Let's explore the evidence around day to day hydration and health.
Water helps us regulate our internal temperature, transports nutrients throughout our bodies, flushes waste, forms saliva, and is necessary in many other essential bodily functions. Being well hydrated will improve your mental focus, can help you to lose weight, improve your sleep quality and workouts.
Most people do not drink enough water, its often hard to know how much you should be drinking, life gets in the way and you forget, plus you need to pee all the time! But its important, and once you get into the habit of consuming plenty of water, you’ll see how achievable it is. Personally, I've been using bioelectrical impedance to assess hydration status and to become suitably hydrated is much harder than I anticipated. Going from a chronically dehydrated state to a consistently hydrated state is not done by drinking 70 ounces of water in one day.
It's interesting to note that a small percentage of the population, who consistently consume insufficient fluids are able maintain a normal total body water volume and plasma osmolality and so are not dehydrated. That said, they remain in a constant water saving state, as evidenced by consecutive days of low urine volume but they do show evidence of elevated circulating antidiuretic hormone and cortisol. These individuals show no evidence of increased thirst drive that would stimulate increased consumption of fluids. So there are some people who are relatively insensitive to physiological cues to drink enough.
This week I'm going to make suggestions for general hydration. Your hydration needs during races is going to be very different and may require a sweat test to accurately predict the necessary fluids needed to stay adequately hydrated and fueled. So how much should you drink? The National Academies of Sciences suggests that women consume a total of approximately 91 ounces of water from all beverages and foods each day and that men get approximately 125 ounces daily.
About 80 percent of your total water intake comes from drinking water and other beverages, the other 20 percent is comes from food. Therefore women will aim for 73oz per day and men will aim for 100oz. Another system that accounts for body weight, is to divide your weight by two. So if you weigh 140lbs, you should drink 70 oz per day. Whichever way you choose, try to mostly drink water or unsweetened herbal tea. Soda, sugary drinks, juices, coffee (sorry, this hurts me too!!) are not good sources of hydration.
Perrier ET. Hydration for Health: So What? Ten Advances in Recent Hydration History.Ann Nutr Metab. 2019;74 Suppl 3:4-10. doi:10.1159/000500343