Did your body fat really just increase in the last two days?

By 1st August 2019 No Comments

This is Fitness

Did your body fat really just increase in the last two days?

Our Inbody device provides a comprehensive and non-invasive means to accurately measure body composition. The Inbody device uses Bioelectrical Impedance Analysis as a way to measure body composition, namely through muscle mass and body fat. Bioelectrical Impedance Analysis technology measures ‘total body water’ by reading the impedance (resistance) of low level currents through the body.

It’s important to understand the context around the readings to allow a clearer analysis of individual results; temporary changes in your body can produce temporary changes in body composition results.


Weighing in before or after exercise does infact have an impact results, namely body fat readings. During exercise water is concentrated to the exercised area to supply nutrients and remove waste products. After exercise, impedance decreases and so does body fat – i.e. you will look leaner after you train. Body temperature naturally increases during exercise which too reduces impedance and decreases body fat %.

Body temperature:

Where the body is exposed to warmer temperatures, skin temperature increases and body fat % decreases. Generally lower body temperature means an increase in impedance, which means lower fat free mass (ie. less muscle, more fat). A study showed that sauna exposure increased body temperature and caused a 1.7 – 3.2% reduction in body fat. After being in an icy room, body temperature decreased and body fat increased by 1.3 – 4.2%. And while body temperature from the cold exposure returned to normal after 30 minutes, body fat % did not return to a stable state even an hour after cold exposure.


Eating decreases impedance through the ingestion and digestion of food. It’s been observed in recent studies that where meals are eaten frequently over the course of the day impedance is infact impacted and body fat can fluctuate by up to 8.8% for females and 9.9% males.


Clothing, and faeces/urine do not affect impedance (resistance), and are considered as fat mass as electricity does not flow through them. As such, not going to the toilet will provide a much different reading than after going to the toilet. Body fat therefore decreases immediately after going to the toilet (reduced body weight used as the amount of fat mass). So consider this too as a factor.

Menstruation: (Ladies it’s a biggie):

Ladies results will observe a noticeably larger variability than men due to the menstrual cycle. Weight is increased in the luteal phase (day 14 onwards in cycle) due to accumulation of total body water (increase in progesterone) which results in a decrease in body fat %. However, diet at this time (increased sweet/salty food cravings) could cause an accumulation of fat mass, thus increasing body fat. Weight and body fat are proven to change quite considerably during the luteal and menstrual phase and although these changes are largely subject to individuality we’d strongly recommend ladies avoiding the scales during the luteal/menstrual phase and taking advantage of readings during the follicular phase (day 1-14) of the cycle where possible.


Sleep deprivation plays an key role in body composition and understanding its importance and its place is also important in analysing your results. The Ghrelin, typically increased as a result of a lack of sleep, is responsible for reduced energy expenditure and increased appetite.

As a result, poor quality, lack of and inconsistent sleep patterns will impact your body’s ability to effectively stimulate fat loss. A study conducted by the University of Chicago Medical Centre in 2010 titled ‘Sleep Loss, Limits Fat Loss’ concluded when dieters got a full nights sleep they lost the same amount of weight as when they slept less. The findings however mre importantly showed that where these dieters got adequate sleep, more than half of the weight they lost was infact from fat mass.


Weight is infact a large contributor in the analysis of total body water. For the most accurate results it’s better to remove clothing and step on the scales fasted and once you’ve been to the toilet. (Ladies, we’d recommend during the follicular phase of your cycle too). In reality, it’s not always possible to step on the scales in the ideal environment so it’s important to observe your behaviours before analysing any readings.

If in a circumstance where your results haven’t reflected that of your expectations or infact taken a turn for the worse, it’s important to understand that it doesn’t automatically mean your body fat has actually increased in such a short space of time (and equally you probably haven’t gained 3kg of muscle in a week either).

The biggest consideration is the consistency of your readings (time of day/when you’ve eaten/time of the month). When analysing results we’re looking for overall patterns and trends rather than single readings in isolation. A regular routine will provide a much more accurate picture of what your readings actually look like.

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