Why does my weight fluctuate daily?
If you are currently dieting, this is question-usually out of frustration and bewilderment-you’ve likely asked yourself.
You’ve been spot on with your nutrition. You have your calories dialed in and are not making any MISTAKES with tracking your macros.
...one day the scale is up a pound, the next day it’s down 2.5, the day after it’s down 3/4 of a pound, and the next day it’s up 2.5 lbs.
You are thinking to yourself:
What am I doing wrong?
Do I need to lower my calories?
Am I eating the wrong foods?
Do I need to eat more or less carbs?
Should I cut out processed foods and go all organic?
Is this working or even worth doing?
Let me put an end to your frustration and give you some clarity on this.
In this post, I’m going to go into detail about the 11 factors which answers the question: why does my weight fluctuate daily?
Scale Weight Fluctuations Are Normal & Expected
First of all, understand, scale weight fluctuations-even with perfect nutrition-are perfectly normal and expected. Most people’s scale weight will fluctuate 3-5 lbs. throughout the week.
If you can tell me exactly what you’ll weigh every day for the next 10 days...I’ll give a free year of FITNESS COACHING and throw in an extra $500 on top of it.
And I’ll win that bet :)
I, personally, just came off a 12 WEEK FAT LOSS PHASE where I was 95% compliant to my nutrition plan. I tracked my daily scale weight for 52 straight days during the journey as an experiment and I had scale weight swings to the tune of 5 lbs. in a single week (I need you to keep in mind this was with precision nutrition where all variables were controlled). I was, on average, in a 1000+ daily calorie deficit.
It’s easy to lose sight of the fact that, when you diet, body composition changes-NOT JUST “WEIGHT LOSS”-are what you should be after. This is why it’s important (this is what I do with MY CLIENTS) to have many indicators of progress on your weight loss and fitness journey:
Yes, use the scale (I’ll get into how later)
Measurements at the belly button, widest part of your butt, and the widest part of your thighs
Indicator piece of clothing (pull on the same pair of tight jeans or slacks every 2 weeks and subjectively gauge how they feel)
Your scale weight may stay the same for 2 weeks-or go up-but, you may find you’ve dropped a quarter inch on your hips, or a half inch on your waist...or your indicator jeans may be starting to fall down your hips.
THIS is still body composition progress even though your scale weight may have not moved.
So with that out of the way-and this assumes your nutrition and calories are being consistently controlled (see #11 further down)-let’s get into the multitude of factors which answers the question: “Why does my weight fluctuate daily?"
You Ate A Higher or Lower Percentage of Carbohydrates The Day Before
Even if you have your calories in check, are tracking them, and are in a calorie deficit, if you eat a greater (or lower) percentage of your calories in a single (or multiple days in a row) from carbs, your scale weight will be impacted (up if more carbs and possibly down if less depending on the number of lower carb days).
When we eat carbs, they are stored in the form of glycogen in the muscle and liver. This glycogen is bound by water, so, it would make logical sense if you are storing more carb...you are going to weigh more.
Keep in mind, this is not body fat (unless you’ve been eating in a calorie surplus)...just weight.
This is also the reason people LOVE switching to a lower carbohydrate diet from their “normal” diet as the reverse also holds true: if you burn through all your stored carbohydrate, and don’t replace it, you are going to lose, in many cases, a bunch of water weight. This is a transient, short term effect (but exciting) and really has nothing to do with significant fat loss (although if you are eating in a calorie deficit some of it will be body fat).
You Ate Your Last Meal The Day Before Earlier or Later Than Normal
This is pretty simple to grasp. Even if you didn’t over eat and stuck to your calorie goal for the day, if, for whatever reason, you ate significantly later at night than you normally would, you are going to have more food in your stomach and gastrointestinal tract, and, if you weigh in the next morning...voila...you are gonna weigh more.
The reverse also holds true. Maybe you ate an early dinner and your food was digested, absorbed and “passed” faster than normal. It’s possible your scale weight will take a dip.
You Ate More or Less Salt Than Normal The Day Before
Too much sodium, or salt, can cause immediate water retention. This is because the body needs to keep its sodium-to-water ratio balanced to function properly, so will hold on to water if too much salt is consumed.
So, maybe you went out to your favorite chain Chinese joint the day before you weigh in. You did your due diligence and chose a menu item which fit into your overall calorie structure and you stayed in a calorie deficit for the day.
However, the way the chef prepared your orange chicken was loaded with salt (this is all too common at any restaurant). This will cause water retention, bloating, puffiness...and your scale weight the next day will reflect this temporarily (but sometimes significantly).
Obviously, the reverse also holds true, if you ate very low-sodium foods the day before, it’s possible you’ll have a “water whoosh” and your scale weight will take a dip the next day.
You Weighed In Earlier or Later Than Normal
If you weigh yourself at a different time of the day, under different circumstances, than the day before, well, it only makes sense you are going to get a different (and usually unfavorable) reading on the scale.
If you weigh in earlier than normal, you may still have food in your GI tract and this is going to register as extra “weight” (that’s all it is). Conversely, if you weigh in later in the day than normal, especially after eating or drinking something, well, again, this is going to register as more weight. It has nothing to do with fat gain or loss (unless you have been eating in a calorie surplus).
