# Do heavier people need to drink more water?

A 2013 article by Yuri Elkaim, a holistic nutritionist, in the health section of U.S. News & World Report says:

if you weigh 200 pounds [90 kg], you would need 100 ounces [3 l] of water per day if you're not doing anything strenuous. If you're working out, hiking, at a high altitude or outdoors a great deal, you're going to need to add to those 100 ounces.

Is it true that if you weigh more you need to drink more water?

• Your citation says "if you work out or hike", not "if you weigh more". Please cite correctly. Sep 20, 2020 at 17:34
• I see the implicit claim corresponding weight to water consumption. Looks fine to me. Sep 21, 2020 at 1:01
• @fredsbend: but it's explicit in the linked article: "The basic equation for determining this is by dividing your body weight in half. So, if you weigh 200 pounds, you would need 100 ounces of water per day" Sep 21, 2020 at 8:26
• A point: Fat cells don't multiply, only gain volume. Muscle cells do. I don't have any references, but number of cells might have correlation with water consumption needs. Sep 22, 2020 at 7:46

Newborn babies drink ~750 ml of milk:

(45-90 milliliters) every 2-3 hours.

So the claim

The basic equation for determining this is by dividing your body weight in half.

is certainly not true without further restrictions on age.

There was a study regarding the 8 times 8 glasses rule (2002) which turned out:

I have found no scientific proof that we must “drink at least eight glasses of water a day,” nor proof, it must be admitted, that drinking less does absolutely no harm.

The reference list for water in Germany, Austria and Switzerland (2015) lists slightly different values by age, but not by weight:

They say the values can change with increased energy exchange, heat, dry air, eating salt, high protein input or illness like fever, vomiting or dirrahea. Weight is not mentioned.

If it were scientifically proved in 2013, I would expect the 2015 recommendations to consider these studies (or at least some update until 2020). The fact that Yuri Elkaim does not mention a study, makes me believe that it's just his own, limited observations.

• The values in the table are ml beverages per day and the very same table has another column listing water in beverages and solid food in ml/kg body mass. That column lists 35 - 30 ml/kg for adults (more during lactation). Sep 24, 2020 at 16:04
• "divide in half" is badly worded, as it sounds a lot like "divide by half", which is the same as "multiply by two". And if 90 kg = 100 oz, then assuming those are liquid oz and a human specific gravity close to 1, that's 90 l = 3l. The "take half" depends on taking weight in pounds and volume in ounces. We could dispense with having to specify units if we just said "Drink 3.3% of your volume per day". Sep 26, 2020 at 8:56
• @cbeleitesunhappywithSX: I think you're right. You should give that as an answer and I'll delete mine. I'm too stupid Sep 26, 2020 at 20:37