Bill:

That's actually a rarely documented confounding variable in many diet studies: what were the subjects eating before the intervention? 

Investigators will take pains to sort by age, weight, BMI, medical status, and so on -- but they rarely account for the variation in human diets.

eddie:

Thank you!  Yes, "What were the subjects eating before?" seems like a very common-sense question to ask...and you're reminding me of Chris Masterjohn's classic article New Study Shows that Lying About Your Hamburger Intake Prevents Disease and Death When You Eat a Low-Carb Diet High in Carbohydrates.

Bill:

Nutrient partitioning is a whole new subject...and yes, protein strongly affects it.  Even the studies that show no absolute weight advantage for high-protein diets show improved body composition.

ItsTheWooo:

It's surprising how much lean mass is lost on typical hypocaloric diets.  Here's an interesting study showing that, for normal weight women, losing ~0.5kg/week preserves lean mass, whereas losing 1kg/week is catabolic and tanks hormone levels.

J Int Soc Sports Nutr. 2010 Jan 25;7(1):4. doi: 10.1186/1550-2783-7-4.
Moderate energy restriction with high protein diet results in healthier outcome in women.
Mero AA, Huovinen H, Matintupa O, Hulmi JJ, Puurtinen R, Hohtari H, Karila TA.

Given that, just imagine the results from your average "cleanse" (read: zero-protein crash diet).  Repeat this cycle a few times and you, too, can be skinny-fat!

JS

eddie:

Actually, counter movement jump distance increased more in the 0.5kg/wk group (see Table 1), though not significantly...I have no idea why the text of the study claims otherwise.  I suspect the increase in endurance is because starvation diets (~1000 kcal) are a high-fat diet of one's own adipose tissue, and consequently require high levels of fat oxidation, which Type 1 muscle fibers are much better at than Type II fibers.  But this is speculation.

Another interesting part is in the "General Mood" section:

"In 0.5 KG, 57% of the subjects (n = 4/7 = 4 subjects from 7 subjects) reported that they had more alertness in work/studying and training during the weight loss regimen. Similarly in 1.0 KG, 44% of the subjects (n = 3/8) reported that they had more alertness in school and only 25% reported that they had more alertness during training. Furthermore in 1.0 KG, 50% of the subjects (n = 4/8) reported that they had felt less alertness during training when no one in 0.5 KG gave such an answer (n = 0/7). The subjects in 0.5 KG also reported better general mood and no one from this group reported any kind of anxiety when 37.5% (n = 3/8) in 1.0 KG reported that they were more anxious and felt more tired than usual."

Also, I need to amend my statement: the 1.0kg/wk group did not lose more lean mass in the first four weeks (although there is no indication that the authors measured it...: what the authors say is that their hormonal environment is more catabolic, so that they'd expect to lose more lean mass as the diets continue.

Also, I noticed that cortisol was up 15% in the 1.0kg/wk group, though the authors called that "no difference".

Also, I noticed that the authors claim "Metabolic acidosis has been linked to muscle wasting in obese subjects who were acidotic due to weight reduction diets [19,20]. The correction of the acidosis has been shown to reverse the muscle wasting in that condition [21,22]."  However, neither reference 21 or 22 supports that contention: they show only that bicarbonate supplementation reduces urinary nitrogen excretion in either patients with renal failure in the short term (1 week), or in patients on a 3-week PSMF (this study also confuses ketoacidosis with ketosis), which is a long way from proving muscle wasting.

This sort of sloppy science is why I don't bombard people with 15+ citations per article: there's a lot of shecky work out there, and if someone gives me that many cites for a blog post, I'm calling BS on them actually having read them, let alone verified that they support the hypothesis!

Paul N:

Yes, protein is a daily essential...and like all essential macro- and micro-nutrients, just because you're eating less food doesn't mean your body's requirement magically decreases!  So yes, it's best to measure your target protein intake in grams, rather than as a percentage of "calories".

And yes, I encourage both men and women to play like predators, not "exercise" like prey.  Your body quickly adapts to the low-level steady-state demand of "cardio", often leaving you fat -- whereas adaptation to occasional intense effort will cause your body to divert more resources towards building strength ("nutrient partitioning"). 

Remember that muscle mass is counterproductive to long-distance running: note the relentlessly tall and skinny build of the Kalenjin, who win most marathons these days.  And as I point out in this article, male ultra-endurance running champions carry an average of 17% bodyfat -- nowhere near the coveted "six-pack".  And there is plenty of evidence, scientific and anecdotal, that long-distance running is not healthy!

Berneck:

No, I haven't yet finished that particular series...if I've written a followup, I generally place the link to the next part at the end of the article.

JS

Dave:

The data we have (as opposed to speculation or second-hand stories) shows that persistence hunting only works with a very specific animal — old male kudu — and that the speed of a successful persistence hunt is 6.2-6.6 km/h (3.9-4.1 MPH). (Source.)

That's a fast walk, not a "run"…

…and the fact that no one has ever been witnessed to successfully ran down any other animal (despite years of trying, e.g. "Running After Antelope") should prove to us that neither long-distance running nor persistence hunting is the driving feature of human evolution it's been claimed to be. 

I need to write an article about this misconception sometime!

JS

tatertot:

You're correct: fiber and "resistant starch" (which, strangely, doesn't seem to be counted as fiber in nutrition labels) are counted at 4 kcal/gram, which overestimates available energy by at least a factor of 2.

One must also account for the energy of digestion, which tends to be high in the case of unprocessed foods high in RS and fiber.  Paul Jaminet contends that, as a result, green vegetables actually have negative "calories"...and I believe the evidence supports him.

JS

Tonto:

Thank you for sharing that...and yes, it absolutely fits into the discussion! 

"Larger game was also chased in this manner using a series of stone fences and relay runners strategically positioned"...that confirms what I've read from other sources, which is that Native Americans didn't practice straight all-day persistence hunting: they herded wild animals into natural terrain features, usually (as you said) with teams of runners, and constructed very long and elaborate fences and corrals where the terrain didn't provide them.

I review two books on the subject in this article ("Survival by Hunting" and "Imagining Head-Smashed-In"), and I'm very interested in your opinion if you choose to read them.

That's interesting that you were able to catch small animals with a few minutes of sprinting and the smarts to keep them away from their burrows!  Having grown up in suburbs, I never had those types of opportunities...though unlike the city kids, I at least got to climb trees, scramble down ravines, etc.

I do note, however, that none of these activities qualifies as "persistence hunting", let alone long-distance steady-state cardio.

Dave:

It's possible to get thin by losing muscle mass...and from the studies I've read, most diets that aren't "high protein" result in significant loss of muscle mass as well as fat mass.  As mentioned above, our protein requirements don't decrease just because we're eating less food, so staying at 15% protein when dieting is likely to leave us protein-deficient and losing lean mass.

Additionally, endurance exercise is catabolic, and requires a higher protein intake to preserve muscle mass than even strength training!

Result: vegan diet + jogging = skinny-fat.

neal:

Thank you for the links!  The exercise article seems to agree with Mark Sisson's approach: lots of walking around and occasional sprints or heavy lifting, as opposed to "cardio".  And I agree that examples from agriculturalists aren't relevant to our evolutionary context, either.