Julie Upton, R.D., co-founder of the nutrition website Appetite for Health, told Women’s Health, “People weigh less when they wake up because the body is slightly dehydrated,” and that perfectly explains how water retention can make people weigh more. In contrast, loss of water can make people weigh less. Sonya Angelone, R.D., a spokeswoman for the Academy of Nutrition and Dietetics, also told the publication that your body may have burned calories while sleeping to fuel essential bodily functions like breathing or sweating, which also dehydrates the body.
PopSugar Fitness agrees that dehydration is one of the primary reasons you weigh less in the morning. Ruby Shah, MD, a double board-certified internist at Texas Health Presbyterian Hospital Plano, told the publication, “Since water accounts for about 50 to 60 percent of an adult’s body weight, these small changes can add or subtract a few pounds.” Dr. Shah added that not eating and drinking overnight and going to the bathroom in the middle of the night can be essential factors in weighing less. Now, you can understand why last night’s weight is so different from this morning.
It is best not to obsess about your weight and weigh yourself too often, though. However, if you want to keep track of your weight for health reasons, Healthline recommends weighing yourself first thing in the morning after using the restroom before eating and drinking because that is when you will weigh your least.
