Things to consider when regularly weighing yourself

Whether it be weight gain or weight loss the scales have arguably been the most common measure of checking progress.

When it comes to fat/weight loss it’s not as simple as jumping on the scales to check progress as this can often give misleading results. Let’s look at a few factors that can affect our daily weight on the scales.

Water levels

For humans to survive and function water is an essential factor.

Body water comprises approximately 45-75% of an individual’s bodyweight (Ref1,2)

Muscle mass is 70-75% water (Ref1,3)

Water in fat tissue can vary between 10-40% (Ref1,3)

Our water levels are affected by diet, daily activity level, age and the environment we live and work in. (Ref1)

Things to consider:

The long and short when water loss exceeds water intake this promotes renal water retention.

Mild dehydration (1-2% of water loss) equates to about 1.5-3lbs of bodyweight loss for a 150lb person. (Ref1)

Bowel Movements

Going to the loo can cause some fluctuations with your scale weight. According to research you can create 125 to nearly 170 grams of stool daily, which is less than half a pound. (Ref 4)

Salt levels

Foods high in salt can cause water to retain in our bodies. The levels vary depending on the individual. (Ref 4) The NHS recommends adults eat no more than 6g of salt per day 2.4g of sodium (1 tea spoon). (Ref 5)

Menstrual Cycle

When speaking to female clients most have fed back that they do suffer with bloating during the menstrual period.

Studies showed that fluid retention was at the highest on the 1st day, the lowest during the mid phase and then an increase over the next days of ovulation. (Ref 4,6)

Alcohol intake

Ever felt lean the morning after a night out boozing? As a result of a night out fuelled by alcohol we wake up dehydrated the next morning meaning less weight on the scales.

Alcohol is a diuretic so it can make us go to the loo more often. (within 20 minutes of consumption leading to fluid losses and potential imbalance). (Ref 4)

On the other side if you smash back some kebab and chips at the end of the night this can increase salt content and guess what….Water retention leading to weight gain on the scales.

Muscle Mass

A kilogram or Muscle weighs the same amount as a kilogram of fat, it just takes up less room in our bodies. If you consistently been weight training and eating well your fat mass may have reduced and lean muscle mass increased therefore little or no effect on the scales weight.

Having your body fat levels tested as well as taking measurements and pictures are good measures to check for muscle growth.

As a side note:

The body generally prefers to build lean mass when in a positive energy balance of calories as it has all of the necessary calories and macronutrients to do so.

However in situations such as, overweight individuals with little exercise experience, these people can achieve muscle growth in a calorie deficit with a supported appropriate levels of protein. (Ref 7)

As you can see a lot of these reasons relate to water levels and there are more that we could go through. My point is not to rely solely on the scales as a measure of progress.

I read and liked that there is no such thing as normal weight (Ref 4). However if you see consistent drops or increases weight then this is a clear sign that your body mass is changing.


  1. The Hydration Equation: Update on Water Balance and Cognitive Performance Shaun K Riebl, MS, RD, PhD Student and Brenda M. Davy, PhD, RD, FACSM, Associate Professor

  2. Jequier E, Constant F. Water as an essential nutrient: the physiological basis of hydration. Eur J Clin Nutr. 2010 Feb;64(2):115–123. [PubMed]

  3. Institute of Medicine of the National Academies. Water. Dietary Reference Intakes for Water, Sodium, Chloride, Potassium and Sulfate. Washington, D.C: National Academy Press; 2005. pp. 73–185.

  4. How Much Weight Fluctuation Is Normal from Day to Day? Find out how bowel movements, food, and menstruation affect your weight By Malia Frey


  6. Fluid Retention over the Menstrual Cycle: 1-Year Data from the Prospective Ovulation Cohort Colin P. White, 1 Christine L. Hitchcock, 2 Yvette M. Vigna, 2 and Jerilynn C. Prior 2

  7. Building Muscle in a Caloric Deficit: Is It Possible? Martijn Bussen

Leave a Reply

Your email address will not be published. Required fields are marked *