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Why overnight weight gain is simply impossible

Overnight weight gain Its impossible.


You cannot gain fat overnight. You can however see fluctuations in water weight day to day, this is completely normal.

Those who use the scales as a metric of success, firstly I’d recommend looking at other tools alongside this, but secondly will have a better time understanding how and why the scales do and will fluctuate.

Water weight shifts are normal & happen daily, the human body is made of around 65% water, therefore you can appreciate number of factors can shift in this amount when looking at your pull to gravity, ie your scale weight. Its extremely rare to see your scale weight remain the same each day, near on impossible.

Research where individuals were overfed suggest that the participants needed to be fed by almost 40-70% above their maintenance calories (the energy required to meet current daily functions at the current weight) in order to see a significant gain in weight, this overfeeding was also needed for more than 3 weeks. Not only that, of this gain, the research indicates that although the majority was fat mass, there was also gains in fat free mass like body water. So weighing yourself after a slightly higher day or a takeaway where you feel you over ate will not cause you to gain fat, just a shift in water weight.

Many take the number on the scales too literally & hold their whole health accountable to this, its damaging and can halt progress for many increasing negative thoughts and behaviours.

There are so many things that can cause shift in water weight;

Menstrual Cycle

Weighing at different times of the day & using different scales

Eating your last meal close to bed time

Having a larger meal as the last meal of the day

Sleep deprivation

Stress levels

Intense training session



If using the scales as a form of metric, take data over a period of time and assess, fat loss and fat gain takes time, patience and consistency.

Check in with recent behaviours before you step on the scales; Have you slept well? Have you eaten well? How is stress? Where are you in your menstrual cycle? How has training been? Do you feel good? Checking in with yourself before will help not take the number so literally and recognise that things may be impacting the number.


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