Drink two cups of cold water on an empty stomach a few times a day for weight loss.
Friday Favorites: Optimizing Water Intake to Lose Weight
5/5 - (70 votes)
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
Drink two cups of water and you can get a surge of the adrenal hormone noradrenaline in your bloodstream, as if you just smoked a few cigarettes or downed a few cups of coffee, which boosts your metabolic rate up to 30 percent within an hour––which, when put to the test in randomized controlled trials, appeared to accelerate weight loss by 44 percent, certainly making it the safest, simplest, and cheapest way to boost your metabolism.
Now, if you’re on a beta blocker drug, this entire strategy may fail. (Beta blockers are typically prescribed for heart conditions or high blood pressure, and tend to end with the letters “lol,” such as atenolol, nadolol, or propranolol, sold as Tenormin, Corgard, or Inderal, respectively.) So, for example, if you give people the beta blocker drug metoprolol (sold as Lopressor) before they chug their two cups of water, the metabolic boost is effectively prevented. This makes sense, since the “beta” that’s being blocked in beta blockers are the beta receptors triggered by noradrenaline. Otherwise, though, the water should work. But what’s the best dose, type, temperature, and timing?
Just a single cup may be sufficient to rev up the noradrenaline nerves, but additional benefit is seen at two or more cups. Caution: one should never drink more than three cups in an hour, though, since that starts to exceed the amount of fluid your kidneys can handle. If you have heart or kidney failure, your physician may not want you drinking extra water at all, but even with healthy kidneys, any more than three cups of water an hour can start to critically dilute the electrolytes in your brain with potentially critical consequences. (In How Not to Diet, I talk about the first patient I ever killed in the hospital as an intern. It was a guy who drunk himself to death—with water. He suffered from a neurological condition that causes pathological thirst. I knew enough to order his liquids to be restricted and have his sink shut off, but didn’t think to turn off his toilet.).
Anyway, does it have to be plain, straight water? It shouldn’t seem to matter, right? Water is water, whether flavored or sweetened in some diet drink. But it does matter. When trying to prevent fainting before blood donation, something like juice doesn’t work as well as plain water. When trying to keep people from getting dizzy when they stand up, water works. But, the same amount of water with salt added doesn’t. What’s going on?
We used to think the trigger was stomach distention. When we eat, our body shifts blood flow to our digestive tract, in part by releasing noradrenaline to pull in blood from our limbs. This has been called the gastrovascular reflex. So, drinking water was thought to be just a zero-calorie way of stretching our stomach. But instead, drink two cups of saline (basically salt water), and the metabolic boost vanishes; so, stomach expansion can’t explain the water effect.
We now realize our body appears to detect osmolarity, the concentration of stuff within a liquid. Covertly slip liquids of different concentrations into people’s stomachs with a feeding tube, and you can demonstrate this by monitoring sweat production (which is a proxy for noradrenaline release). This may be a spinal reflex, as it’s preserved in quadriplegics, or picked up by the liver, as we see less noradrenaline release in liver transplant patients (who’ve had their liver nerves severed). Whichever the pathway, our body can tell. Thought we only had five senses? The current count is upwards of 33 (so, maybe the Bruce Willis movie should have been called The Thirty-FOURTH Sense).
In my Daily Dozen recommendation, I rank certain teas as among the healthiest beverages. After all, they have all the water of water with an antioxidant bonus. But from a weight-loss perspective, plain water may have an edge. That may explain the studies showing overweight and obese individuals randomized to replace diet beverages with water lost significantly more weight. This was chalked up to getting rid of all those artificial sweeteners, but maybe instead the diet drinks were too concentrated to offer the same water-induced metabolic boost. Diet soda, like tea, has about ten times the concentration of dissolved substances compared to tap water. So, plain water on an empty stomach may be the best.
Does the temperature of the water matter? In a journal published by the American Society of Mechanical Engineers, an engineering professor proposed that the “secret” of a raw food diet for weight loss was the temperature at which the food was served. To bring two cups of even just room temperature water up to body temperature, he calculated the body would have to dip into its fat stores and use up 6,000 calories. Just do the math, he says: a calorie is defined as the amount of energy required raise one gram of water one degree Celsius. So, since two cups of water is about 500 grams, and the difference between room temp and body temp is about a dozen degrees Celsius. 500 x 12 = 6,000-plus calories needed.
