diets · fitness

The newest weight-loss science we don’t need and can’t use

What do we want?

Weight-loss with net gain of lean muscle mass!

When do we want it?

Now! (or within the course of a grueling four-week study that leaves us starving and food-obsessed)

Okay, that’s not very catchy.

But just yesterday the results of a new study came out, courtesy of the American Journal of Clinical Nutrition and authors Longland et al. comparing the results of higher vs. lower protein diets (plus rigorous exercise) on weight loss and lean muscle mass.  The popular fitness press and protein-supplement manufacturers couldn’t be more pleased, as they trumpet the results, saying “Losing fat while gaining muscle:  it’s possible with the right diet!”

A more measured description of the study is offered by science writer Gretchen Reynolds in the New York Times.

…the researchers rounded up 40 overweight young men who were willing to commit to an intensive weight-loss program and divided them in half.

All of the young men began a diet in which their daily calories were cut by about 40 percent (compared to what they needed to maintain weight). But for half of them, this consisted of about 15 percent protein, 35 percent fat and 50 percent carbohydrates.

The other 20 volunteers began a diet that mimicked that of the first group, except that theirs swapped the protein and fat ratios, so that 35 percent of their calories came from protein and 15 percent from fat…

All of the men also began a grueling workout routine. Six days a week they reported to the exercise lab and completed a strenuous full-body weight training circuit, high-intensity intervals, or a series of explosive jumps and other exercises known as plyometric training.

The routine had succeeded in incinerating pounds from all of the participants. The men in both groups weighed about 11 or 12 pounds less, on average.

But it was the composition of that weight loss that differed. Unlike most people on low-calorie diets, the men on the high-protein regimen had actually gained muscle during the month, as much as three pounds of it. So in these men, almost all of the 11 or 12 pounds they had lost over all had been fat.

Here’s the most interesting part of the study, though:

The diet and exercise routine continued for four weeks, by the end of which time, “those guys were done,” said Stuart Phillips, who holds a research chair in skeletal muscle health at McMaster University and oversaw the study. “All they could talk about was food.”

Of course they would.  They were starved for a month on a very low fat diet while made to exercise vigorously.  The study doesn’t say anything about follow up.  My guess is that much of that weight loss disappeared rather quickly in the stampede to the local Dunkin Donuts. This should probably dampen our enthusiasm for these results, to say the least.


Let’s take a moment to look at who this research targets.  The participants were young men, ages 18–30.  The selection criteria for the study limited them also to BMIs under 27 and no more than 15% body fat.  No women were included in the study.  However,

They  [the researchers] plan, too, to study female volunteers and play around with the diets’ composition, to establish definitively that it is extra protein and not reduced fat that promotes muscle gains.

Oh, good.

More seriously, recent obesity research by David Ludwig, suggests that low-fat diets provoke hunger, triggering overeating.  There’s a nice op-ed here outlining some of his recent work.  He also has a recent diet book based on years of such research.  And Ludwig isn’t the only one paying attention to hunger.  Biologist Amanda Salis has also written a diet book based on her research that targets what she calls “the famine reaction”, which is a complex metabolic reaction to calorie (and fat) deprivation (full disclosure: I’m collaborating on a diet study with Salis and other colleagues now). a 40% calorie reduction diet is exactly the sort of plan that, according to Salis’ research, would also provoke extreme hunger with a risk of binge eating.

Of course, the researchers for this study know that this program isn’t designed for long-term use; not even the participants had any interest in continuing:

Of course, by the end of the month, none of the men wished to continue. This type of extreme calorie cutting combined with intense exercise “is not a sustainable program in the long term,” Dr. Phillips said. “It’s more a kind of boot camp,” he said, manageable in the short term by people who are very committed and generally very healthy.

But wait a minute:  the actual participants, who agreed to be enrolled in the study, who were young men under 30 with BMIs under 27, good base cardio fitness, were all ready to head for the hills (or rather, the nearest McDonalds drive-thru) the second the study finished.  This suggests that such a program is “manageable in the short term” by no one, ever.


This is simply not the kind of eating and activity research that is helpful for managing our own lives.  It’s 1) very unpleasant; 2) not sustainable at all; 3) not clearly applicable to almost all of the population; 4) potentially harmful in terms of provoking subsequent uncontrolled eating in response to deprivation.

