min read

Weight fluctuations: what are they and what causes them?

Daily weight changes are normal, in fact, weight can fluctuate up to 3kg a day. In this article we explore why the scales can change so much day to day.

Written by
Sanchia Parker
Accredited Practising Dietitian and Nutritionist
Reviewed by

The average person’s weight will fluctuate between 1-2kg over the course of a day, making weight fluctuations perfectly normal. 

So if you notice your weight has changed by 2kg overnight, it doesn’t necessarily mean you have gained 2kg of fat. There are many things that affect weight in the short term and cause the scale to go up and down. 

So if you notice the scales fluctuating every day and you are not sure why, take a look at some of the common influencing factors on weight. 

1. Hydration

If you're drinking more water than normal you might notice weight fluctuations because water has weight. On the other hand when a person does not drink enough water, their body holds on to water to prevent dehydration. 

So fluid balance plays a large part in weight fluctuations, and it’s perfectly normal for our body to constantly be adjusting how much fluid we have in our system which can affect the scales.

2. Bowel movements

If you're constipated, you may notice your weight readings stay the same or increase. Stools can weigh between 100-450g so if you're not going regularly this weight will sit in your bowels.

3. Menstrual cycle

Hormone levels fluctuate during the menstrual cycle. The hormonal changes can lead to an increased appetite and fluid retention and bloating. This can lead to perceived or actual weight gain during a period.

4. What you eat

When you last ate and the volume of your meal can affect the number on the scale. Your body needs time to digest food, so if the meal is still sitting in your digestive system, it will add to your overall weight.

5. Medication

Certain medications can cause weight fluctuations due to increased water retention, constipation or even increased appetite.

6. Salt

Foods high in salt can cause your body to retain more water. Some salt in our body is important as it helps transport nutrients around the body, balance water content in the body and regulate blood pressure. However, excessive salt intake can lead to water retention. Your body retains more water to balance the extra salt in the bloodstream. Until the salt is excreted from the body the excess water retention can cause temporary weight gain.

7. Alcohol consumption.

Alcohol is a diuretic which means it causes the body to release water. This can cause dehydration, which can cause water retention, leading to a temporary increase on the scale.


Remember, weight fluctuations are completely normal, so try not to worry too much if you see the scales jump up, as it could be due to a number of factors. 

If you find daily weigh-ins demoralising, you could try other ways to measure your progress instead such as taking body measurements, taking progress photos or using your favourite pair of jeans to check how it fits. 

If you’re looking for a different approach to weight loss, Rosemary Health can help. We have doctor guided weight loss programs that consider your lifestyle, goals and your approach to food and wellbeing.

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Lose 10% weight, feel better
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Lose 10% weight, feel better
Medical weight loss that works.
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Lose 10% weight, feel better
Medical weight loss that works.
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