Understanding Fluctuations in Scale Weight

We’ve all done it. You get on the scales one morning, only to freak out and try to frantically figure out how we gained 1kg in 24hrs.

Self-weighing is not for everyone and the great thing is, you don’t have to do it in order to reach your goals. 

When it comes to weight, there are a number of reasons why it will fluctuate acutely ie. overnight.

These are:

  • You Haven’t Been To The Loo Yet! - Always weigh yourself first thing in the morning, before eating or drinking, after going to the loo, and for consistency, in the same place on the floor to mitigate the chances of errors.
  • Food Volume - You may have eaten a larger quantity of food. This is not necessarily more calories, but it may be that you had higher food volume through increased vegetable intake etc. This leads to greater digestive weight in your system.
  • Eating Times - Maybe you ate later than normal last night? This also leads to greater digestive weight in your system.
  • Higher Intake of Carbohydrates - When our intake of carbohydrates is increased, we tend to hold more water. This is because 1g of carbohydrates is stored in the body with 3g of water. Therefore, having increased carbs one day could lead to you holding more water (water weight) and therefore show as a fluctuation when you jump on the scale.
  • Higher Salt Intake - Similarly to carbohydrates, an increase in salt intake will lead to high water retention, commonly understood as ‘water weight’.
  • Menstrual Cycle - What Stage Of Your Menstrual Cycle You Are At. Eg. Menstrual weight, water retention the week before your period and the week of.

A little bit of science to put your mind at ease

1lb of fat represents around 3500kcals, while 1kg of fat represents around 7700kcals. Therefore, in order to gain 1lb of fat in one day, you would have to consume around 3500kcals MORE than your maintenance calories.

Eg. If a female, whose maintenance calories are 2000kcals, wanted to gain 1lb of fat in one day. She would have to consume around 5500kcals in order to do so. If she wanted to gain 1kg in fat overnight, she would have to consume around 9700kcals in one day.

Of course, this is a slight simplification but hopefully, it conveys the point… if you have been eating ‘normally’ or in line with your goals, waking up 1kg heavier overnight will RARELY represent any real increase in adipose tissue (fat mass) and is far more likely to be a fluctuation caused by one of the above.

So what should I do if I want to keep tracking my weight?

  • Be honest with yourself! - Are the fluctuations normal physical responses or has something changed in your habits, intake or activity?
  • Trust the process - Fluctuations will happen but you will get there! Ride them out and don’t let them derail you.
  • Look at a weekly average rather than a day-to-day figure.
    The important thing is where your weight is moving on average and whether or not that is in line with your current goals.
    Take an average over 7 days, each week, to understand the general direction your weight is moving and if the fluctuations represent something you need to consider more deeply or not.
  • Use other methods of measuring your progress!
    There is nothing wrong with measuring weight, as long as you find you have a healthy relationship with the number on the scales. However, introducing other measures of progress can be helpful for mitigating any worry about acute fluctuations in weight.
    Head to the Tracking Your Progress section to read more.

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