Saturday, July 12, 2014

Weight Loss Myth Confirmed: Drinking 1.5L Extra-Water a Day Helps Young Women Shed Body Fat - 2.8lbs in 8 Wks!

"Where bro- and pro.science meet!" could have been the motto of the Indian researchers who probed the "drink water to lose weight myth" in their latest study.
I am not sure if you can actually call this "broscience", 'cause almost everyone believes in the weight loss magic of drinking plenty of water. I guess for it to become broscience, it does yet have to have that "sciency" tinge of being brought about by an increase in thermogenesis. That's in contrast to the average housewife myth, where the "experts" provide more intuitive explanations such as: "It fills you up!"

Apropos housewifes! I can't tell for sure, but it's certainly not unlikely that overweight female subjects of a recent study (Vij. 2014) from the Seth Gordhandas Sunderdas Medical College and King Edward Memorial Hospital in Mumbai were actually housewifes - probably not.
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In the end, the occupation state of these ladies, whose mean body weight at the beginning of the study was 65.86kg (BMI 26.7) doesn't really matter, anyway.

What does matter, though, is that the 50 young ladies (age 19-29.9y) were - in European or US terms - comparably lean, when they were told to increase their water intake by 1.5 L, over and above their usual daily water intake. To achieve this, 500 mL of water was consumed 30 min  before breakfast, lunch, and  dinner. 
Water warning: It may sound stupid, but too much of a good thing can easily be as bad as too little. This is not different for water! Adding 1.5l to a baseline water intake of <2l certainly isn't a problem. Drinking 15l per day to lose weight, on the other hand, would have you lose much more than body fat - in the long run, possibly even your life.
Why that's important? Well, if you weigh "only" ~130lbs and still manage to lose 2.8lbs in 8 weeks, that's quite significant considering the fact that the only thing you'd have to do to achieve that is drink 500ml of plain water before each meal, right?
Figure 1: Pre- and post value for skinfold thickness (mm) and appetite scores (Vij. 2014)
Well, if we take a closer look at the data in Figure 1, it gets even better! Although we don't have DEXA data for the lean and fat mass data, the reduction in the sum of skinfold thickness and the significant reductions in appetite sore speak in favor of this simple, yet obviously effective approach to weight loss.
Cannot drink even more water? Try alternate day fasting | learn more
And how does it work? Now that we've learned that this piece of housewife- / broscience stands the test of "real" science (the fact that the study didn't have a control group makes it difficult for me to use the word "science" in conjunction w/ the study at hand), we still have to find out, whether it's the housewife or the bro-hypothesis that explains this miraculous weight loss. The authors of the paper at hand, which has been published in the latest issue of the Journal of Natural Science, Biology and Medicine appear to vouch for the bros, but have to admit that "[t]he mechanism causing sympathetic activation with water is not fully understood" (Vij. 2014).  The fact that it does not work in tetraplegic patients does yet suggest a spinal mechanism.

What is certain, though, is the fact that it's not the energy that's necessary to heat the water. The "water weight loss trick" works minimally better with cold water, but the difference is way smaller than it'd have to be if we used the extra energy only to heat the water (Boschmann. 2007). The contemporarily available evidence does in fact rather point towards osmosensitive sympathetic nerve activity... but let's be honest: Do we care, if it works? No, but you could achieve way more if you skipped on drinking extra water and followed the 9 rules of sensible weight loss.
References:
  • Boschmann, Michael, et al. "Water drinking induces thermogenesis through osmosensitive mechanisms." The Journal of Clinical Endocrinology & Metabolism 92.8 (2007): 3334-3337.
  • Vij, V. K., and A. S. Joshi. "Effect of excessive water intake on body weight, body mass index, body fat, and appetite of overweight female participants." Journal of Natural Science, Biology and Medicine 5.2 (2014): 340.