Anyone see the mistake? In nutrition, a “calorie” is actually a kilocalorie, a thousand times bigger than the same word used in the rest of the sciences. Confusing, right? Still, I’m shocked the paper was even published.
So, drinking two cups of room temperature water actually only takes six calories to warm up, not 6,000. Now, if you were a hummingbird drinking four times your body weight in chilly nectar, you could burn up to 2 percent of your energy reserves warming it up, but it doesn’t make as much of a difference for us.
What about really cold water, though? A letter called “The Ice Diet” published in the Annals of Internal Medicine estimated that eating about a quart of ice—like a really, really big snow cone with no syrup—could rob our body of more than 150 calories, the “same amount of energy as the calorie expenditure in running one mile.” It’s not like you directly burn fat to warm up the water, though. What your body does is just corrals more of the waste heat you normally give off by constricting blood flow to your skin. But how does it do that? Noradrenaline!
If you compare drinking body-temperature water, to room-temperature water, to cold water, there’s only a significant constriction in blood flow to the skin after the room temp and cold water. And neither the warm nor tepid water could boost metabolic rate as much as cold (fridge temperature) water. So, your body does, after all, end up at least indirectly burning off more calories when you drink your water cold.
So, two cups of cold water on an empty stomach a few times a day. Does it matter when? Yes, watch my Evidence-Based Weight Loss lecture to see how you can add the benefit of negative-calorie preloading by drinking that water right before your meals.
Please consider volunteering to help out on the site.
- Scott EM, Greenwood JP, Gilbey SG, Stoker JB, Mary DA. Water ingestion increases sympathetic vasoconstrictor discharge in normal human subjects. Clin Sci. 2001;100(3):335-42.
- Jordan J, Shannon JR, Black BK, et al. The pressor response to water drinking in humans: a sympathetic reflex? Circulation. 2000;101(5):504-9.
- Boschmann M, Steiniger J, Hille U, et al. Water-induced thermogenesis. J Clin Endocrinol Metab. 2003;88(12):6015-9.
- Dennis EA, Dengo AL, Comber DL, et al. Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults. Obesity (Silver Spring). 2010;18(2):300-7.
- Shen WK, Sheldon RS, Benditt DG, et al. 2017 ACC / AHA / HRS guideline for the evaluation and management of patients with syncope: a report of the American College of Cardiology / American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2017;136(5):e60-122.
- Verbalis JG, Goldsmith SR, Greenberg A, Schrier RW, Sterns RH. Hyponatremia treatment guidelines 2007: expert panel recommendations. Am J Med. 2007;120(11 Suppl 1):S1-21.
- Noakes TD, Wilson G, Gray DA, Lambert MI, Dennis SC. Peak rates of diuresis in healthy humans during oral fluid overload. S Afr Med J. 2001;91(10):852-7.
- Lu CC, Li MH, Ho ST, et al. Glucose reduces the effect of water to promote orthostatic tolerance. Am J Hypertens. 2008;21(11):1177-82.
- Raj SR, Biaggioni I, Black BK, et al. Sodium paradoxically reduces the gastropressor response in patients with orthostatic hypotension. Hypertension. 2006;48(2):329-34.
- van Orshoven NP, Oey PL, van Schelven LJ, Roelofs JM, Jansen PA, Akkermans LM. Effect of gastric distension on cardiovascular parameters: gastrovascular reflex is attenuated in the elderly. J Physiol (Lond). 2004;555(Pt 2):573-83.
- Boschmann M, Steiniger J, Franke G, Birkenfeld AL, Luft FC, Jordan J. Water drinking induces thermogenesis through osmosensitive mechanisms. J Clin Endocrinol Metab. 2007;92(8):3334-7.
- May M, Jordan J. The osmopressor response to water drinking. Am J Physiol Regul Integr Comp Physiol. 2011;300(1):R40-6.
- Tank J, Schroeder C, Stoffels M, et al. Pressor effect of water drinking in tetraplegic patients may be a spinal reflex. Hypertension. 2003;41(6):1234-9.
- May M, Gueler F, Barg-Hock H, et al. Liver afferents contribute to water drinking-induced sympathetic activation in human subjects: a clinical trial. PLoS ONE. 2011;6(10):e25898.
