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February 26, 2009

Weight-loss study re-confirms laws of thermodynamics

A new study shows that cutting calories, any kind of calories, leads to weight-loss:

That is the finding of the largest-ever controlled study of weight-loss methods published on Wednesday in The New England Journal of Medicine. More than 800 overweight adults in Boston and Baton Rouge, La., were assigned to one of four diets that reduced calories through different combinations of fat, carbohydrates and protein. Each plan cut about 750 calories from a participant’s normal diet, but no one ate fewer than 1,200 calories a day.

While the diets were not named, the eating plans were all loosely based on the principles of popular diets like Atkins, which emphasizes low carbohydrates; Dean Ornish, which is low-fat; or the Mediterranean diet, with less animal protein. All participants also received group or individual counseling. [NYT]


On average, all the groups lost (13 lbs) and subsequently regained (4 lbs) the same amount of weight.

The researchers also found a great deal of variability in between individual dieters assigned to the same programs. Next on their research agenda: Trying to understand why some people lost a lot more weight than others on the same diet.

Defenders of fad diets will seize on these individual differences as evidence that diets have to be tailored to individual "metabolic" differences. Cue the woo.

It's possible that diet itself wasn't responsible for the different amounts of weight loss. Maybe the subjects who lost the most weight were just the most conscientious dieters (or "cheaters" who ate less than the researchers told them) or the people with the fastest metabolisms. It's also possible that individual food preferences influenced compliance.

We won't know without further research.

[HT: Jezebel.]

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Comments

Love the headline.

Many adults would like to lose more than 9 pounds.

A study in which people on a variety of diets only kept off an average of 9 pounds after 2 years isn't good news for them.

The thing that always got me about the Atkins Diet was that it never proclaimed that you didn't have to cut calories, merely that, if you ate in a hunger-driven manner, and kept your carbs in a controlled range, you would lose weight.

The logic seemed to be, keep your carb intake controlled, and your hunger would be controlled, you wouldn't eat as much, voila, you'd lose weight.

It always made a huge amount of sense to me. I'm sure there are other diets that work similarly, too, and that's what I think people should consider.

You need to get all your nutrients; you can't walk around hungry more than once in a while; you have to be able to figure out what you can or can't eat easily; and you have to be able to be happy with what you can eat.

Apparently this study shows that all that doesn't matter - what matters is reducing calories.

Their example of a so-called 'high fat' diet (40% of calories from fat) is not really high fat at all. One clue to this can be found by looking at their meal plans (here, if you're curious). The 'high fat' diet includes food items like
- skim milk
- low fat cream cheese
- vegetables and pasta cooked without any added milk or fat
- lean roast beef

... and so on. It would be trivial to bump up the percentage beyond 40% by using whole milk, vegetables sauteed in butter, mashed potatoes made with cream, etc. (of course, quantities would have to be reduced if you still wanted to be consuming only 1400 Kcal).
So while their results are interesting, they haven't studied a high fat diet at all. A real example of a high fat diet would have 60-80% of calories from fat (see here if you think this is implausible for some reason).

Large controlled studies of truly high fat diets over long periods of time hasn't been done. But there's a reason: Most institutional review boards wouldn't consider it ethical to recommend such a regimen to human subjects.

Apparently this study shows that all that doesn't matter

As evidence against the claims made for various radical diets, it actually falls flat. Mainly because the carb/protein/fat ratios they studied were all fairly tame. Most proponents of things like the Atkins diet focus on reducing carbohydrates to a very low level with a view towards triggering a specific change in metabolism (entering ketosis), and the carbohydrate levels in these diets aren't low enough to evaluate that. The most moderate of the low-carb diets (the Zone diet) suggests 30% carbs (lowest in the study was 35%), while Atkins would go down as low as 20% or even less. And that doesn't even get into diets whose theoretical basis has little do do with the carb/fat/protein balance, and more to do with some other aspect of the food.

There have been studies of Atkins, and I consider that high-fat.

I'm a vegan and I'm not suggesting anyone eat the following, but it seems high-fat:

=====================
Atkins - Bacon-Cheddar Cheese Soup

BACON-CHEDDAR CHEESE SOUP
Servings: 4
Prep time: 0:05:00
Bake/Cook time: 0:15:00
Calories: 567
Fat: 44 grams
Protein: 29 grams
Carbohydrates: 9 grams
Fiber: 1 grams
Net Carbs: 7 grams
4 strips bacon
1 small onion, chopped
1/2 teaspoon dry mustard
1/4 teaspoon freshly ground pepper
1 can (14 1/2 ounces) reduced-sodium chicken broth
4 teaspoons ThickenThin Not/Starch Thickener
2 cups half-and-half
12 ounces shredded cheddar cheese
1/2 teaspoon paprika (optional)
1. In a large saucepan over medium heat, cook bacon 6
minutes, until crisp. Remove and drain on paper towels.
Crumble bacon.
2. Add onion to bacon fat in saucepan; cook 3 minutes,
until onion just begins to brown.
3. Add mustard, pepper and broth. Bring to a boil. Reduce
heat to low. Whisk in thickener. Add half-and-half,
cheese and paprika; stir until cheese is melted. Ladle
soup into four heated soup bowls. Garnish with
crumbled bacon.
Sharp cheddar combined with the bite of dry mustard and the
smoky taste of bacon makes a quick, tasty and filling soup.
Atkins - Bacon-Cheddar Cheese Soup
==========================

