9 reasons your weight fluctuates that have nothing to do with fat or muscle

• Weight fluctuations don't always reflect loss or gain of fat or muscle.
• The scale can go up or down based on what you've eaten, your workouts, and time of day.
• Weighing yourself under similar circumstances is key for assessing progress, Dr. Tim Church told Insider.

Many people monitor their weight loss or gain by regularly stepping on the scale.

It can be disheartening when the number on the scale doesn't reflect your diet or exercise efforts, but it's normal for weight to fluctuate for reasons that have nothing to do with body composition.

Your weight can vary by as much as 10 pounds day to day, clinical exercise physiologist Jeffrey A. Dolgan told Shape.

From eating a salty meal to drinking alcohol, various factors can cause the scale to move up or down.

1. Your menstrual cycle

People who menstruate often experience scale fluctuations depending on where they are in their cycle.

"Women have more weight fluctuations than males due to our reproductive hormones and our menstrual cycle," personal trainer and women's health coach Hayley Madigan told Insider.

Around ovulation - typically days 12-16 of a cycle - the surge in estrogen leads to more water retention, Madigan said.

"And then again towards the very end of our cycle, because of the drop in hormones, our bodies have a rebound effect, and we once again hold onto even more water during this time of the month (around days 21-28)."

2. Eating more salt

Your weight spikes after eating more salt, which leads to water retention, Chief Medical Officer at Wondr Health Dr. Tim Church said.

"Consuming too much salt can add to the scale due to the increased water weight your body is holding," Church told Insider. "Try not to eat an especially salty meal the night before a weigh-in."

According to a 2017 meta-analysis by various research centers published in the Annals of Nutrition and Metabolism, it can take a few days for sodium-related water retention to go down.

3. Eating higher carb

Similarly, we retain water when we eat more carbs.

"When we eat high carb foods, our bodies hold on to more water in order to digest the carbohydrates and use them for energy - this is a normal human response so don't let it put you off eating carbs," Madigan said.

With every 1g of carbs we eat, our bodies hold on to an extra 3g of water, she explained, so when you eat a 200g portion of carbs, you will weigh 800g more, which is nearly 2lbs.

"This is only water weight not fat," Madigan said.

4. Being dehydrated

If you've ever weighed yourself the morning after a boozy night and been surprised to find yourself lighter, it's because you're dehydrated.

"When we don't drink enough water our bodies will retain the water it has as a survival response," Madigan said.

When we consume diuretics like caffeine and alcohol, it briefly reduces water retention in the body so we weigh less, but there's a rebound effect, according to Madigan.

"When you start drinking water normally again your body will retain more of it to counteract the alcohol/caffeine and therefore your weight will jump up again," Madigan said.

5. Technical problems

Sometimes the number on the scale has nothing to do with you, but rather the scale and setting.

"There are a remarkable number of factors that go into getting an accurate weight, even at a medical office," Church said.

Common technical and equipment errors he sees include low or bad batteries, placing the scale on an uneven surface or carpet, and bad wiring due to moisture and poor calibration.

6. Wearing different clothes

Church said people generally underestimate how much their clothes weigh, especially shoes, so it's best to weigh yourself naked or wearing minimal clothes to ensure an accurate reading.

"You should also stay consistent and wear the same thing at each weigh-in to ensure the reading is as accurate as possible," he said.

7. Doing a heavy workout

A heavy workout, particularly strength-training or if you're new to exercise, can cause temporary weight gain of 3-4 lbs - this is water retention due to muscle inflammation, physical therapist Gary Calabrese told the Cleveland Clinic.

Hard exercise causes micro tears to the muscle fibers, and healing those tears requires holding on to water. This is called exercise-induced muscle damage, and the inflammation is a result of a build-up of white blood cells in the tissues.

8. The time of day

Over the course of the day, our weight is affected by our meals, fluid-consumption, and bathroom visits.

With this in mind, you should try and weigh yourself at the same time of day for a fair comparison, ideally first thing in the morning.

"I always recommend weighing yourself in the morning and not at night, as it's important to weigh in with an empty stomach and bladder so that the readings are consistent week after week," Church said.

If you haven't emptied your bowel for a while, that can affect the scale reading, as can whether you ate dinner early or late the night before.

Try and keep your weigh-ins as consistent as possible

While measurements and progress photos can be helpful in monitoring progress, Church said the scale is still a useful tracking tool.

The most important factor to remember, he said, is weighing yourself under similar circumstances week after week, such as using the same scale at home, to ensure your readings are as accurate and consistent as possible.

However, because weekly weigh-ins can be affected by all the above factors, some people prefer to weigh every day and then take a weekly average.

"Another thing to remember is the number on the scale isn't the full picture of where you are in your health journey, but just one component," Church said. "Make sure you're communicating to your doctor about other factors, including how you feel day-to-day or any necessary blood work and health screenings to have a better idea of your health."