- Durie B. Senses special: doors of perception. New Sci. 2005;2484.
- Madjd A, Taylor MA, Delavari A, Malekzadeh R, MacDonald IA, Farshchi HR. Effects on weight loss in adults of replacing diet beverages with water during a hypoenergetic diet: a randomized, 24-wk clinical trial. Am J Clin Nutr. 2015;102(6):1305-12.
- Madjd A, Taylor MA, Delavari A, Malekzadeh R, MacDonald IA, Farshchi HR. Beneficial effects of replacing diet beverages with water on type 2 diabetic obese women following a hypo-energetic diet: a randomized, 24-week clinical trial. Diabetes Obes Metab. 2017;19(1):125-32.
- Dubnov-Raz G, Constantini NW, Yariv H, Nice S, Shapira N. Influence of water drinking on resting energy expenditure in overweight children. Int J Obes (Lond). 2011;35(10):1295-300.
- Maughan RJ, Watson P, Cordery PA, et al. A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index. Am J Clin Nutr. 2016;103(3):717-23.
- Wong KV. Temperature of food and drink intake matters. J Energy Resour Technol. 2016;138(5):054701.
- Bradley TH, Melby CL. Discussion: “Temperature of Food and Drink Intake Matters” (Wong KV, 2016, ASME J. Energy Resour. Technol., 138(5), p. 054701). J Energy Resour Technol. 2017;139(1):015501-1-2.
- Weiner BC, Weiner AC. The ice diet. Ann Intern Med. 2010;153(4):279.
- Kocełak P, Zak-Gołąb A, Rzemieniuk A, et al. The influence of oral water load on energy expenditure and sympatho-vagal balance in obese and normal weight women. Arch Med Sci. 2012;8(6):1003-8.
- Girona M, Grasser EK, Dulloo AG, Montani JP. Cardiovascular and metabolic responses to tap water ingestion in young humans: does the water temperature matter? Acta Physiol (Oxf). 2014;211(2):358-70.
Video production by Glass Entertainment
Motion graphics by Avocado Video
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
Drink two cups of water and you can get a surge of the adrenal hormone noradrenaline in your bloodstream, as if you just smoked a few cigarettes or downed a few cups of coffee, which boosts your metabolic rate up to 30 percent within an hour––which, when put to the test in randomized controlled trials, appeared to accelerate weight loss by 44 percent, certainly making it the safest, simplest, and cheapest way to boost your metabolism.
Now, if you’re on a beta blocker drug, this entire strategy may fail. (Beta blockers are typically prescribed for heart conditions or high blood pressure, and tend to end with the letters “lol,” such as atenolol, nadolol, or propranolol, sold as Tenormin, Corgard, or Inderal, respectively.) So, for example, if you give people the beta blocker drug metoprolol (sold as Lopressor) before they chug their two cups of water, the metabolic boost is effectively prevented. This makes sense, since the “beta” that’s being blocked in beta blockers are the beta receptors triggered by noradrenaline. Otherwise, though, the water should work. But what’s the best dose, type, temperature, and timing?
Just a single cup may be sufficient to rev up the noradrenaline nerves, but additional benefit is seen at two or more cups. Caution: one should never drink more than three cups in an hour, though, since that starts to exceed the amount of fluid your kidneys can handle. If you have heart or kidney failure, your physician may not want you drinking extra water at all, but even with healthy kidneys, any more than three cups of water an hour can start to critically dilute the electrolytes in your brain with potentially critical consequences. (In How Not to Diet, I talk about the first patient I ever killed in the hospital as an intern. It was a guy who drunk himself to death—with water. He suffered from a neurological condition that causes pathological thirst. I knew enough to order his liquids to be restricted and have his sink shut off, but didn’t think to turn off his toilet.).
Anyway, does it have to be plain, straight water? It shouldn’t seem to matter, right? Water is water, whether flavored or sweetened in some diet drink. But it does matter. When trying to prevent fainting before blood donation, something like juice doesn’t work as well as plain water. When trying to keep people from getting dizzy when they stand up, water works. But, the same amount of water with salt added doesn’t. What’s going on?
We used to think the trigger was stomach distention. When we eat, our body shifts blood flow to our digestive tract, in part by releasing noradrenaline to pull in blood from our limbs. This has been called the gastrovascular reflex. So, drinking water was thought to be just a zero-calorie way of stretching our stomach. But instead, drink two cups of saline (basically salt water), and the metabolic boost vanishes; so, stomach expansion can’t explain the water effect.
