Everyone’s weight fluctuates. Some people may see larger fluctuations than others (whether looking to lose weight, maintain, or even gain). Sometimes even when we are trying to lose weight and are in a consistent calorie deficit, our weight stays the same for weeks or longer. Although generally scale weight will decrease over time when working on fat loss (over the course of months, not necessarily weeks), as a stand alone data point, it’s not the best method of determining progress. With clients I like to track scale weight data because it CAN be a piece to the puzzle with progress tracking.
When tracked in conjunction with measurements, pictures, and how a person feels, weight can tell a more complete story of what is happening with a person’s body composition. This is best done when looking at AVERAGES- not daily weights. Most clients I encourage to weigh themselves daily or at least several times a week (and never just once a week). Then we take those numbers to get a weekly average and compare one average to the next and watch trends over time. If weight stays the same, while measurements are decreasing- it can be a sign that muscle is increasing (and sometimes some water retention with that), while fat is decreasing.
Ideally I also like to see clients get more comfortable with seeing their weight fluctuations without having a big emotional reaction to it. Scale weight is data- the scale isn’t “lying” to you. It’s telling you how much you weigh at that point in time (not anything about your body composition). But it can be “deceiving” if you don’t take it in context with the bigger picture.
There are a lot of reasons why scale weight fluctuates and why you are gaining weight (at least temporarily)- first, remember that weight gain isn’t the same as fat gain. Some possible reasons why you might weigh more from one day to the next are:
You need to the go the bathroom! Haha! Some days (or weeks) we are just more “plugged up” than others. Eat more fiber and drink more water and things will clear themselves out shortly… TMI??
Increased stress- stress can result in holding onto more water weight and for some can also inadvertently increase your calorie intake (if you are a stress eater)- so pay attention to your little “bites, licks, tastes” throughout the day that you might not be tracking- when stress is high, this type of eating often increases.
Lack of sleep- just as with stress increases, lack of sleep can increase your water weight (NOT fat!) affecting our scale weight reading. It also can increase your appetite and make you feel more hungry, sometimes resulting in more casual snacking and binges (and casual untracked snacking can cause actual fat gain if it goes on too long and results in a calorie surplus)
It’s period time- this is a BIG one. For some, weight can increase huge amounts a few days before, during, and even after a period. And when this is a monthly occurrence, it can feel really frustrating. Some people can put on 10 lbs of weight around period time. Remember that it takes 3500 calories of a CALORIE SURPLUS to gain 1 lb of actual fat. So, 10 lbs is 35,000 extra calories. Do you think someone gaining period related weight actually ate that much surplus calories? Of course not. Don’t let a few lbs from one day to the next freak you out. Water weight subsides and it's not related to fat gain or fat loss.
Increased carbs and sodium. Does eating more carbs or more sodium result in increased fat? NO! Not unless you are eating in a surplus (and even then, if you are doing resistance training, you will likely also be putting on some muscle, not just fat). However, eating more carbs or sodium than your body is used to can temporarily increase your SCALE WEIGHT. More carbs and sodium result in more water retention (carbs are converted to glycogen which are stored in the muscles for energy- for every gram of glycogen stored, you gain approximately 2.7 grams of water). For this reason, a lot of people get confused to think that carbs are halting their fat loss progress, when in reality they aren’t giving carbs a chance. As long as you are in a calorie deficit and maintain that deficit for weeks to MONTHS, your carb intake won’t inhibit your actual fat loss. Your SCALE WEIGHT might fluctuate more because of the water weight fluctuations, but that’s irrelevant to your actual fat loss progress (another reason to take progress pictures!!).
Muscle increase. When you are NEW to consistent resistance training (less than 1-2 years of consistent resistance training, progressing your volume over time) and/or you are returning to resistant training after injury or significant time away from strength training), you can increase your muscle mass while eating in a calorie deficit. Later on in your training career, your body will require you to eat at maintenance or a calorie surplus to continue to increase actual muscle mass. But for many people, muscle increases can offset “weight” loss but not FAT LOSS if you are eating in a consistent calorie deficit. And muscle gains will increase your body’s calorie needs, thus helping you burn more fat as you continue in your calorie deficit.