Water content in overweight people is lower because fat tissue holds less water (10-40%) than muscle (70-75%). Water transports nutrients and removes waste, regulates body temperature, lubricates joints and internal organs, plays an essential role in cellular homeostasis, and can help preserve cardiovascular function. Water consumption may facilitate weight loss. Water deficits can impact physical performance, and recent research suggests that cognitive performance also may be impacted.
But let’s talk about something else. Your skin. The fact that drinking more water continuously may have a beneficial effect on your skin seems to be common knowledge these days, but is there science to back it up? Yes, there is. A study conducted in 2015 asked this question, recruiting a cohort of young women of about the same age. Group 1 had initial water consumption of <3.2 L a day, and group 2 had initial water consumption of >3.2 L a day. Both groups were asked to drink an additional 2 L of water a day for 30 days, and the effects of this intake on their skin were evaluated at the two-week mark and at the end of the experiment. Both groups demonstrated significantly modified superficial and deep skin hydration, but the change was especially pronounced in those in Group 1, whose water consumption was initially lower.
Recommendations on water intake, unlike advice for other nutrients, are often ignored, and as the experiment above shows, truly beneficial effects are achieved with much more than 8 glasses/2 L of water a day that remain the most common recommendation. But even just preventing effects of dehydration requires greater water intake.
Because water needs can vary from person to person –– and no one person will need the same amount of fluid from one day to the next, developing a recommended dietary allowance for water is challenging. The Institute of Medicine (IOM) has established an Adequate Intake (AI) for water for male - 3.7L of total water, including 3L as beverages and water, for women – 2.7L of total water, including 2.2L as beverages and water.
It is important to note that these are recommendations for total water, which includes, in addition to water, other beverages and food (soups, sauces, water-rich vegetables and fruit). What is also important to know is that all recommendations on water intake provided by the health authorities include water from all sources. This means that you can include your beverages in your count. But here’s the thing: only water is zero calories and carries no potential adverse effects of other liquid substances. So, drink up!