We now realize our body appears to detect osmolarity, the concentration of stuff within a liquid. Covertly slip liquids of different concentrations into people’s stomachs with a feeding tube, and you can demonstrate this by monitoring sweat production (which is a proxy for noradrenaline release). This may be a spinal reflex, as it’s preserved in quadriplegics, or picked up by the liver, as we see less noradrenaline release in liver transplant patients (who’ve had their liver nerves severed). Whichever the pathway, our body can tell. Thought we only had five senses? The current count is upwards of 33 (so, maybe the Bruce Willis movie should have been called The Thirty-FOURTH Sense).
In my Daily Dozen recommendation, I rank certain teas as among the healthiest beverages. After all, they have all the water of water with an antioxidant bonus. But from a weight-loss perspective, plain water may have an edge. That may explain the studies showing overweight and obese individuals randomized to replace diet beverages with water lost significantly more weight. This was chalked up to getting rid of all those artificial sweeteners, but maybe instead the diet drinks were too concentrated to offer the same water-induced metabolic boost. Diet soda, like tea, has about ten times the concentration of dissolved substances compared to tap water. So, plain water on an empty stomach may be the best.
Does the temperature of the water matter? In a journal published by the American Society of Mechanical Engineers, an engineering professor proposed that the “secret” of a raw food diet for weight loss was the temperature at which the food was served. To bring two cups of even just room temperature water up to body temperature, he calculated the body would have to dip into its fat stores and use up 6,000 calories. Just do the math, he says: a calorie is defined as the amount of energy required raise one gram of water one degree Celsius. So, since two cups of water is about 500 grams, and the difference between room temp and body temp is about a dozen degrees Celsius. 500 x 12 = 6,000-plus calories needed.
Anyone see the mistake? In nutrition, a “calorie” is actually a kilocalorie, a thousand times bigger than the same word used in the rest of the sciences. Confusing, right? Still, I’m shocked the paper was even published.
So, drinking two cups of room temperature water actually only takes six calories to warm up, not 6,000. Now, if you were a hummingbird drinking four times your body weight in chilly nectar, you could burn up to 2 percent of your energy reserves warming it up, but it doesn’t make as much of a difference for us.
What about really cold water, though? A letter called “The Ice Diet” published in the Annals of Internal Medicine estimated that eating about a quart of ice—like a really, really big snow cone with no syrup—could rob our body of more than 150 calories, the “same amount of energy as the calorie expenditure in running one mile.” It’s not like you directly burn fat to warm up the water, though. What your body does is just corrals more of the waste heat you normally give off by constricting blood flow to your skin. But how does it do that? Noradrenaline!
If you compare drinking body-temperature water, to room-temperature water, to cold water, there’s only a significant constriction in blood flow to the skin after the room temp and cold water. And neither the warm nor tepid water could boost metabolic rate as much as cold (fridge temperature) water. So, your body does, after all, end up at least indirectly burning off more calories when you drink your water cold.
So, two cups of cold water on an empty stomach a few times a day. Does it matter when? Yes, watch my Evidence-Based Weight Loss lecture to see how you can add the benefit of negative-calorie preloading by drinking that water right before your meals.
Please consider volunteering to help out on the site.
- Scott EM, Greenwood JP, Gilbey SG, Stoker JB, Mary DA. Water ingestion increases sympathetic vasoconstrictor discharge in normal human subjects. Clin Sci. 2001;100(3):335-42.
- Jordan J, Shannon JR, Black BK, et al. The pressor response to water drinking in humans: a sympathetic reflex? Circulation. 2000;101(5):504-9.
- Boschmann M, Steiniger J, Hille U, et al. Water-induced thermogenesis. J Clin Endocrinol Metab. 2003;88(12):6015-9.
- Dennis EA, Dengo AL, Comber DL, et al. Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults. Obesity (Silver Spring). 2010;18(2):300-7.
- Shen WK, Sheldon RS, Benditt DG, et al. 2017 ACC / AHA / HRS guideline for the evaluation and management of patients with syncope: a report of the American College of Cardiology / American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2017;136(5):e60-122.
