33002Re: [John Muir Trail] 0.4 lb weight loss per day leads to loss of strength and feeling less energetic in lean, active young men
- Jul 12, 2013For what it's worth, I've been doing a bit of reading/research lately on sports nutrition (work project and personal interest). As far as I can tell, from sources that appear to be grounded in scientific literature, the per-kilogram protein needs for an athletic individual is somewhere between 1.2 and 1.7 grams. (For sedentary adults, the level appears closer to 0.8g.) Endurance athletes (JMT hikers) are likely skewed toward the higher end of this scale because they actually derive some of their energy for hiking from their protein intake, in addition to needing the protein for maintaining and building muscle mass, etc. Note that this is not a percentage of total daily calories. No matter if I'm burning 3000 or 5000 calories a day...my protein needs are darn near identical, which kind of makes sense. A person has only so much muscle mass to maintain.
Here's the thing (close your ears, Paleo devotees...you aren't going to want to hear this): while getting a minimum amount of protein is important for maintaining muscle mass, after a certain point your body simply can't use it, and needs to figure out what to do with it. Using protein for energy is a much less efficient process than using carbs for energy, and requires excretion of byproducts of metabolism (namely nitrogen) via the urine, which means increased risk of dehydration because all of that processing is going to require more water.
So, based on what I've read so far, when the time comes for me to hike the JMT (I'm still probably a couple of years out), I'd probably calculate my protein needs (~1.7 grams/kilo) and make sure I met that. And then I'd cram as many other calories into my bear can as I can, trying to stay as carb-heavy as possible (since that's the most efficient energy source from a metabolic standpoint). Since I'm fairly confident I could reach my protein intake in my meals and snacks, I'd skip the protein drink powder in favor of the carb-heavy sports drinks, hot cocoas, etc. And of course I'd try to keep my overall caloric deficit as minimal as possible.
So, there it is...my two cents. I reserve the right to alter my opinion as my research progresses. But some of the protein-heavy talk was making me a bit nervous and I wanted to get this off my chest. :)
P.S. For those interested, my primary reference so far for the above is "Advanced Sports Nutrition" by Dan Benardot (http://www.amazon.com/Advanced-Sports-Nutrition-2nd-Edition-Benardot/dp/1450401619) Nancy Clark says much of the same, but doesn't get into the biological/chemical details like Benardot does. An excerpt on protein intake from one of her books is here: http://www.humankinetics.com/mediasvr/marketingpdfs/clark/clark%20127-130.pdf)
--- In firstname.lastname@example.org, Roleigh Martin <roleigh@...> wrote:
> These subjects in my own research deprived their bodies of way too much fat
> and protein
> [image: Inline image 1]
> It would have been far more interesting if they had consumed about 30%
> protein, 30% fat, and 40% calories carbs, or at least 125g of protein a
> day. I think their level of exercise demanded the excess protein and hence
> caused their metabolism to consume their lean mass to get protein that way.
> Furthermore, depriving your body of adequate fat, minimizes the body's
> biochemical tendency to want to burn fat, at least from what I read.
> I definitely think they deprived themselves of adequate protein when doing
> that much exercise.
> Visit my Google Profile (lots of very interesting research
> On Sun, Jul 7, 2013 at 2:32 PM, John Ladd <johnladd@...> wrote:
> > **
> > Executive summary (since this is a long post):
> > Calorie deficit resulting in 0.4 lb weight loss per day leads to loss of
> > strenth (and endurance?) and feeling less energetic in lean, active young
> > (17-35) men over 3 weeks
> > Full post:
> > We tend to assume that our weight loss on trial is all body fat. But, even
> > in the obese individuals who are the subjects of most of the research on
> > calorie restriction (CR), about 25% of weight loss on CR diets will be lean
> > body mass (stuff other than bodyfat, including but not limited to muscle).
> > It is possible in the obese to minimize the loss of skeletal muscle by
> > including exercise (easy for us) and extra protein (not so easy for us).
> > Unfortunately, most of the diet studies are on individuals with lots of
> > spare body fat. For those of us with less to spare, muscle loss appears to
> > be more of a problem, if the small study summarized here ends up being
> > replicated by further research.
> > The lead author was affiliated with the V.A. but an Army researcher (form
> > Natick labs) participated, as did researchers from respected academic
> > institutions including Stanford, Amherst and US Berkeley. Natick has done
> > many studies on dietary needs of soldiers and is a quite respected
> > institution for research like this.