With this said, it becomes obvious that you should track your weight consistently, at roughly the same time each day, under the same conditions:
First thing in the morning
Before eating or drinking anything
Scale in the same spot on the floor (yes that can have an impact)
I’ll get into more on how to weigh-in in a way which doesn’t drive you nuts later on down in the article.
You Had An Unusually Hard Workout The Day Before
It’s important to understand your scale weight is a combination of muscle, fat, bone, the brain and neural tract, connective tissue, blood, lymph, intestinal gas, urine, and the air that we carry in our lungs.
Immediately after a workout routine, the percentage of mass in each of these categories can shift as much as 15 percent. Intense workouts cause variability on the scale due to factors like hydration status, inflammation from muscle damage repair...even the amount of intestinal by-product or urine and blood volume.
So if you crushed the gym the day before a weigh-in, and you get on the scale the day after, you need to understand the spike up you see has A LOT to do with the factors I just mentioned above and likely has NOTHING to do with laying down actual body fat.
Your “Toilet Status” :)
I hit on this a bit above earlier, but weighing in before or after you use the restroom can obviously have an impact on what the scale registers.
I mean, if you pee out 30 ounces of urine...or poo out 3-4 lbs. of fecal matter...it only stands to reason you are going to have a more favorable weigh in (and again, this is literally just “weight”). On the contrary, if you weigh in before you pee, or you have not gone number 2 in 3 days and are backed up, well, common sense dictates your scale weight is going to either be up or not move downward until you literally pass this along.
Again, as I noted above, it’s important that you weigh-in consistently, under the same conditions and regimen to get a real pulse on what’s going on with your weight. The more variables you can control and hold constant...the better.
First thing in the morning
Before eating or drinking anything
After using the restroom (keeping in mind if you have not pooped in a couple days you may not see a drop even if you’ve been spot on with your diet)
You Weighed In Before/After You Ate or Drank
This should be another “captain obvious” one, but if you weigh in after you take down 16 ounces of water in the morning, or after you eat your egg whites, fruit, and oatmeal, well, there is literally more “matter” in your system and in your body and the scale will reflect that (just like if you got on the scale holding a 2 lb. weight in your hand).
If you drink a pint of water...that’s a lb. of liquid in your system.
If you eat 400 grams of eggs, fruit and oats...that’s roughly a pound of food in your GI tract.
I’ll say it again: weigh in under consistent, repeatable conditions. To this point...BEFORE YOU EAT OR DRINK ANYTHING.
For The Female Readers: You Are In a Different Phase of Your Menstrual Cycle
Guys have it rather easy. They have essentially the same physiology 365 days a year.
Women? Lol. They have a different physiology about every 2 weeks.
Due to the menstual cycle, and how their hormones fluctuate, women have it tough. Hunger, energy, and food cravings change throughout the cycle.
So does scale weight.
It is not uncommon for a woman’s scale weight to fluctuate 7-10 lbs. throughout the course of a cycle. This is true EVEN IF a woman is on point with her nutrition and not eating in a calorie surplus. The bloating, water retention, etc., especially during the luteal phase is very, very real.
So, if you are woman and reading this, you need to consider where you are in your cycle when you weigh in as it 100% is going to impact your scale weight.
Instead of throwing the scale across the bathroom when you are late in your cycle....be logical.
I recommend comparing week 1/month 1 of your cycle to week 1/month 2. Then week 2/month 1 to week 2/month 2, etc. This is going to allow you to get a better pulse on what’s actually going on with your trending weight as compared to getting frustrated that your scale weight week 3 of your cycle is 5 lbs. higher than week 1 during the same month.
You Are Under More/Less Stress
If you are stressed the F out...guess what? Your scale weight is going to reflect it.
Increased stress = increased cortisol (a fight or flight hormone). As cortisol levels rise, it brings with it something cortisol-mediated water retention. You could be spot on with your nutrition, but if your boss is up your ass, your kid just got arrested for an open container, your house is in foreclosure...your scale weight is gong to read higher.
Going off on a tangent, increased stress leads to emotional, mindless eating as a coping mechanism to deal with the stressor(s). So, you have a double whammy: you are already holding water plus you are now also likely over eating.
It should be obvious the opposite holds true: if you are in “mellow yellow” state, you are likely going to have lighter weigh-ins. If your stress level is low-or you are finding positive ways to deal with stress-your cortisol levels will be lower.
You’ll also likely be sleeping better (see below), you’ll feel more positive, you’ll be exercising more, eating better...it’s a cascade.
You Are Getting More/Less Sleep
If there is one thing I could point to which will completely derail your diet, it’s poor sleep. Everyone wants to talk about calories (and they are of HUGE importance), but if you are not getting good sleep, it’s going to be hard to have your calories in line and lose fat.
Lack of sleep is a stressor. As mentioned above, increased stress leads to increased cortisol. Increased cortisol leads to increased water retention. Increased water retention leads to high scale readings. Again, this is independent of you nailing your diet.
