The futility of selective nutrient deprivation

Matt Fitzgerald, who has written a slew of articles and books about endurance sports with a special focus on nutrition and is a 33-minute 10K runner himself, has a nice blog entry today about the tendency of people to approach weight loss in the mistaken belief that getting rid of a particular macronutrient is “the secret.”

Fat is the victim of an unfortunate name. It is all too easy to believe that eating fat makes a person fat. Indeed, for many years most diet experts believed that it did, and many do even today despite compelling evidence that eating a fairly high-fat diet is no more likely to cause overweight than eating a high-carbohydrate or high-protein diet. For example, in a 2002 review, entitled “The Influence of Dietary Composition on Energy Intake and Body Weight,” Roberts et al. noted that 1) fat calories as a percentage of total calories in the American diet have fallen over the preceding 20 years while overweight and obesity rates have increased drastically; 2) studies designed to determine whether people eat more calories when they eat more fat have generally concluded that they do so only when the energy-density of foods in not controlled, suggesting that energy-dense foods rather than fat per se are the cause of weight gain; and 3) studies investigating the effects of reduced fat intake on weight loss have shown that reduced fat intake results in very little weight loss when calories are not controlled, suggesting that it is an excess of calories in general rather than of fat in particular that causes weight gain.

People have been trying the selective-nutrient-deprivation things for at least 20 years now. When I was in college, fat was the enemy; there commenced a proliferation of products like Snackwells that were specifically created as fat-free goodies, and foods that had always been fat-free (e.g., pretzels), suddenly announced this on their packaging.
But America in general continued its tend toward bloatation, so in the late 1990’s, constructs such as the Atkins diet, which more or less demonized carbohydrates that didn’t grow in the ground and feature leaves, became vastly popular. A carbo-depletion diet is a great weapon for an entrepreneur because it works extremely well in the short term; as glycogen stores in liver and muscle are consumed, three grams of water are lost for every gram of glycogen burned, so no matter who you are and what you do, you’re going to lose 5-6 pounds off the bat by following an Atkins-style plan. That’s the “hook.” But once the honeymoon is over, people tend to experience fatigue and mood crashes if they severely restrict carbohydrates–and that’s just the sedentary ones. No sane athlete would ever attempt to stay on this failed bandwagon for long.
Protein is unlikely to ever become a target, because it’s almost impossible to eat such an excess of it in isolation that it can be fingered as any sort of culprit. Ever notice how thirsty you get after a steak or even a tuna sub? It takes a lot of water to break down protein, and there’s something uncomfortable about having too much circulating nitrogen, or something.
Anyway, the bottom line is that people are resistant to the unfortunate truth: If you want to lose weight, gimmicks and half-measures won’t get you there.
Matt notes that fat may actually have specific benefits, at least in runners:

[A] study from the University of Buffalo found that female runners who got 30 percent of their calories from fat were significantly less likely to get injured than those who ate less fat. It is not likely that the extra fat itself protected the less-often-injured runners, however. Rather, those who ate the least fat probably did not get enough total calories to meet their bodies’ needs.
Another line of research has shown that higher-fat diets increase fat oxidation during prolonged exercise and may thereby increase endurance. Researchers from New Zealand compared the effects of a 14-day high-carbohydrate diet, a 14-day high-fat diet, and an 11.5-day high-fat diet followed by a 2.5-day carbo-loading diet on fat oxidation and performance in a 15-minute cycling test and a 100-km cycling test. Performance in the 15-minute test was slightly better after the high-carb diet, but not to a statistically significant degree, while performance in the 100-km test was slightly better, but again not to a statistically significant degree, following the high-fat diet. Fat oxidation was significantly greater during the 100-km test following the high-fat diet.
Other studies have found that high-fat diets reduce performance in shorter time trials by reducing carbohydrate oxidation. However, recent research indicates that endurance athletes can have the best of both worlds by maintaining a habitual higher-fat diet in training and then switching to a high-carbohydrate diet before competition. Studies have shown that the high-fat diet adaptation of increased fat oxidation capacity persists through the carbohydrate loading period, which in turn ensures that carbohydrate oxidation capacity is not compromised in competition. A study from the University of Cape Town South Africa found that a 10-day, 65-percent fat diet followed by a three-day, 70-percent carbohydrate diet increased performance by 4.5 percent in a 20 km cycling time trial preceded by a glycogen depletion ride.

