6 Common Causes for Daily Weight Fluctuations

Dr. Christopher McGowan
September 25, 2022

Your bathroom scale can be friend or foe. When the pounds are coming off, you’re likely to feel excited and motivated to continue with your weight loss efforts. However, noticing an increase of a few pounds can be upsetting and discouraging for many.

Don’t fret—overnight bodyweight fluctuations are normal and are not necessarily an indicator of “true” weight gain. In fact, the average adult’s weight may fluctuate anywhere from five to six pounds on any given day. While it is important to be aware that consistent overeating will lead to real weight gain overtime, daily weight fluctuations can often be attributed to factors such as fluid retention, water consumption, exercise, sleep and stress levels, constipation and/or a woman’s menstrual cycle. Here’s everything you need to know about the many causes of weight fluctuation.

Extra Fluid Retention

Your body’s retention of excess fluids often comes from eating foods that are higher in sodium (salt) and carbohydrates. Some common signs of fluid retention include swelling or puffiness, particularly in the arms or legs; an increase in abdomen size, achy joints or limbs, skin tightness, and weight fluctuations.

  • Sodium: For general health, the USDA’s Dietary Guidelines for Americans recommends adults consume only 2,300 mg or less of sodium per day—equal to about one teaspoon of table salt. Because the body keeps sodium levels well-regulated, a higher intake of salt will cause fluid shifts and water retention. However, these excess fluids are excreted through urination, so drinking plenty of fluids should bring sodium levels back to normal.
  • Carbohydrates: In general, carbohydrates (carbs) retain water, specifically about 3 grams of water for every gram of carbohydrate. But, this doesn’t mean you should avoid them altogether—nor do they alone lead to fat or weight gain. Carbohydrates are an essential source of energy for the body, and they play an important role in glucose and insulin action, as well as fat and cholesterol metabolism.

Water Consumption

Your body is made up of 60 to 70 percent water. Not only that, water is critical to proper bodily functions, such as metabolic reactions, carrying nutrients and waste products, the regulation of body temperature and blood volume, and fluid balance. Fluid balance is regulated by the kidneys and any imbalance can lead to either fluid retention or increased urination. To keep your body in a normal fluid zone, you should drink about eight to 10 cups of water per day. If you aren’t drinking enough water, you run the risk of becoming dehydrated. Dehydration is the gradual depletion of bodily fluids when fluid losses exceed fluid intake. In this state, your body wants to hold on more tightly to any water it does have, therefore causing water retention and bloating. As a result, dehydration will likely cause the numbers on your scale to go up and your clothes to feel a bit tight. Increasing your water intake can help balance out the fluids in your system and actually get rid of any excess water.

  • Exercise – During strength training, muscle fibers are broken down, which in turn causes inflammation. Your muscles will then store water to repair this damage, resulting in fluid retention. Soon after, you might notice an increase when you step on the scale. However, exercise also causes fluid loss, which can lead to weight fluctuations in the other direction as well.
  • Sleep & Stress – Lack of sleep and high levels of stress can each lead to fluctuations on the scale. For example, hunger and appetite are regulated by the hormones ghrelin, leptin and cortisol. Not getting enough sleep will alter the regulation of these hormones, causing you to feel hungrier and likely eat more. Meanwhile, cortisol is released under stress, stimulating a fight or flight response. Cortisol can increase your appetite as well as your cravings for sweets, fats, and salt. Adults should get about seven hours or more of sleep per night to avoid sleep deprivation, and practices like yoga, meditation, walking, and journaling can help with stress management.
  • Constipation – Normal bowel movement vary greatly by person—ranging from anywhere between a few times per week to three times per day. Understanding your own bowel habits can help you identify if irregularity or constipation may be leading to unexplained weight gain. Constipation is the difficult or infrequent passage of stool and is often caused by dehydration, a lack of dietary fiber, physical inactivity, or medication side effects. Signs and symptoms include straining during bowel movements, hard stools, infrequent bowel movements, abdominal discomfort, backaches, and excess gas. For healthy bowels, you should maintain a good level of hydration while eating a high-fiber diet and staying physically active. Fiber can be found in whole grains, fruits, vegetables, legumes, seeds, and nuts. The Dietary Guidelines for Americans recommends different amounts of daily fiber based upon sex and age. Women age 14-50 need somewhere between 25 and 28 grams per day, while men age 14-50 need somewhere between 31 and 34 grams.
  • Menstrual Cycle – Estrogen and progesterone are the hormones needed to regulate a woman’s menstrual cycle and support pregnancy. They also impact bodily fluids. Many women experience physical symptoms during their menstrual cycle due to changes in estrogen and progesterone, including fluid retention and bloating. Because the levels of these hormones change over the course of menstruation, a woman’s weight will likely fluctuate throughout her cycle as well.

Don’t Be Discouraged By Weight Fluctuations

There are many reasons for daily weight fluctuations; therefore, you shouldn’t allow the number on your scale to be the only indicator of your weight loss success. It’s actually quite uncommon to consistently see the same weight on your scale on a daily basis. As explained above, most fluctuations are related to changes in water weight and normal bodily functions. However, if your weight continues to increase for about a week, you may want to check in with your True You team.

Using Best Practices on the Scale

For the most consistent results, be sure to weigh under the same circumstances each time—wearing the same clothes, at the same time of day, and the same day of the week. Most importantly, try to limit how often you weigh in. We recommend every other week, but if you can’t handle that—limit yourself to one or two times per week. Remember that weight loss or gain is never linear and the scale is only one indicator of your progress. Body weight alone can’t define your health or happiness—we know that each one of our True You Weight Loss patients is so much more than just a number on the scale! 

Dr. Christopher McGowan
Dr. Christopher McGowan

Dr. Christopher McGowan, MD, a leader in endobariatrics, specializes in non-surgical obesity treatments and is triple-board-certified in Internal Medicine, Gastroenterology, and Obesity Medicine. Renowned for pioneering endoscopic sleeve gastroplasty (ESG) with over 2,000 procedures, his global influence and research contributions define him as a top expert.

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