> > The study used lean young men (9 subjects, age 18-35, average weight 170#,
> > average 16% fat in bodyweight), all physically active. Subjects were
> > accepted into the study only if they needed at least 2700 calories per day
> > to maintain a stable body weight. They averaged 3245 in caloric needs per
> > day. Their average, calculated pre-diet Base Metabolism Rate (BMR) for age,
> > weight etc. was 1900 per day.
> > This suggests that the subjects were quite physically active, since the
> > ratio of of 1.7 between total caloric needs and BMR is about the same as I
> > use to calculate my food needs backpacking at 12 miles per day. The Harris-Benedict
> > Equation<http://www.bmi-calculator.net/bmr-calculator/harris-benedict-equation/>suggests that a 1.725 ratio between total caloric need and BMR is
> > equivalent to "hard exercise /sports 6-7 days per week".
> > Thus they are not untypical (except for age) from many of us.
> > Each subject was put on a diet that resulted in a 40% reduction in the
> > calories they needed to maintain a steady weight - this averaged a 1300 per
> > day calorie deficit. Significantly, this was accomplished entirely by
> > reducing fats and carbs. Protein levels were maintained very close to the
> > pre-CR baseline. The subjects maintained their usual activity levels.
> > They subjects, not surprisingly, lost an average of 8.4 # in the three
> > weeks of the study, or 0.4 lb per day. This is close to the oft-cited rule
> > of thumb that it takes a 3500 calorie deficit to cause 1# of weight loss.
> > (1300 calories x 21 days divided by 3500 = 7.8)
> > Many people would find this an acceptable weight loss on trail and many
> > who have reported back to this group say they have lost more (up to a lb
> > per day seems not all that uncommon)
> > The weight loss might sound like a benefit, but only 50% of the lost
> > weight in these active, lean individuals was in bodyfat (adipose tissue).
> > The other half of the weight loss was in lean body mass<http://en.wikipedia.org/wiki/Lean_body_mass>.
> > Negative nitrogen balance <http://en.wikipedia.org/wiki/Nitrogen_balance>was observed, indicating that the body was metabolizing its own protein
> > stores. Over 50% of lean body mass is skeletal muscle, though this does not
> > in itself necessarily indicate that 50% of the total loss came from
> > skeletal muscle, since the body can metabolize things in addition to fat
> > and muscle when it needs to pull calories out of the body. But it is a
> > reason for some concern.
> > Of greater concern: there was a 20% average loss in measured arm strength,
> > statistically significant at the 95% level. The arm strength measure was
> > the only one that isolated strength in the study.
> > On the plus side, aerobic capacity (VO2Max) was preserved.
> > An endurance measure declined modestly (6%) but in this small study did
> > not reach statistical significance.
> > One other performance measured actually improved across the 3 weeks of the
> > test, but the authors suggest that this more complicated test might have
> > shown improved results because the subject simply became more technically
> > proficient at the task, which stimulated loading shells into a field gun
> > (the research was financially supported by money from the DoD as well as
> > from the VA)
> > "Subjectively, participants reported no reduction in their activity
> > levels, but did report that they felt 'less energetic' during exercise of
> > long duration (such as soccer) towards the end of the caloric restriction
> > period."
> > This might be the best single article to read in considering a calorie
> > restricted diet on the trail. The study was small (only 9 subjects) but
> > appears to have been very thorough.
> > To me, it suggests that this level of caloric restriction (e.g.
> > corresponding to a weight loss of a bit under a 1/2 lb per day) is a bad
> > idea at least for those of us who are already pretty lean.
> > Citation:
> > Three weeks of caloric restriction alters protein metabolism in
> > normal-weight, young men
> > A. Brooks, Andrew R. Hoffman and Allen Cymerman Fulco, Steve R. Muza, Paul
> > B. Rock, Gregory C. Henderson, Michael A. Horning, George Anne L.
> > Friedlander, Barry Braun, Margaret Pollack, Jay R. MacDonald, Charles S.
> > Am J Physiol Endocrinol Metab 289:E446-E455, 2005. First Published 3 May
> > 2005;
> > Full copy available as a pdf
> > http://ajpendo.physiology.org/content/289/3/E446.full.pdf+html
> > John Curran Ladd
> > 1616 Castro Street
> > San Francisco, CA 94114-3707
> > 415-648-9279
- << Previous post in topic Next post in topic >>