Atkins is high fat. Has to be, or it would harm you. If you restrict yourself to (say) 200 calories' worth of carbs per day, while still taking in 2000 calories overall (in keeping with the notion that you don't need to restrict overall caloric intake), that's 90% of your calories from fat or protein. Even an even split (45/45) of the remaining calories between fat and protein would put quite a load on your kidneys, and you don't really have any use for that much protein. 60% fat and 30% protein would make more sense. And going really high on the protein would lead to rabbit starvation.

The physics of weight loss deserve more study. Reducing gravity would have a huge impact of course. Quantum weight loss offers a dizzying number of possibilities, I think, but I don't understand quantum physics.

Large controlled studies of truly high fat diets over long periods of time hasn't been done. But there's a reason: Most institutional review boards wouldn't consider it ethical to recommend such a regimen to human subjects.

You could make an even broader statement and say that large controlled studies of very unusual diets haven't been done; and not even so much for reasons of ethics as because getting thousands of people to eat some particular diet, for years at a time, is simply very hard. Or expensive, if you try to compensate them for the trouble. The ethics could probably be addressed by promising ongoing evaluation and a willingness to abort the study if the negative effects looked too bad (which after all is standard if you're testing drugs).
in any case, the limited studies that have been done suggest that the ethical problems aren't as grave as you suggest.


THIS IS ALL NONSENSE

I don't buy any of it. There is a secret conspiracy between the clothing industry and the weight loss industry to get us to buy there stuff when we don't really need it. I've seen this first hand. At different times in my life I have seen my entire wardrobe shrink little by little, all at exactly the same time, in exactly the same proportions. What are the chances of that happening?

Result, I have to buy a lot of new, expensive clothing and waste time, money, and effort on diets. After a while (Yes, you guessed it), all of my clothes start shrinking again. Sometimes the shrinkage is almost imperceptible. In the end, it's inexorable and I am left with nothing to wear, and believing I have to spend again on clothes and diets.

Now I'm on to them. If history is any judge, by next year the shrinking will commence, again. They have it down to a science. Next time I'm going to expose them, those conspiratorial bastards. I'm going to get even, too. From now on, when I buy clothes, I'm going to garage sales and consignment shops and get someone else's clothing that has already been shrunk. And I won't spend anymore money on those stupid diets. That'l fuggin learn 'em.

I'm not surprised that it was hard to tell the difference between different fad diets. However, it doesn't suggest this:

Defenders of fad diets will seize on these individual differences as evidence that diets have to be tailored to individual "metabolic" differences. Cue the woo.

You can't use the study to dismiss this claim. What you can say is that we still know so little about it that we couldn't reasonably tailor a diet to an individual and predict its chances of success.

The chances of any weight loss lasting more than five years is extremely low for most people. Keep the eye on the prize.

Mandos, I made the same point in the post--it is possible that some diets work differently for different people, maybe even because of individual differences in metabolism --but most of what fad diet defenders claim to know already is woo, at best untested and at worst complete pseudoscience. I'm talking about stuff like "Eat Right for Your Type."

Bart, if you're studying people who already eat a certain way, that's not controlled research. It's research, but you're not randomly assigning people. Maybe the people who choose to eat a very unusual diet are different in important respects from the rest of us.

LHW writes: "You need to get all your nutrients; you can't walk around hungry more than once in a while; you have to be able to figure out what you can or can't eat easily; and you have to be able to be happy with what you can eat."

I think walking around hungry more than once in a while is the key to losing weight and keeping it off. Hunger ranges from the ability to just eat one more spoonful of ice cream all the way to horrible cramping and lightheadedness. Your body will let you know if you have less fat than you used to have by making you hungry; at least that is the gist of what I got out of Science a few years ago. If you used to weigh 200 lbs and now you only weigh 185, you will feel hungry. Not real hungry, but you will feel hungry. The key is to regard a certain feeling of hunger as normal and desirable. I think our relatively sedentary, brain-work-oriented lifestyles makes this hunger distracting and sometimes even unbearable; I notice it much less when I am doing physical work or recreation.