I once had a roommate whom I did not know before moving in with her. She knew I was a marathon runner, and on this basis decided I would exist on some kind of macrobiotic regimen and shun foods like pasta (which of course is a runner’s–and pauper’s–staple). She was hoping to get active herself and lose some weight, and later admitted she was counting on me to be a dietary role model. I would not advise anyone to do this, ever. People don’t become fast by playing around with their diets, or more specifically, by placing severe restrictions on certain items (“foods” such as straight warm vodka excepted). To wit:

It also bears noting on this topic that the typical endurance athlete gets 30 to 35 percent of his or her daily calories from fat–substantially more than the minimum. Indeed, even most elite American endurance athletes maintain relatively high-fat diets. The fact that our most gifted runners, cyclists, rowers, etcetera are routinely able to win national championships on a high-fat diet is the best possible proof that a high-fat diet is not inimical to endurance performance.
Based perhaps in part on this commonsense consideration, as well as on the relevant science, the American Dietetic Association and the American College of Sports Medicine now recommend that athletes get 20 to 35 percent of their calories from fat. Gone is the notion that the minimal adequate level of fat intake is also the optimal or even the maximum acceptable level of fat intake. It is now recognized that many athletes can perform equally well at a range of fat intake levels, and that some individual athletes may need to experiment before they find their personal “sweet spot” within that range.

Matt’s blog is always well researched and probably includes more actual science than this one does, so if you have any inclination at all toward running or endurance sports in general, consider bookmarking it.

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  1. #1 by natural cynic on May 11, 2009 - 2:44 pm

    The traditional subsistence diet of the Inuit is very low carb – fish and aquatic &/or terrestrial mammal with only small seasonal consumption of fruit – and they seem to have survived that way for thousands of years.
    And just about anybody can get along well without high glycemic index carbohydrates. It only takes some knowledge and a little more will-power. Ornish seems to have shown that.

  2. #2 by complex field on May 11, 2009 - 10:14 pm

    Of course, the Inuit probably have had 10Ky of selective pressures to allow the current population to subsist on their particular diet.

  3. #3 by complex field on May 11, 2009 - 10:14 pm

    Of course, the Inuit probably have had 10Ky of selective pressures to allow the current population to subsist on their particular diet.

  4. #4 by wybory sondaze demokracja on May 12, 2009 - 8:43 am

    The essence of eating is balance.
    There is not a single nutrient as fat or carbohydrates that makes you fat, but extremity.
    And it’s not weight that makes us feel bad (excluding anorexic person…), but proportions of fat to muscles in our body and general condition as well.
    So instead of denying yourself something valuable but “forbidden” try to eat everything in reasonable amount.
    It’s better for your health and mood, as “a dose of what you fancy does you good”.

  5. #5 by jay on May 12, 2009 - 10:28 am

    Where does that leave cholesterol concerns?
    My doctor indicated some years ago to cut down fat. (I’m on statins, active (though not an athlete) and not overweight.) Is there still considered to be a dietary fat/choleseterol link?

  6. #6 by Scott Simmons on May 12, 2009 - 11:17 am

    “When I was in college, fat was the enemy; there commenced a proliferation of products like Snackwells that were specifically created as fat-free goodies, and foods that had always been fat-free (e.g., pretzels), suddenly announced this on their packaging.”
    I still remember the first time I saw a bag of candy corn proudly labeled as “A Fat-Free Food!” Evidently their marketing targeted the intersection of the groups ‘low-fat dieters’ and ‘fucking morons’.
    “People don’t become fast by playing around with their diets, or more specifically, by placing severe restrictions on certain items (“foods” such as straight warm vodka excepted).”
    Well, there’s my problem right there! I haven’t been adequately chilling my vodka! (If this works, I am so writing a book. “Drink Your Way To The Boston Marathon”, I’ll call it.)

