits that matter to you. Eat normally, keep hydrated, move in ways you enjoy and give your body time to do what bodies do.

Then look at the bigger picture.

Because if there’s one thing I’ve learned from years of losing weight, regaining weight and thinking far too much about the scales, it’s that one weigh-in tells you remarkably little about how well you’re actually doing.

On the subject of periods

Have you tried reusable sanitary towels or pants yet? I was pleasantly surprised at how much more comfortable they are.

Read my review of some reusable sanitary towels to see if they are for you.

Sources and further reading

• NHS – PMS (premenstrual syndrome) — NHS information about bloating, appetite changes, cravings and other PMS symptoms.
• NHS – Period problems — information about period changes and when to seek medical advice.
• Cleveland Clinic – Why you might gain weight around your period — explanation of temporary weight changes, hormones and water retention.
• Mayo Clinic – Premenstrual water retention — information about fluid retention before a period.

Medical note: This article provides general information and isn’t intended to diagnose menstrual or weight-related problems. Speak to your GP if you experience significant unexplained weight changes, periods that stop or become very irregular, unusually heavy bleeding, severe pain or other symptoms that concern you.

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