Dietary Dogma: The latest dust-up over low-carb diets
Have you seen the headlines? Low-Carb Diet Reduces Heart Risk Factors! A new study (summarized here on Science Daily) finds that low-carb diets are more effective than low-fat diets in reducing the amount of inflammatory markers and saturated fats in the blood. That's right: even though a low-carb diet may contain more saturated fats, you may have more fat in your bloodstream if you follow a low-fat diet.
But hang on, where is that study that just crossed my desk a couple of weeks ago? Ah yes, here it is: Researchers at the University of Maryland found that people on the Atkins diet (50% fat) experienced increased cholesterol and inflammatory markers, compared with those on South Beach (30% fat) and Ornish (10% fat) diets.
(Incidentally, the first story got approximately ten times as much attention in the media and blogosphere than the second.)
But with conflicting scientific studies being released monthly, who are we to believe? How do we make good decisions about how to eat?
Part of the story is in the details. The first (pro-Atkins) study involved patients with metabolic syndrome (a pre-cursor to diabetes), in which metabolism is altered by insulin resistance. People with metabolic syndrome respond differently to carbohydrates, transforming them more readily into blood (and body) fat. These results are consistent with other studies (such as the one I blogged about here) finding that low-glycemic diets seem to be most helpful for people with diabetes and metabolic syndrome (but not as effective for others).
The second (anti-Atkins) study specifically looked at the weight maintenance phase. There are several studies showing that people on the Atkins diet experience improved cholesterol and triglycerides. But weight loss, by any means, is likely to improve cardiovascular markers such as blood fats and inflammation. The researchers designed this study to look at the effects of various diets when the (otherwise healthy) subjects maintained their weights. And, indeed, it appeared that the high-fat diet had several undesirable effects, consistent with previous studies such as this one.
So, where does all this leave you? Livin' la vida low-carb or doing the low-fat lambada? As noted in yesterday's post on salt, you can probably find some research study to support whatever position you want to take. Here's my two cents' worth:
1. Do what works. The pros and cons of various diet styles notwithstanding, the most important thing is to maintain a healthy weight. If a low-carb diet is the only way for you to do it, then the possible risks are probably justified.
2. Consider your health history. If you are diabetic or have metabolic syndrome and have weight to lose, a lower-carb diet may be a better choice. If you are otherwise healthy and are simply trying to maintain a healthy weight, a moderate-fat, controlled-calorie diet may be the best choice.
3. Monitor your risk factors. Regardless of which dietary dogma you ascribe to, have your cholesterol, triglycerides, and inflammation markers (CRP) tested on an annual or bi-annual basis.
4. Don't over-simplify. I think an underlying truth in all of this conflicting research is that looking at diets only in terms of macronutrients (fats, proteins, or carbohydrates) is overly simplistic. All fats are not the same: Trans fats are highly inflammatory and atherogenic while monounsaturated fats are the opposite. Similarly, a diet rich in low-glycemic carbs like vegetables and legumes is not going to have the same negative effects as a diet high in high-glycemic carbs like rice cakes and white bread. Even proteins are not all equivalent: chicken liver, for example, is quite inflammatory (because of its high arachidonic acid content) while tuna is anti-inflammatory.
One of the reasons I use Nutrition Data for my own research and diet planning is that it offers so much more detail about what you are eating. In addition to showing you macronutrient ratios, you also see the inflammation factor, the estimated glycemic load, and many other tools that can help you find a balanced, healthy, and effective diet strategy.
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Posted by: Cliff | Dec 7, 2007 5:28:48 PM
Monica,
Have you read "The 80/10/10 Diet" by Douglas Graham? I recommend it.
Posted by: Kathleen | Dec 17, 2007 9:41:06 AM
Monica,
I can't find the amount of gluten per food item. I recommend ND include this info. It would help those of us with gluten issues. ND would then be my complete food research site.
Posted by: mike pastore | Dec 18, 2007 5:36:34 PM
Why isn't the amount of potassium listed in the ND breakdown of foods? A Harvard medical study says we need 4.7 grams/daily. That's 4700 mg. Unless you eat avocados and dried apricots each day, it's pretty hard to to reach 4.7 grams. For instance an over-the-counter potassium supplement is only 88 mg (limited by the government).
Posted by: Monica Reinagel | Dec 19, 2007 8:22:38 AM
Mike,
the potassium content (when known) is listed in Nutrition Data's analysis. You can also use the Nutrient Search tool to find foods high in potassium. I'd be curious to see the study you're referencing. Do you have a link?
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Asking
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Posted by: Little Miss Diets | May 13, 2008 3:34:20 PM
This highlights a really important issue with diets as conflicting studies do very little in helping those who actually want to lose weight. Who do we trust and who do we believe?
Posted by: jackieg | Sep 18, 2008 2:49:16 PM
I’m wondering what other people think. I’ve been doing some research on healthy eating and low carb diets in particular and came up with this one site called OpposingViews.com where there are debates by experts on various subjects. There is one debate called: “Are Low Carb Diets Healthy?”.
I like the idea that these people are experts in their fields, but this one guy says something that gives me pause. He says something to the effect that eating whole plant foods is associated with having good health but diets high in animal protein and fats are not. He also says that in a global sense, a sustained low carbohydrate diet which comes mainly from animal foods creates significant challenges for the planet and also other health issues for people such as antibiotic resistance.”
What do you think he means when he says that a diet which comes primarily from animal proteins is bad for the planet? That’s the first time I ever heard that. If you have time, take a look and let me know what you think by posting your comment. Thanks! http://www.opposingviews.com/questions/are-low-carb-diets-healthy
Posted by: Betsy | Oct 31, 2008 1:44:33 PM
jackieg
I think the environmental effects he is referring to are related to 1) antibiotic use in food animals (which does contribute to the development of antibiotic resistant bacteria) and 2) the "carbon footprint" of food production (meaning it takes lots more energy to raise a pound of beef than it does to raise a caloric equivalent of corn, etc.) I'm sure you could find more information on the web.
Posted by: Adrienne Larocque | Feb 15, 2009 6:43:49 AM
JackieG: the comment about diets high in animal protein and fat means that you could eat the corn directly, or you can feed it to a cow and then eat the cow. The problem is that only about 10% of energy is passed on from one trophic (feeding) level to another, so it takes 10x as much corn to feed a cow to feed you than it would to feed you directly.
Having said that, I'd like to point out that agriculture (particularly in the form of growing grains) is the worst thing that happened to the planet because it allowed humans to get out of equilibrium with our environment. If we had to fish and hunt and gather nuts to eat, there wouldn't be nearly so many of us!
Finally, I've learned through personal experience and health challenges that my body requires animal fat and protein to be healthy, but it does not require carbs. Because I am insulin resistant, as is anyone who is overweight, I simply cannot eat carbohydrates and maintain my health. So I choose to eat meat, and do what I can for the planet in other ways.
Check out these links to find out more:
http://proteins-carb-fats.suite101.com/article.cfm/what_not_to_eat
http://diet-trends.suite101.com/article.cfm/are_lowcarb_diets_safe
http://weight-loss-motivators.suite101.com/article.cfm/the_right_way_to_lose_weight
http://weight-loss-methods.suite101.com/article.cfm/how_to_start_losing_weight
Posted by: Sal | May 22, 2009 3:32:45 AM
LOL Monica, I love this article. It is amazing how all these studies contradict each other! Have you seen this report about a study that compared different diets and found that they are all equally effective? You are just so right. Find out what works for you personally and stick to it!
http://optimalbodyweight.com/blog/choosing-a-diet/just-when-you-think-you-know-how-to-lose-weight
