Relationship Between the time of day and weight, inflammation or water (Among other factors) When to weigh yourself?
The measurements obtained by kinanthropometry and bioimpedance are very common methods to assess progress in training. It is important to note that these measurements can be modified by various factors, a fact that reduces their reproducibility and accuracy. Including some important ones are:
- Hydration status of the individual.
- Body temperature and environment, food intake.
- Circadian rhythm
- Even the measurement technique itself
Among them, sure we’ve all heard about the importance of weighing yourself in the morning and fasting. Determinations that have been made in some studies on this aspect have covered various times of day as:
- In the morning, on an empty stomach before breakfast
- At noon, before eating
- In the afternoon
- In the evening, before dinner
In each of these moments, they have been able to take action as height, weight, circumferences, skinfolds, and bioelectrical impedance (the temperature and humidity conditions were standardized). According to some findings, the circumferences and skinfold sum do not vary significantly; however, these factors did show variance to consider:
- Increased Body Mass Index (BMI)
- Weight gain
- Increased total water content (important for bioimpedance, therefore, causes a decrease in fat percentage)
- Lean mass increase (from which water is included).
Undoubtedly, it is one of the most studied and approved throughout history changes. When the individual is standing, their height is reduced steadily throughout the day because of the compression suffered by intervertebral discs, particularly lumbar. So when you take a nap or sleep during the night, some or all high recovers lost during the day.
The average loss is not very significant, it accounts for about 0.8-1.2% of the total height of the individual.
Weight and BMI
Reflected changes in weight are primarily due to changes in body water content, as well as food intake, obviously. Directly related to this and the previous section (height), BMI increases to 3% throughout the day.
We recall that “BMI = Weight / (Height * Height)” [kg / m2], so for an individual with normal BMI (18-25), this change would mean a maximum change of 0.54 to 0.75. Even for an athlete is not an overly valid indicator (better IFTF, for example), it can be that in untrained subjects and are within the limits, results in an erroneous assessment of thinness or overweight by the time of day this measure is considered.
% Fatty bioimpedance
Reducing the impedance (mean 06.05%) is attributed to the redistribution of body fluids. When the bioelectrical impedance is used, the % fat is estimated by the resistance by different body tissues and fluids to the electric current generated by the machine.
When we are standing, the water moves from the intracellular and vascular compartment to the extracellular, especially in the extremities.
Conclusions: when taking measurements and weigh ourselves?
Circadian changes should be considered when making and evaluate the measures. That is why we must always be done in the same way, but does not have to be under fasting conditions and in the morning. If this time is often used is that the height is the maximum of the day, the weight is the minimum and liquids are intracellular compartments: the impedance (% fat) is the maximum possible.
However, specialists kinanthropometry training and assessment, they do indicate that in elite athletes, comparative measurements must be performed on an empty stomach.
Also, failure to have found significant changes in body circumferences and skinfold indicates that these methods are most useful for estimating the percentage of fat at any time of the day (more impedance).