We've all been there: you weigh yourself one day and feel super fit and fine, and you do the same the next day and you're three kilos heavier.
What's the deal? Could you maybe not, body? Seriously, is that extra slice of banana bread really to blame?
Don't worry, everyone. There are a few reasonable explanations as to why the scales said you gained weight all of a sudden. PHEW.
"I personally don't recommend my clients weigh themselves daily and, in fact, I ask them to limit it to weekly or even fortnightly -- if at all," nutritionist Pip Reed told The Huffington Post Australia.
Self-worth should not be determined by, or dependent on, a number on a scale.
"Daily weigh-ins can create unnecessary stress, fixation, pressure and even obsession which is not healthy for anyone."
Dietitian Robbie Clark agrees, saying constantly weighing yourself is a bad representation of your true weight, and can warp your sense of self-worth.
"I do not recommend my clients do this. By seeing daily fluctuations of increases and losses, it creates an overwhelming fixation and burden," Clark told HuffPost Australia.
"For some, when they become fixated on the scale number, it becomes a marker of their self-worth. If the scale shows a 'good' (lower) number, they feel better about themselves. However, if the scale shows a 'bad' (higher) number, they may feel like they have failed.
"Their entire mood becomes dependent on a number and an entire day can result in complete negativity and despair if they are not happy with what they see on the scales."
It's no wonder, then, that constantly weighing yourself can lead to unhealthy, obsessive eating and exercise habits.
"Fixating on weight can be detrimental to your emotional wellbeing as you cause yourself unnecessary stress, obsessing about any slight fluctuation that may not be related to how much you are eating and exercising at all," Reed said.
"Scales can create an artificial sense of confidence for some, and they can also crush it, especially if you have set specific weight loss goals," Clark added. "People may start judging food or fitness choices against a number on the scale, which is extremely unhealthy."
"Weighing yourself does not take into account muscle mass and growth, fluid retention, hormones and period cycles for females, and may instead cause someone on a weight loss journey to give up as they are not seeing results on a daily basis," Reed said.
"Not only does your weight change every day, it also changes at different times throughout a single day. So there is no point weighing yourself every day -- and definitely not multiple times a day," Clark said.
Here are six reasonable explanations as to why the scales said you gained (or lost) weight all of a sudden.
1. You have gained muscle mass
If you've been training hard and get on the scales and see you've gained a few kilos (but still feel the same weight, or slimmer), chances are you've gained muscle mass, which is much more dense than fat.
"A kilogram is a kilogram -- both a kilogram of muscle and a kilogram of fat weigh the same. However, one takes up significantly less space," Clark explained.
"Muscle, by design, is denser and more fibrous in nature, as it serves to help support and move your entire body. Since dense muscle tissue takes up less space than fat, it's possible you may weigh the same (or even more) yet appear slimmer than another person with the same weight, a similar height and frame because of the difference in your body composition."
In simple terms: a kilogram of muscle occupies less space than a kilogram of fat, hence the illusion of gaining weight or 'fat'.
"So while you may be losing weight, if you're working out you're inevitably putting muscle on too which is going to help fire up your metabolism, but may not give the whole picture on the scales as you find yourself either weighing the same, or sometimes weighing more, despite having lost fat mass," Reed said.
2. You are a menstruating woman
Ladies, if you've ever felt heavier or bigger at certain times of the month, you're not being paranoid. A woman's weight tends to fluctuate due to changes in hormones.
"Females in particular are prone to daily weight fluctuations due to ovulation and periods, often causing fluid retention and therefore weight gain, and this constant rise and fall on the scales is not indicative of true weight," Reed said.
"Some women put on up to four kilograms in fluid pre-period and even at ovulation too, and in this case you should certainly seek out a healthcare practitioner who specialises in hormone balance to assist with this issue."
3. You've drunk fluid or eaten food
That litre of water you just drank? Yep, that accounts for one kilogram of weight. The same goes for food which you have just eaten.
"The scales may simply fluctuate based on how much fluid you have drunk that day or even how much you have eaten," Reed said.
4. You're wearing heavy clothes
Likewise, if you weighed yourself naked two days ago, and now you're at your friend's house in your winter getup and boots, the scales will reflect this.
"And of course, wearing clothing will cause fluctuations. Weighing yourself first thing in the morning, after you have been to the bathroom and are naked, is going to give you a more accurate reading," Reed said.
"However, again, you should only do this every week or fortnight, so as not to become fixated and disheartened by a few hundred grams here or there of fluctuation.
5. Your diet is high in sodium
If your diet is full of salty foods, this can cause water retention and thus increase the number on those scales.
"The reason these weight fluctuations occur is because of body fluid fluctuations -- your body might retain water from a high sodium consumption, or you may not have gone to the bathroom yet," Clark said.
6. You've just had a sweaty workout session
"On the other end of the scale (pun intended), people who weigh themselves after a big gym session may see that they have lost weight," Clark said.
"This loss, however, is more likely to be fluid loss through sweat rather than direct fat loss."
How often should we really weigh ourselves? According to Clark and Reed, maximum once per week -- and not with the scales you think.
"If losing weight or gaining muscle mass is your goal, weighing in weekly with scales that are going to give a better indication of muscle versus fat versus fluid mass is going to be more helpful (if you have these type of scales available) than a daily weigh in," Reed said.
"It's important to also include measurements to get a more accurate assessment of your body changes. The best weigh in or body assessment you can do for yourself is to use a DEXA Scan (body fat analysis) once a month if you are really interested in your data, until you reach your goals."
Clark also urges everyone to implement consistency when weighing yourself so the reading is accurate.
"Once per week is enough to help you stay accountable without becoming obsessed, which should be at the same time, on the same day of the week, wearing similar clothing (or none at all), and most importantly, on the same scale," Clark said.
"By weighing yourself once per week, you allow time for the scales to actually show weight (fat) loss.
"When talking about reducing body fat, the general population isn't well informed about what is considered to be a safe, healthy and sustainable loss and over what timeframe. A healthy goal is striving for 0.5 kilograms to one kilogram of fat loss per week. The ability to achieve this, however, is determined by many factors."
And in saying all this, it's important not to forget: our weight is just a number and it doesn't define who we are.
"My advice to people is that self-worth should not be determined by, or dependent on, a number on a scale. They should be determining their health by other numbers and factors such as blood pressure, cholesterol, insulin and inflammatory markers," Clark said.
"Regardless of whether you fall into this metabolically healthy category or not, these factors are far more indicative of overall health status than the numbers on the scale, and not to mention potentially lifesaving.
"When you make healthy lifestyle choices, you can see dramatic, long-lasting changes in these particular numbers, which should be motivation in itself to keep pushing on with healthy eating and exercise habits.
"Other markers for better health that people should be looking at are improved energy levels, better sleep, clearer skin, better bowel movements, better sex and feeling happier and healthier."
If you need help in a crisis, call Lifeline on 13 11 14. For further information about eating disorders, contact the Butterfly Foundation on 1800 33 4673 or talk to your GP, local health professional or someone you trust.
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