But Wednesday is the best day of all because that is when weight is least likely to fluctuate so it gives a truer reading and makes is easier to compare one week to the next, it added.
Typically, consumers weigh the most at weekends and then burn if off bit by bit during the week, said the researchers from Finland’s Tempere University of Technology.
How much more they weigh at weekends can depend on whether or not they go out to eat, snack or have a quiet weekend so their actual weight jumps around quite a lot.
As a result, weighing themselves on a weekend can see much bigger gains or losses and present an inaccurate picture of their attempts to lose weight.
But Wednesdays, generally, give a much more typical reading of their genuine weight and makes it easier to compare one week to another, researchers told the journal PLOS One.
For those genuinely trying to slim, going for more than a week without checking the scales WILL see them put on weight, said Finnish lead research Dr Elina Helander.
That is because regularly monitoring helps them stick to a rigid weight loss regime as it reminds them just why they are doing what they doing, she said.
It is a standard method of slimming clubs and weightwatcher-style groups to have a weigh-in every week in front of other members to give slimmers encouragement.
The Finnish team took 40 overweight adults and analysed 2,838 different weight readings over the course of a year.
They found how and when the individuals weighed themselves related directly to how much weight they lost.
Dr Helander said: “The more often you weigh yourself the more weight you lose.”
Those who went more than a week without weighing themselves put on weight, she added and of those who weighed themselves once a week were most successful if they did it on a Wednesday.
Analysing the results, US expert Dr Brian Wansink of the Food and Brand Lab of Cornell University in New York State, told PLOS One: “The bottom line is: If you want to lose weight, it’s best to weigh yourself every day.
“But if you weigh yourself only once a week, do it on Wednesday because that will give you the most accurate reading.”