This Is Why You Weigh Less in the Morning

If you’ve ever stepped on the scale in the a.m. and felt great about your weight-loss progress only to realize you’ve gained four pounds by bedtime, we feel your pain.

While the number on the scale can be highly frustrating, you might wonder why the hell you’re lighter in the morning than you are the rest of the day—and which number is a more accurate measure of whether you’re actually losing weight.

“People weigh less when they wake up because the body is slightly dehydrated,” says Julie Upton, R.D., co-founder of the nutrition website Appetite for Health.

That slight dehydration can equal a noticeable drop in weight, says Sonya Angelone, R.D., a spokeswoman for the Academy of Nutrition and Dietetics. “Since two cups of water weighs one pound, even modest dehydration or water retention can affect weight throughout the day,” she says.

Conversely, drinking water before bed can keep you from being dehydrated in the morning and result in a higher number, says Angelone. Though, she points out, if you get up to pee during the night you won’t retain much of that H20.

It’s also possible that you weigh less because you’ve burned up calories from the food you ate the night before in order to fuel basic bodily functions, like breathing and generating body heat, says Angelone.

Finally, weighing yourself after your morning workout could result in a lower than normal reading, thanks to sweating buckets, says Angelone. “But it’s not a true reflection of any changes in body fat,” she says.

Angelone discourages weighing yourself after dinner, since it’s usually the biggest meal of the day. “This weight will include the weight of the food and beverage you just consumed,” she points out.

With all of that being said, there’s no perfect time of day to weigh yourself, says Upton. As long as you scale in around the same time of day consistently, you’ll have an accurate comparison.

It’s also not a bad idea to hop on naked so you can get an even more on-point idea of where your weight is.

No matter when you weigh yourself, don’t freak if you notice that your weight went up a pound or two one day and down the next. Your weight is pretty variable, says Upton. But if it goes up and stays up, or vice versa, you know things are changing. “The number on the scale should be used as a relative number not absolute,” says Upton.