What’s more? Well, lack of sleep increases a bad appetite hormone (ghrelin) and decreases a good appetite hormone (leptin). “Ghrelin up/Leptin down” is a recipe for disaster. These hormones are a router between your stomach and brain. If these are out of whack, even those with uber willpower will not be able to over ride this.
Bottom line: you’ll be ravenous and want to eat dry wall.
Conversely, getting great sleep will keep these appetite hormones in check (they will still be a little off if you are eating in a calorie deficit), keep your cortisol levels at bay, and you’ll be much more likely to make better food choices and have your appetite under control.
You Are Flat Out Eating Way More Than You Think You Are
I saved this for last, as, many times, your fluctuating scale weight can simply be blamed on eating too much. Too many calories coming in vs. going out.
Many times, people THINK they are eating in a calorie deficit, or My Fitness Pal told them they were, but, upon closer inspection...they are not.
People do a horrible job of estimating their calorie intake (which is why precise tracking and weighing and measuring food is, in my opinion, essential). Research has shown people can be off by as much as 70%.
THINK you are eating 1400 calories? It’s likely closer to 2000-2500.
Do not fool yourself into necessarily thinking your fluctuating scale weight is due to the other 10 factors I outlined earlier. Stuff like water retention is transient and short term. If your scale weight average (more on that below) is not trending downward over several weeks or a month, it’s not due to being constipated, getting poor sleep, or eating your last meal later the night before a weigh in.
Before you talk yourself into “it’s just water retention”, I’d do a serious audit of your nutrition intake to see if you are, in fact, REALLY eating the number of calories you think you are.
This means weighing, measuring (see the macro tracking mistakes article I linked to towards the beginning of this article) and accounting for EVERYTHING-food, drink, condiments, vegetables)-you are consuming for at least 30 days (and preferably you should be doing this 80-90% of the time if you want serious results).
No eyeballing. No assuming. No guesstimating. Precision tracking...what gets measured gets managed.
If, after doing this, your average scale weight is still not trending down, you likely need an adjustment either in terms of the number of calories you are consuming, the macronutrient ratio of your diet, or the amount of activity you are doing.
How To Use The Scale in a Healthy & Accurate Way To Gauge Your Progress
I’ll wrap up this article on “why does my weight fluctuate daily?” by weighing in (pun intended) on the scale.
I’m a big advocate of weighing in daily (I said this a couple times above), first thing in the morning, before you eat or drink anything, nude. If you can control some of the variables, you’ll have a much better relationship with the scale.
What’s more, the weekly weigh in is probably the worst thing you can do due to all the factors in play I discussed in this article. Don’t do that. It’s like playing Russian roulette, but, in this case, there is a bullet in every chamber except one and you hope you land on the empty one.
When you weigh in, you are competing with A LOT to have it go your way. Only hopping on there once a week, and hoping you picked the right day and the right circumstances is hoping for a helluva lot.
The best way to use the scale to gauge progress is to take weekly averages and look at long-term trends. So, you’d weigh in Monday-Sunday each week and get an average. It might look like this:
Monday: 151 lbs.
Tuesday: 152.7 lbs.
Wednesday: 153.1 lbs.
Thursday: 152 lbs.
Friday 151.8 lbs.
Weekly Average: 151.9
Monday: 149.8 lbs.
Tuesday: 151 lbs.
Thursday: 152 lbs.
Friday: 150 lbs.
Weekly Average: 150.5
Doing it this way presents a much better and representative picture of what’s really going on vs. hopping on once per week and getting either a “false positive” or “false negative”. It also beats stressing the hell out and getting pissed off if your scale weight jumps up in a day.
You can also do this-and I’d encourage this-monthly as well. I LOVE an app called HAPPY SCALE. It will show you all the trends in your weight on a daily, weekly and monthly basis, provide scale weight averages, and help you better gauge your progress (all my clients use this). Download it.
You have to look at the scale merely as data. That’s all. There cannot-as hard as it may be- have an emotional attachment to it. You, to some extent, cannot control the scale...only the process and your habits.
Having more data points, having alternative ways to gauge progress, etc., will get you out of "scale jail". If you are “scale phobic”, avoiding the scale is not the answer. Learning to have a better, more rational thought process surrounding it, educating yourself, and doing what I just outlined above so you feel better about your progress (or at least have enough data to know if you need to adjust your approach or not) is what needs to happen.
And I’ll say again, the scale, even if you use it the way I just outlined, should be only ONE of many indicators you have and keep tabs on to gauge progress. Measurements, pictures, body fat, clothing fit (or some combination) should all also be used and be in your tool box.
And That’s a Wrap!
I hope you now have a better understanding of “why does my weight fluctuate daily?” Take this information and apply it...you’ll have a much more positive and productive fitness journey.
If you found this article helpful and informative, I’d REALLY appreciate it if you could share it on your social media. Best of luck on your fitness journey!
*Want to level up your nutrition, training and fat loss? Want a GPS on your fitness journey? Want someone to take all the guesswork out of the equation and provide daily accountability? Check out my budget-friendly coaching program HERE*