Drink a glass of water before meals, lose weight!

February 03, 2020

References: George Mason UJCEMEur Jr of NutritionJ of Amer Diet Assoc
Doesn't this idea ring true with you? Drink a glass of water, lose weight! The research is pretty simple and pretty elegant. (And pretty small group). Sixteen young adults (6 men, 10 women, average age 29) drank 250 or 500 mls of water and then were tested over the following 90 minutes for resting metabolic rate. They had a statistically significant increase in resting metabolic rate, burning an EXTRA 50 calories, which was mostly fat calories. 500 ml did more than 250. 
That's not a lot of calories, but that can add up. If you do it every day, you've lost 5 pounds over a year. That's about what most of us gain every year. 
This study joins others on the same topic that have come to the same conclusion. This study from Canada and Germany concluded that water drinking had a 30% increased basal metabolic rate and would result in about 5.5 pounds a year of weight change. In men the water drinking increased fat mobilization through stimulation of beta-adrenoreceptors, but not in women. Women appeared to mobilize carb stores. 
Why does this happen? The authors conjecture that the measured increase in the sympathetic system might have something to do with the temperature of the water, and the metabolic cost of heating it up to body temperature. But after all their calculations, that would only account for 30% of the effect. Not enough. They did measure a change in blood concentration (osmolality). It got lower, as you would expect.

I suspect there are a variety of other things that happen. With lower blood concentration and a larger volume of blood, for 45 minutes, your blood can flow a little easier so cells can wake up and start a new day. You got dehydrated overnight and everything is a little "sludgy" and slower. Or, you make cortisol in the morning and your cells get more of it with more blood flow and burn a teeny amount more energy. Heating up the water takes some of it. Your kidneys get to work a little more, your liver works a little more, your brain works a little more. Voila, more energy spent.

Now, add this effect to water's impact on appetite and water turns out to be a pretty good drug. A study in the European Journal of Nutrition shows that folks who drink two glasses of water before a meal eat less. Again, these would young, normal-weight college men, but the effect was reproducible and real. Another study in obese folks found the same effect.

The total cost of drinking a glass of water each morning? Free! Do it! Drinking a glass before every meal? Well, must be three times as expensive - three times zero is......

WWW; What will work for me. I love this idea. So simple and so elegant. I don't want to have to get up at night and don't like the idea of drinking more water in the evening. But an extra big glass first thing in the morning? Not bad. Couple times a day? I can do this.

Pop Quiz

  1. What happens when you drink a glass of water before breakfast?   Answer: your REE, Resting Energy Expenditure, goes up for 90 minutes.
  2. How much energy do you burn?   Answer:  About 50 calories.
  3. What does that result in over a year:   Answer:  Five pounds
  4. 4. What about appetite and water before meals?   Answer:  Separate effect, but that too goes down.  
  5. What's the cost of drinking that water?  Answer: If you have to think too long on this one, go back to Home and start again.  

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