Can dehydration really lower our resting metabolic rate?

Question

Ok, that's it. I've read about how dehydration can "slow down" our metabolism one time too many, so I decided to conduct my own research - and find out once and for all, whether or not that's just another one of the many weight loss myths in existence.

If you do a quick search on Google, you can find plenty of weight loss articles explaining how proper hydration of the body is a must - which is something I definitely agree with for health reasons - but when it comes to the effect of dehydration on our energy expenditure, I have yet to find any scientific proof that dehydration does indeed cause our bodies to start burning less calories.

I will keep searching for conclusive evidence, but in the meanwhile, I'd like to ask all the incredibly smart people here if one of you already knows the answer to my burning question (pun intended)?

Answer 1

Dehydration has a negative effect on metabolic rate in skeletal muscular metabolism in that it hinders metabolic efficiency with strain and heat.

See this link for the full article. And this one for a research publication.

"Based on three previous studies that found dehydration depressed metabolic rate, a team of graduate students at the University of Utah undertook a study to determine how hydration affected resting metabolism. E. Wayne Askew, director of the Division of Foods and Nutrition at the university’s College of Medicine, led the research study. Research subjects were divided into three groups: The first group received four 8-ounce glasses of water daily, the second got eight 8-ounce glasses and the third got 12 8-ounce glasses per day. Test subjects -- all of whom were measured at rest -- who received eight or 12 glasses of water daily burned calories at an accelerated rate, compared to those who were not fully hydrated."

As a follow-up to their 2003 findings that drinking 500 milliliters of water quickly induced thermogenesis -- the calorie-burning stage of metabolism -- in men and women of normal weight, German researchers repeated their study with patients who were overweight or obese but otherwise healthy. Their findings, published in the August 2007 issue of “The Journal of Clinical Endocrinology & Metabolism,” showed that test subjects experienced an average 24 percent increase in energy expenditure within one hour of drinking the water.

Also see this research on Mechanisms of aerobic performance impairment with heat stress and dehydration

"Greater relative exercise intensity increases cardiovascular strain, which is a prominent mediator of rated perceived exertion. As a consequence, incremental or constant-rate exercise is more difficult to sustain (earlier fatigue) or requires a slowing of self-paced exercise to achieve a similar sensation of effort."