I have been on many diets; some fad and some just cutting back on how much I ate. They all work as long as you stay with them. Therein lies the problem. At some point you reach your goal weight and then start to regain. Unless you make a total life time commitment regaining the weight is inevitable no matter what diet you are on. How many of us really will change the way we are for the rest of our lives?
Richard Complainary, Publisher
http://www.complainary.com/

Yes, that's exactly the problem. Over the kind of time-scales that dieting needs to have a long-term effect, "willpower" just becomes another biological attribute like height and metabolic rate. We don't exist in isolation as beings powered by our Triumphant Will.

The weight loss that is most likely to be maintained is that lost by exercise, it seems.

"Weight-loss science" is an oxymoron.

I have been on a lot of different diets. I am losing weight on the Atkins program now. It is incredibly slow but I find that I never feel deprived, never feel the lightheaded hunger. I never crave sweets anymore. Sweets have always been my downfall. Thus, I believe that it is always about eating less than before, but you will only stick with something that you enjoy. Soon will be switching to Sugar busters because I think the low carb thing has been good for me. I think the study is a good start. If I were obese, I would be discouraged by this study - which absolutely states they did not study the Sugar Busters or Atkins approaches. It was a different diet so the original post has it wrong.

I think walking around hungry more than once in a while is the key to losing weight and keeping it off. Hunger ranges from the ability to just eat one more spoonful of ice cream all the way to horrible cramping and lightheadedness.

I've never seen anyone define hunger as "the ability to just eat one more spoonful of ice cream". It strikes me as a very foolish definition, since a person can be stuffed to the point of mild nausea, but still able to eat one more spoonful of ice cream.

Hunger's a pretty ambiguous concept.

For some purposes, hunger just means a disposition to eat. If you ate a lot before you felt satisfied, you were very hungry. On this view, you could say you were still hungry until the last bite--you only stopped eating when you stopped being hungry. So, someone who's one bite away from being satisfied is still a little hungry.

Alternatively, you can define hunger as a feeling, or as a category of feelings. If you're experiencing hunger pangs and lightheadedness and intense preoccupation with food, you're hungry. Or, maybe you're not feeling like that, but you see a slice of pizza and you're hit with an intense craving, whether you're away of the physical sympatoms that your body needs food or not.

Sometimes dispositions and feelings go together, but sometimes they don't. When you ask someone whether they felt hungry while they were dieting or trying to maintain their new weight, you should clarify what they're talking about. It's one thing to say that you have to endure hours of hunger pangs and headaches every day. It's quite another to say that you have to resist your pizza cravings three times out of five. Most people couldn't stand the former over the long term, because it actually involves feeling at least mildly sick for a good part of every day. A lot of people could probably deal with rationing their pizza intake for the rest of their lives if they didn't have that gnawing sick feeling of hunger.

I'm a physicist. Thanks for posting this, Lindsay.

Eat food. Not too much. Mostly plants.

Michael Pollan got it right in seven words. "In Defense of Food" is a good read. Pollan also points out that there is ample evidence for diets that work (hint - look outside the US). Then there's Marion Nestle:

Eat less. Move more. Eat mostly fruits and vegetables.

Also correct in only nine words. So much bloviation about diet, when it boils down to energy balance and willpower. The French and their puericulture are much smarter about food and diet. Our animal relatives are also much smarter than we are about eating. It turns out the physics diet is correct. You can't violate the 1st law of Thermodynamics. Food calories are a form of energy.

Pollan's stuff is complete woo as well. In order to drive his points, he ignores or misrepresents nutritional science, using scare words like "nutritionism," and idealizes some holistic notion of a national cuisine.

Nutrinionism is a concept defined by Gyorgy Scrinis in peer-reviewed articles like this.

Pollan gives many references in his book to scientific research articles. His writing is based on real-world evidence. Have you read the book, Mr. Levy?

Hunger's a pretty ambiguous concept.

For some purposes, hunger just means a disposition to eat. If you ate a lot before you felt satisfied, you were very hungry. On this view, you could say you were still hungry until the last bite--you only stopped eating when you stopped being hungry. So, someone who's one bite away from being satisfied is still a little hungry.

I'll give you that... it is ambiguous. I know that if I'm bored out of my skull, and in dire need of stimulation of some kind of another, I can get "hungry", even though it's not really food that I want. (I mean, heck, I've gotten "horny" in that state, when my normal (whatever *that* means) libido should have been well fed.)

But there needs to be a word to say "you have a hard-to-ignore sense that your body wants to be fed". And that's what one's nutrient intake should address. If you want to eat a certain way, and obtain a stable weight, you can't be constantly recognizing that you want more food because of whatever-physical-drive it is that makes us "hungry" in the physical sense.

The analogy I heard went something like "you can, for a short time, use less oxygen by breathing more shallowly, or by holding your breath, but over the long term, you'll only be comfortable if you're breathing normally."

That's how I think eating should be, over the long term... like breathing normally.

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