So if we need a protest mantra, here’s one I would prefer:



12 thoughts on “The newest weight-loss science we don’t need and can’t use

  1. Also, these ‘overweight’ guys had BMIs under 27? That’s a seriously narrow BMI window they have there! Doesn’t ‘overweight’ start at 25.5? Talk about ungeneralizable data!

    1. Thanks, Rebecca, and you’re right– 25 or so is the line for “overweight”, but: 1) these guys had <15% body fat, and depending on what the avg is, 27 might be perfect for them (I can't access the original article, as it's not in my library's database yet). And of course that line got moved from 27ish to 25ish (for reasons, but still). This is ungeneralizable, disingenuous, and potentially harmful. blech.

  2. I love how studies like this that use only fit young males as participants tout the results as applicable to others. Call me when you do an actual study on women, nutrition scientists. Preferably over 30 (age and BMI).

  3. I did this type of diet, a protein sparing modified fast, a few years ago.
    I did not regain the weight, but I did become afraid of food and obsessed with carbs.

    I will admit I have some strong OCD tendencies. I know others who used this type of diet and phased off successfully. But, if you are like me, and inclined to disordered eating, it is a doorway to a lot of mental anguish.

  4. think that the problem with these kinds of high impact diets is that they alter the chemistry of the body and also of the brain. That’s why they are Dangerous.

  5. Excellent post, Catherine. I too want more tortillas when I order fajitas! And more salsa and more guacamole, hold the cheese please.

  6. When eating causes some sustained mental anguish/worry over several weeks/months and is no longer enjoyable, then there is something fundamentally wrong with how a particular diet is conceived/followed.

    Eating healthier for some people means finding healthier foods that they may initially be unaware of, broadening your palate (not limiting it) to more diverse cuisines that offer more healthier options, more cooking methods (that are healthier), breaking long term habits (eating meals at restaurants several times per week)… it isn’t just about “calories’, specific nutrients, etc. It is about making TIME investment for yourself about how you eat, when and what you eat. But not get paranoid about making the change.

    I think this is what some of these boot camp diets cause: paranoia and hyperalertness about food. A terrible way to live daily life.

    1. You said it, Jean! And thank goodness we have alternative models here to share with each other.

  7. Catherine, I love your posts and I think that this is a great critique of boot-camp-style weight-loss plans – but I don’t think it’s a fair representation of what this study was looking at (disclaimer: I also can only see the abstract). The study was a proof-of-principle trial looking at how varying protein intake affects weight loss, and found interesting results in the composition of the weight lost. The big energy deficit is necessary to create statistically meaningful (and comparable) weight loss in a short enough time period to get decent participant compliance. The single-gender focus is also necessary for statistical reasons, and weight variations in women due to menstrual cycles is probably the main reason the authors chose to study men during such a short study. This is the nature of scientific progress, frustrating as it is.

    (I also think it’s interesting to note that the “low protein” group still consumed about 1.5 times the CDN base recommendation of 0.8g/kg/day, or about equal to the athlete recommendation. So not low at all, but just the other group’s intake was very high)

    There’s so much to criticize in this industry, but this actually looks like some solid science to me, interesting for athletes (like Sam! And like myself) interested in losing fat/weight without compromising muscle performance.

    1. HI Courtney– thanks for the thoughtful reply. Yes, you are right that this is a proof-of-principle interesting result from a narrow scientific perspective. It’s not, however, a particularly applicable one, given that there was no followup, a small non-representative sample group, and participant compliance was barely sustainable during the 4-week trial period.

      But what is more worrying is that narrow studies like these get used (by press, sports and fitness sites, the general public and even other scientists– who should know better) as fodder for the utterly specious claim that rapid weight loss and muscle mass gain is possible to attain (presumably to sustain for longer than say, a few weeks).

      Scientific progress is shaped by all sorts of constraints, and yes, it is frustrating. I think, however, that it’s important to think about an important aim of science– improving human flourishing– and focus as best we can to spend our scarce resources toward that goal. We can’t know ahead of time what we can learn, and we’ve been surprised. But I don’t think this study taught us much that was useful for general health and fitness, and it is already being used in ways that may harm the general public’s health by encouraging people to engage in extreme diet and exercise, or blaming them because they don’t do so.

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