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Gained 1kg On The Scales Overnight?

Have you ever stepped on the scales the morning after a big dinner, only to freak out after noticing a 1kg increase?

You might be thinking that your food choices lead to an overnight increase in body fat… but I’m here to tell you that’s most likely not the case!

1 kilojule of body fat is made up of approximately 7,700 calories (that’s equivalent to around 14 Big Macs) making it almost impossible to unintentionally gain 1kg of body fat overnight.

Gaining weight, or more specifically gaining body fat, is an accumulative process that occurs by consuming an excess amount of energy over time.

So… why the increase on the scale then?

Here are some of the reasons you’ve seen a shift in the number on the scale that isn’t due to an increase in body fat…

Eating a higher volume or amount of food

Eating more food volume than usual will result in an increase in total body weight due to the weight of additional food in the digestive tract

Eating a carbohydrate-rich meal

Now, this is not because ‘carbs make you fat’ ! This is because each gram of glycogen (which is what carbohydrates are stored as in the body) is housed with approximately 3g of water. So a higher carbohydrate meal will result in an increase in weight due to the additional water that is stored alongside the glycogen

Salt and sodium intake

Salt and sodium help us us onto water, so consuming foods high in these will result in increased water retention, once again pushing up your total body weight on the scale

The difference between weighing yourself before and after the bathroom

No explanation is needed here!

Menstrual cycle and hormonal changes

Fluctuating hormones across our menstrual cycle can again affect water retention and therefore weight. We are most likely to see alterations here in the week leading up to and the first few days of your period


Rises in cortisol can also impact water retention and thus, weight. This is because levels of cortisol, our stress hormone directly correlate with antidiuretic hormone levels, which control the amount of water inside your body by communicating with your kidneys


Exercise, specifically higher intensity training and heavy lifting creates microtears in the muscle fibres which can also impact water retention, leading to acute water weight changes

What you’ll notice is that these factors are all things that are likely to impact us in some capacity on a regular basis. So for this reason, it is better to work off a weekly average (if you've made the decision to weigh yourself as this is not essential or suitable for everyone) when it comes to monitoring our total body weight as this is a more reliable indicator of the trend of body fat fluctuations.


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