#122 How to Lose 10 Pounds with Water Preloading

How to Lose 10 Pounds with Water Preloading

“I just can’t seem to lose any weight,” Holly said at her last cardiology clinic visit.

“Are you drinking enough water?” I asked.

“I’m lucky if I can drink a glass or two of water through the day,” she replied.

Could water preloading be the secret for Holly to overcome her weight loss challenge?  In this article I share the new science behind water preloading and how it can help you to maintain a healthy weight for your heart.

What is Water Preloading?

Water preloading is really just the process of hydrating prior to every meal. Water preloading may help with weight loss because it stretches the stomach.  This mechanical stretching of the stomach shuts down ghrelin release.  With the hunger hormone ghrelin suppressed you will be less likely to overeat with your meal.

What is the Science Behind Water Preloading?

While many people have intuitively known that hydrating before a meal helps them to control their appetite, until recently there were no solid scientific data supporting this practice.  Fortunately, the study has now been done.  In this well-designed scientific study, Dr. Helen Parretti and colleagues from University of Birmingham showed effortless and significant weight loss with the simple act of water preloading.

To come to this conclusion, researchers enrolled 84 obese people and then randomly divided them into two groups.  The water preloading group was told to drink 500 mL, or 2 cups of water, within 30 minutes prior to eating each meal.  In contrast, the control group was told to imagine that their stomach was full prior to eating.  Interestingly, these study participants had no idea why they were doing what they were told to do.

Without even trying to lose weight, the water preloading group had lost an average of 5.3 pounds (2.4 kg) whereas the imagine your stomach is full group lost a mere 2.6 pounds (1.2 kg).  The results are even more impressive if you just look at the results of the people who actually did what they were supposed to do in this study.  Specifically, those who were 100% faithful in water preloading before each meal lost 9.5 pounds (4.3 kg)!  Equally impressive was that 27% of the water preloading group were able to lose enough weight to get down to their target body weight from water preloading alone.

Thin People Drink More Water

A separate line of evidence in support of water preloading is that there have now been many studies which have shown that fit people tend to drink more water.  Indeed, one study showed that water drinkers, on average, consumed 194 less calories each day.

It is unclear as to why fit people drink more water.  It is possible that by drinking water they are not drinking sugary or diet drinks.  Alternatively, drinking water may be allowing them to control their appetites.  Equally possible is that fit people drink water for cultural reasons as that is what healthy people tend to do.

Should You Try Water Preloading?

Given than about half of all Americans drink less than 4 cups of water each day, the simple answer would be “yes,” for most people.  Interestingly, in this report from the CDC, the same people who don’t drink enough water are also the same people who choose unhealthy foods.

The water preloading protocol of this study resulted in just 6 cups of water in a day.  This is still less than the 8 cups of water recommended by many healthcare providers.

For 99% of the population, there is little downside in drinking 2 cups of water before each meal.  Even if you don’t lose weight, if you are like most water deprived Americans, then drinking more water will probably result in other health benefits.

Will water preloading work for everyone?  Probably not.  However, if the results of this small study are true, then water preloading could result in a quick 10 pound weight loss over the next 3 months for you.

I must confess that since reviewing this study I have been very diligent in water preloading before each meal.  Whether it is a placebo effect or not, I have noticed that I don’t need to eat as much food to feel full.  Placebo effect or not, it is nice not feeling as hungry through certain parts of the day.

Who Shouldn’t Do Water Preloading?

If you are considering water preloading, and you do not feel well or are being treated for any medical condition, you should speak with your physician first.  For example, 500 mL of water prior to each meal is enough fluid to cause someone with heart failure to quickly become short of breath from fluid retention.

What has been your experience with water preloading?  Please leave your comments below for our community.

Disclaimer Policy: This website is intended to give general information and does not provide medical advice. This website does not create a doctor-patient relationship between you and Dr. John Day. If you have a medical problem, immediately contact your healthcare provider. Information on this website is not intended to diagnose or treat any condition. Dr. John Day is not responsible for any losses, damages or claims that may result from your medical decisions.

  1. I just read this article and I am overweight, I want to give a try and I will report to you in few weeks to see the results, I am excited about this.

    • Hi Glenn,

      Thanks for reading. Make sure your physician is aware as some conditions, like congestive heart failure, kidney disease, hyponatremia, etc. could all be made worse by significantly increasing water intake. If it is safe for you to water preload, please let me know if it works for you!



  2. Thanks for the awesome podcast. What I find interesting about this is that conventional wisdom says not to drink too close to meals. I drink 2 litres a day but I space it out thru the day and try to wait at least 30 mins and often a lot longer before eating. I going to try switching my routine to drink 2’glasses at a time 30 mins per meals. I have a little extra weight I gained around the belly post menopause so I hope this helps. Those extra few kg are very stubborn! They appeared rapidly and are stuck around my waist. For the rest of my life I have had an hour glass and any weight gain was even rather than this horrid visceral belly fat!!!

    • Hi Tania,

      Thank you so much for listening to my podcast! You are absolutely correct, conventional wisdom is not to drink too much just before or during a meal for fear of affecting digestion or nutrient absorption.

      As you pointed out, this protocol is designed to get the water preloading 30 minutes prior to each meal. Hopefully, this 30 minutes allows for most of this water to be absorbed before the meal hits the stomach.

      Since posting this article, I have been faithfully trying this approach. It is hard to say if it is a placebo effect or real but my appetite really does seems to be under better control at meals.


      • It’s inky been a couple of days but it does feel like it’s helping me too. Of course, the emotional eating and habits linger and I eyed the chocolates at the supermarket with intent.

  3. I lost over 25 lbs in about 10 weeks, just by starting a daily exercise regime. I drank at least 2 cups of water about 15-20 mins before exercising and then another cup after. When I was able to do 2 sets, I repeated that process with the 2nd set. I have lowered my glucose levels but so far, my A-fib condition has not changed. I’m hoping to spontaneously restart a regular heartbeat, since there are reports of that happening, without special treatment, like ablation, shock, etc. Shocking is not suggested for diabetics anyway, due to the high incidence of recurrence.
    I try to follow ALL your advice, Dr. Day – in my book, you’re a saint, for giving good accurate medical and nutritional advice for free. I really can’t thank you enough, for the hope and incentive you’ve given me. I truly thank God for you, for the knowledge you share and if there’s anything I can do for you, please don’t hesitate to contact me.

    • Hi Rich,

      This is a great success story! As you know, the studies suggest that about half of all atrial fibrillation patients can go into remission with lifestyle changes and weight loss. Even if you are not part of this 50%, the studies also report that you will be more likely to respond to therapy.

      Thank you so much for your kind words! Keep up the good work!


  4. I have a friend in Florida who was heavy ever since he was a child. Unfortunately he was made fun of and even ostracized by the other children he knew…just because he was round and the others were lean. As a high school student, he decided he was going to only drink water. Some people had a hard time recognizing him without his signature “Big Gulp”. He not only lost weight with his new water habit, but has kept it off for years and has passed on this good habit to his children…who are also trim.