- Verbalis JG, Goldsmith SR, Greenberg A, Schrier RW, Sterns RH. Hyponatremia treatment guidelines 2007: expert panel recommendations. Am J Med. 2007;120(11 Suppl 1):S1-21.
- Noakes TD, Wilson G, Gray DA, Lambert MI, Dennis SC. Peak rates of diuresis in healthy humans during oral fluid overload. S Afr Med J. 2001;91(10):852-7.
- Lu CC, Li MH, Ho ST, et al. Glucose reduces the effect of water to promote orthostatic tolerance. Am J Hypertens. 2008;21(11):1177-82.
- Raj SR, Biaggioni I, Black BK, et al. Sodium paradoxically reduces the gastropressor response in patients with orthostatic hypotension. Hypertension. 2006;48(2):329-34.
- van Orshoven NP, Oey PL, van Schelven LJ, Roelofs JM, Jansen PA, Akkermans LM. Effect of gastric distension on cardiovascular parameters: gastrovascular reflex is attenuated in the elderly. J Physiol (Lond). 2004;555(Pt 2):573-83.
- Boschmann M, Steiniger J, Franke G, Birkenfeld AL, Luft FC, Jordan J. Water drinking induces thermogenesis through osmosensitive mechanisms. J Clin Endocrinol Metab. 2007;92(8):3334-7.
- May M, Jordan J. The osmopressor response to water drinking. Am J Physiol Regul Integr Comp Physiol. 2011;300(1):R40-6.
- Tank J, Schroeder C, Stoffels M, et al. Pressor effect of water drinking in tetraplegic patients may be a spinal reflex. Hypertension. 2003;41(6):1234-9.
- May M, Gueler F, Barg-Hock H, et al. Liver afferents contribute to water drinking-induced sympathetic activation in human subjects: a clinical trial. PLoS ONE. 2011;6(10):e25898.
- Durie B. Senses special: doors of perception. New Sci. 2005;2484.
- Madjd A, Taylor MA, Delavari A, Malekzadeh R, MacDonald IA, Farshchi HR. Effects on weight loss in adults of replacing diet beverages with water during a hypoenergetic diet: a randomized, 24-wk clinical trial. Am J Clin Nutr. 2015;102(6):1305-12.
- Madjd A, Taylor MA, Delavari A, Malekzadeh R, MacDonald IA, Farshchi HR. Beneficial effects of replacing diet beverages with water on type 2 diabetic obese women following a hypo-energetic diet: a randomized, 24-week clinical trial. Diabetes Obes Metab. 2017;19(1):125-32.
- Dubnov-Raz G, Constantini NW, Yariv H, Nice S, Shapira N. Influence of water drinking on resting energy expenditure in overweight children. Int J Obes (Lond). 2011;35(10):1295-300.
- Maughan RJ, Watson P, Cordery PA, et al. A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index. Am J Clin Nutr. 2016;103(3):717-23.
- Wong KV. Temperature of food and drink intake matters. J Energy Resour Technol. 2016;138(5):054701.
- Bradley TH, Melby CL. Discussion: “Temperature of Food and Drink Intake Matters” (Wong KV, 2016, ASME J. Energy Resour. Technol., 138(5), p. 054701). J Energy Resour Technol. 2017;139(1):015501-1-2.
- Weiner BC, Weiner AC. The ice diet. Ann Intern Med. 2010;153(4):279.
- Kocełak P, Zak-Gołąb A, Rzemieniuk A, et al. The influence of oral water load on energy expenditure and sympatho-vagal balance in obese and normal weight women. Arch Med Sci. 2012;8(6):1003-8.
- Girona M, Grasser EK, Dulloo AG, Montani JP. Cardiovascular and metabolic responses to tap water ingestion in young humans: does the water temperature matter? Acta Physiol (Oxf). 2014;211(2):358-70.
Video production by Glass Entertainment
Motion graphics by Avocado Video
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Title
Friday Favorites: Optimizing Water Intake to Lose Weight
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
I mentioned my Evidence-Based Weight Loss talk.
Too good to be true? No. For more on water and weight loss, check out
- How to Get the Weight Loss Benefits of Ephedra Without the Risks
- The Effect of Drinking Water on Adrenal Hormones
- What Is the Safest Metabolism Booster?
The original video aired on October 14, 2020.
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