  7. #7 by Julie Stahlhut on May 12, 2009 - 12:24 pm

    Every time someone starts marketing the idea that we can lose weight by following a non-something diet, someone else makes even more money by devising and selling nutritionally worthless, unappetizing, non-something junk food that promotes overeating of some other source of empty calories. That’s how we got fat-free cookies that taste like sugared cardboard, low-carb desserts that taste like axle grease and saccharin, and a bunch of people spending lots and lots of money on horrible-tasting stuff that contains just enough real food to negate any calorie savings of the diet change.

  8. #8 by Julie Stahlhut on May 12, 2009 - 12:24 pm

    Every time someone starts marketing the idea that we can lose weight by following a non-something diet, someone else makes even more money by devising and selling nutritionally worthless, unappetizing, non-something junk food that promotes overeating of some other source of empty calories. That’s how we got fat-free cookies that taste like sugared cardboard, low-carb desserts that taste like axle grease and saccharin, and a bunch of people spending lots and lots of money on horrible-tasting stuff that contains just enough real food to negate any calorie savings of the diet change.

  9. #9 by Autumn on May 12, 2009 - 4:25 pm

    A particular fatty acid oxidation disorder has a very high prevalence in Alaska natives, enforcing the idea of selective pressures yielding genetic changes that adapt the population to its diet. Their diet was traditionally 85% fat and 15% protein, with little to no carbohydrate. This disorder allows the optimal usage of fat for fuel, as its oxidation is slowed in patients with this disorder so there is not as much wasted by clearance of ketone bodies in urine. The introduction of diet high in carbohydrate has led to an amazing prevalence of obesity and type 2 diabetes in this population, along with health problems related to this disorder, CPT-1 deficiency.
    One diet does not fit all, and never will. The populations of this world have each adapted separately to make their diet ideal for their body. Fad diets and foods cause more problems than they fix.
    On the subject of food company lobbying and advertising I could rant all day. Food companies can put (and in some cases leave off) anything they want on a label, as long as it includes the statement about lack of FDA evaluation. The only way to really know what you are eating is to read ingredients for everything and do your own research. I would encourage everyone to do this, if only for awhile, to bring up your awareness of the crap that’s in our food. It’s frightening.
    As far as cholesterol, typically any high fat food is also high in cholesterol. This especially applies to fatty meats. That is why a low fat diet is recommended for those with high cholesterol levels.
    I agree that balance and moderation are the key. Too much of any good thing is bad!
    An article that recently came out in the New York Times cited research that concluded that excess nutrition, ie: eating too much, was the reason for the obesity in America, more so than lack of exercise. Eat less of what you want, and everything will be okay. (This recommendation would have been put out a long time ago by nutritionists and government if it didn’t piss off the food companies so much. They want us to eat more so they make more money, and to hell with the consequences.)
    Here’s to a healthier America!

  10. #10 by L. Roy on May 13, 2009 - 9:05 pm

    “Any high fat food is also high in cholesterol.” Not true. Cholesterol is a product of an animal’s liver. High fat plant foods (i.e. avocados, tree nuts) do not contain any cholesterol.
    I’m coming to believe that so-called carb-craving is really fat-craving. Each cell membrane contains a lipid layer and we need a supply of healthy fats to maintain healthy cells.
    If we don’t we tend to eat and eat trying to get them.

  11. #11 by ray on May 18, 2009 - 4:24 pm

    1) fat calories as a percentage of total calories in the American diet have fallen over the preceding 20 years while overweight and obesity rates have increased drastically;
    I do not have the reference, but I clearly remember that the reason for the falling fat percrntage is that the absolute level of fat consumption stayed the same while carb consumption and total calories increased; the falling percentage of fat is a bit of a red herring.

  12. #12 by Neil B ♪ on May 25, 2009 - 8:31 am

    How about eating roughage-like stuff that takes up space and has little that can be absorbed to increase your weight? Popcorn, lettuce? There was a story awhile ago about some type of bean curd, something that has to be prepared at the right temperature, that can be a big part of diet and prevent weight gain. Sorry I can’t remember more.
    The basic change is more than what eaten, but growth of a culture of impulse. I think people were thinner in the 50s more from not “grazing” than from diet content per se, is that so?

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