• Author:
    Betty Kovacs, MS, RD

    Betty is a Registered Dietitian who earned her B.S. degree in Food and Nutrition from Marymount College of Fordham University and her M.S. degree in Clinical Nutrition from New York University. She is the Co-Director and Director of nutrition for the New York Obesity Research Center Weight Loss Program.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Take the Caffeine Quiz!

How much fluid do we need?

Anyone who has ever been on a diet will tell you that you are supposed to drink at least 8 cups of water a day. Everyone knows this, but finding the evidence to support it is another story. In 2004, the Food and Nutrition Board established recommendations on the intake of water. The recommendations were set based on the necessary amount needed to maintain health and reduce chronic disease risk:

  • The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide.
  • The report did not specify exact requirements for water but set general recommendations for women at approximately 2.7 L (91 oz) of total water (from all beverages and foods) each day and men at an average of approximately 3.7 L (125 oz daily) of total water.
  • The panel did not set an upper level for water.
  • About 80% of people's total water intake comes from drinking water and beverages (including caffeinated beverages), and the other 20% is derived from food.
  • Prolonged physical activity and heat exposure will increase water losses and therefore may raise daily fluid needs, although it is important to note that excessive amounts of fluid can be life threatening. Acute water toxicity has been reported due to rapid consumption of large quantities of fluids that greatly exceeded the kidney's maximal excretion rate of approximately 0.7 to 1.0 L/hour.

The report allows all fluids to be counted into your total intake, so people began eliminating water from their diets in favor of other liquids. However, the recommendations were not intended to reduce water consumption. Water should be your primary source of fluid. Our bodies are made up of over 60% water, not coffee, tea, juice, or soda. Caffeine is a treat that will have health consequences when consumed in excessive amounts and is not safe for everyone. Set limits on the treats that you allow yourself, and be sure to give your body what it needs in adequate amounts. Too much of anything is just too much for our bodies to handle.

Medically reviewed by Martin E Zipser, MD; American Board of Surgery


Al-Saleh, I, I. El-Doush, B. Grisellhi, and S. Coskun. "The Effect of Caffeine Consumption on the Success Rate of Pregnancy as Well Various Performance Parameters of In-Vitro Fertilization Treatment." Med Sci Monit. 16.12 Nov. 2010: CR598-605. American Beverage Association

American Heart Association

Center for the Science in the Public Interest

"Children Increasingly Consuming Caffeine." National Drug Strategy Network. May-June 1998. <>.
Cohen, D.L. J Clin Hypertens. 8.10 Oct. 2006: 744-745.

"Is It Really Decaf?" Consumer Reports. Nov. 2007. <>.
"Caffeine Content of Food & Drugs." Center for Science in the Public Interest. Sept. 2007. <>.

Department of Health and Human Services

Diepvens, K. Am J Physiol Integr Comp Physiol. 292.1 Jan. 2007: R77-85.

Dixit, A. Indian J Phsyiol Pharmacol. 50.2 Apr.-June 2006: 175-180.
Dulloo, A.G. Am J Clin Nutr. 70.6 Dec. 1999: 1040-1045.

Eddy, N.B. J Pharmacol Exp Ther. 33 (1928): 167-174.

Fray, C.D. J Amer Diet Assoc. 105 (2005): 110-13.
Goldstein, A. Exp Clin Psychopharmacol. 5.4 Nov. 1997: 388-392.

Grandjean, A.C. J Am Coll Nutr. 19.5 Oct. 2000: 591-600.

Greenberg, J. Int J Obes (Lond). 29.9 Sept. 2005: 1121-1129.

Greenberg, J.A. Am J Clin Nutr. 85 June 2007: 392-398.

Harnack, L. J Am Diet Assoc. 99 (1999): 436-441.

Howland, J. Addiction. 106.2 (2011): 335-341.
Hughes, J.R. Am J Psychiatry. 149.1 Jan. 1992: 33-40.

Iso, H., et al. "The Relationship Between Green Tea and Total Caffeine Intake and Risk for Self-Reported Type 2 Diabetes Among Japanese Adults." Ann Intern Med. 144.8 Apr. 18, 2006: 554-562.
Juliano, L.M. Psychopharmacology. 176.1 Oct. 2004: 1-29.

Kendler, K.S. Am J Psychiatry. 156.2 Feb. 1999: 223-228.
Lane, J.D. Psychosom Med. 552.3 May-June 1990: 320-326.
March of Dimes
Maslova, E. Am J Clin Nutr. 92.5 Nov. 2010: 1120-1132.
Mayo Clinic
National Academy of Sciences
Neuhauser-Berthold, M. Ann Nutr Metab. 41 (1997): 29-36.
Noordizij, M. J Hypertens. 23.5 May 2005: 921-928.
Ogawa, N. Psychiatry Clin Neurosci. 61.3 June 2007: 263-268.
Passmore, A.P. Clin Sci. 72 June 1987: 749-756.
Rapuri, P.B. Am J Clin Nutr. 74 Nov. 2001: 694-700.
Satel, S. Am J Drug Alcohol Abuse. 32.4 2006: 493-502.
Schuh, K.J. Psychopharmacology. 130.4 1997: 320-326.
Smith, A.P. Hum Psychopharmacol. 20.6 Aug. 2005: 441-445.
Temple, J. Neurosci Biobehav Rev. 33.6 Jan. 2009: 793-806.
The Beverage Institute for Health and Wellness
Tucker, K.L. Am J Clin Nutr. 84.4 Oct. 2006: 936-942.
U.S. Department of Agriculture
Warner, Jennifer. "Decaf Coffee Isn't Caffeine-Free." WebMD. Oct. 11, 2006. <>.
Westerterp-Plantenga, M.S. Obes Res. 13.7 July 2005: 1195-1204.
Winkelmayer, W.C. "Habitual Caffeine Intake and the Risk of Hypertension in Women." JAMA. 294.18 Nov. 9, 2005: 2330-2335.

Medically Reviewed by a Doctor on 2/18/2015
Caffeine Quiz: Test Your Medical IQ

Subscribe to MedicineNet's Weight Loss/Healthy Living Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Health Solutions From Our Sponsors