Did you know that there’s a theory that if you drink water with or before your meal you’ll gain weight because it makes your stomach bigger? And another theory suggests that if you drink water with or before your meal, that you’ll affect digestion by turning your food into a grey mush and that will cause weight gain. And one that suggests if you drink water with or before your meal, you’ll negatively alter your stomach acidity. Some of these theories are easy to disprove, others may hold water (I couldn’t help myself). Hint about the mush one though: the process of turning your food into mush is called digestion. There are numerous studies that have shown drinking water right before eating helps with weight loss, not weight gain:
  • This study found those who drank water before eating lost an extra 2 kg over 12 weeks.
  • In this one, participants either drank water or drank nothing and imagined their stomachs being full before their meal. Over 12 weeks, those who drank water lost on average 2.9 pounds more than the visualizers.
  • This study looked at how much food people ate during a meal relative to selecting one of five beverages or no beverage. It showed no difference between people who drank water, diet cola, or nothing; and showed those who drank caloric beverages (cola, orange juice, or 1% milk) consumed on average 104 calories more.
water glass joe plockl noncommercial flickr In summary about pre/during meal water consumption contributing to weight gain: Two studies reviewed showed weight loss, and one study showed no difference. I recognize that three studies is not exhaustive, but I did scan search results and was unable to find any studies suggesting water would contribute to weight gain. If you know of any, please send me an email as I want to be sure I’m sharing accurate information. Next theory: Does water disrupt your stomach pH? There is a theory that if you drink water with your meal or within an hour before or after, you’ll negatively affect the pH level (acidity) of your stomach, which will impede digestion and lead to weight gain. This study supports this contention – sort of. It notes that after drinking water, stomach pH increased to higher than 4 (normal varies from person to person but is about 2) within one minute. But it was back to normal within 3 minutes. Is that enough to worry about? I will suggest that 3 minutes of elevated pH is not something to worry about. If you are worried about your stomach pH affecting your digestion, then wait 3 minutes after drinking water before eating your meal. Don’t drink cold water? Still another theory is that you shouldn’t drink cold water because it slows digestion. This study had scientists place sensors in the stomachs of participants (through their noses) combined with gamma cameras (not in the stomach) to identify when orange juice at 4 deg Celsius, 37 deg C, and 50 deg C left the stomach. They also looked at temperature readings in the stomach. It seems there is something to this temperature theory. The cold juice did take longer to digest, but within 10 minutes, there was no difference in the amount of liquid in the stomach between the cold and control juice. It also took 30 minutes for the stomach to return to normal temperature after ingestion of the cold juice versus 20 minutes for the warm juice. Does it matter to you if it will take your stomach an extra 10 minutes to digest and return to normal temperature? I would suggest that for most people, most of the time, this is not an issue, and won’t be noticeable. If you are someone who has digestive challenges, then that 10 minutes of extra digestion and of extra time for your stomach to return to normal temperature might be relevant, in which case warm water is probably a better choice. What about athletic competition? Would the extra digestion time for cold water get in the way of performance? Maybe. But it may also affect hydration. So I looked up whether temperature of water consumed has an affect on the body’s ability to rehydrate. Unfortunately I could not find any relevant studies on that, but I did find this study that showed individuals exercising in heat (40 C) drank less when consuming warm water (40 C) than they did when consuming cool water (15 C), resulting in a greater loss of fluid. So, the question is really whether extra digestion time for cold water would affect performance more or less than reduced water intake with warm water. I will stop the spiral of investigation at this point partly for time, and partly because I’m extrapolating from single studies, which isn’t good scientific practice. Instead I will leave you to decide whether you have seen adequate evidence to decide whether it matters if you drink your water warm or cold, or whether the topic is interesting enough that you decide to research it further. Isn’t science fun? Elsbeth Vaino, B.Sc., was an engineer before becoming a personal trainer, and well, that probably isn’t surprising, given the high geek quotient in this post.

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  1. “My question is, is it worth going for?”

    In a word, no.

    If you follow it, you’ll likely lose weight – not because of the cleanse, but because you’ll be on an ultra-low calorie diet while on it. And because you’ll be restricting carbohydrates so much, most of the weight you’ll lose will be water. As soon as you stop, the water weight will come back.

    Here’s a post I wrote about the science behind cleanses: https://elsbethvaino.com/2013/07/should-you-do-a-cleanse-part-2/

  2. Thanks for this article. We all know that workout and a good diet is best for remaining healthy and fit. And water has a vital role in weight loss. But I have read an article which promises that you can lose weight by exercising less. I know it sounds crazy but they show a new cleansing program that detoxifies the body and sheds pounds quickly and safely. It permits virtually anyone to lose 14lbs in exactly a matter of weeks. Just want all of your thoughts about it.
    My question is, is it worth going for?

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