Thursday, August 5, 2010

Low-Carb versus Low-Fat


Ladies and gentlemen of the low-carb community: We have a hat-trick.

1. On March 7, 2007, the Journal of the American Medical Association (JAMA) published an article showing that, at 12 months, women assigned to the Atkins (low-carbohydrate) diet lost more weight and experienced more favorable metabolic effects than did women assigned to follow the LEARN, Ornish or Zone diets.

2. On July 17, 2008, the New England Journal of Medicine published an article describing a two-year study of men and women in Israel. The study showed that, compared with the low-fat diet, the low-carbohyrate diet produced greater weight loss and had more favorable effects on lipids. The authors concluded that low-carbohydrate diets may be an effective alternative to low-fat diets.

3. And finally on August 3, 2010, the Annals of Internal Medicine published an article describing a two-year low-carb vs. low-fat study of men and women in the United States. The authors concluded that, "Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment. A low-carbohydrate diet is associated with favorable changes in cardiovascular disease risk factors at 2 years."

Three refereed articles in three well-respected journals. Although the second study had some funding from the Dr. Robert C. and Veronica Atkins Research Foundation and might be faulted for that reason, the first and third were supported by the National Institutes of Health (NIH). All three studies showed that a low-carbohydrate is effective for weight loss. All three showed that metabolic effects, including an increase in HDL cholesterol, improved with the low-carbohydrate diet. And while the first study lasted a year, the last two studies covered a two-year span, demonstrating that the benefits of a low-carb lifestyle are not limited to a few weeks or months.

Currently the third article is only available for free in abstract form. However, Jimmy Moore purchased the article and did an excellent summary which can be found here. I purchased the article, too, and found that most of my observations agreed with Jimmy's, so I'll refer you over there if you would like a thorough discussion of what the article showed. [Great news! Thanks to LynMarie Daye in the Comments, we now have a link to a free PDF of the entire article: Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet.]

I'll just emphasize a few points.

First of all, the people in the third study lost an average of 11 kilograms at six months, while the average six-month loss for low-carbers in the first two studies was about 6 kilograms. That's probably because the average BMI in the third study was about 36, vs. about 31 in the other two studies. As a general rule, the more a person weighs, the easier it is to lose a given amount of weight.

Second, in the Annals of Internal Medicine study, the low-carb dieters lost (and regained) almost exactly the same amounts of weight as did the low-fat dieters. This may be because both groups received regular instructional sessions lasting from 75 to 90 minuntes throughout the two years of the study. Or it may be because the low-carb group was treated differently from the low-fat group. The low-carb group began the study at 20 grams of carbs per day, but at three months they were raised 5 grams of carbs per week until they reached a level of carbs at which they could maintain their weight. The low-fat group began the study eating 1200 to 1800 calories per day with less than 30% of their calories from fat, but they were never transitioned to a maintenance level of calories per day. In contrast with the low-carb group, at the end of the study the prescribed regimen for the low-fat group had not changed. It is hard to know how much additional weight the low-carb participants would have lost if they had been allowed to transition to their Critical Carbohydrate Level for Losing (i.e. the number of carbs that would allow them to continue losing 1-2 pounds per week) rather than being moved directly to a maintenance program.

Third, the weight loss in the low-carb group was not a loss of water weight. Both groups experienced similar reductions in lean mass (about 5%) and in fat mass (11% to 20%).

Fourth, in all three studies, the LDL cholesterol increased for the low-carb groups at three to six months, but was at or below baseline by the end of the study. Why this happens is not clear, but it seems to be a common finding when people begin a low-carb diet. Unfortunately none of the three studies measured LDL particle size, an important factor because small, dense LDL particles are more atherogenic than large, fluffy LDL particles. And people with higher HDL, as was seen in the low-carb group, tend to have the large, fluffy form of LDL cholesterol.

Fifth, an interesting aspect of the Annals of Internal Medicine study was the fact that it addressed the issue of dieting and bone loss. Both the low-carb and low-fat groups lost 1.5% or less of their bone mineral density during the course of the study. A small loss is unsurprising because the bones of both groups had less weight to carry as the study went on. However, there was no between-group difference in loss of bone mineral density in either the hip or the lumbar spine. There are blogs all over the internet suggesting that the relatively high protein intake of a low-carb diet causes calcium to be leached from bones and results in osteoporosis. The theoretical basis of this idea is shaky at best, and in a practical sense the Annals of Internal Medicine study indicates that this type of fear mongering is unfounded.

To sum it up, low-carbers now have solid scientific evidence that low-carb works for weight loss and that it improves metabolic health markers as well. If your doctor objects to your practice of the low-carb lifestyle, you might want to print out these three articles, read them, and take them along to your next office visit. For those who are skeptical about the benefits of low-carb, the positive scientific evidence is only getting stronger.

18 comments:

onecoolbean said...

My wife and I both did a 6 week VLC diet (using HCG, though that might be controversial?) and lost around 25 and 17 lbs respectively. We finished this about 12 weeks ago and have stayed within 2 lbs of our ending weight. We are continuing with a low carb diet (definitely no wheat and only occasional experiments with quinoa and wild rice and legumes). (Incidentally, my triglycerides went from 177 to 36.) We seem to be unable to add carbs without almost immediate weight gain. Here are a few questions:

1) Though I know this gain may be due to water, how can we know when our bodies can resist the reflex to turn the carbs directly into tri-glycerides and store them?

2) My blood sugar levels rose significantly. 2 years ago (along with 177 triglycerides) my blood sugar level was about 80. Now it measured at 185. Any comments? Is it possible I am eating too much protein?

3) Could you give any comments on re-introducing carbs. Of course I don't mean returning to a high carb diet, but I want to assume 80-100 grams/carbs ought to be possible for most people. Reflecting on your last post about hunger between meals, indeed how do we re-establish a healthy metabolic response? I have generally hardened myself to never have sugar or white carbs again, but surely (except in the case of allergies) complex carbs in moderate quantities (<100g) ought to be possible. We keep reminding ourselves it took 40 years to sicken our metabolic processes: will the passing of time "re-set" our system?

Thanks.

Stargazey said...

Hi, onecoolbean, and thanks for your questions.

First of all, always remember that I am not a physician. I am not qualified to give medical advice, so what I'm going to say is more in the realm of thoughts and ideas. So here are some thoughts and ideas.

An important consideration is that you don't give your age or your wife's age. One of the things I've learned is that carb metabolism seems to deteriorate as we get older. An eating plan that worked when we were in our 20's and 30's is not as successful once we start to approach age 50.

No matter what your age, your weight gain from eating carbs may be caused by the fact that carbs can be stored as glycogen and glycogen is stored along with water. By weighing every day and thinking about how many carbs you ate the day before, you can generally get a feel for whether or not your increased weight is water weight. Water weight will tend to fluctuate around a particular point, but when the set point starts rising, then you know that you’re gaining fat.

If you are older, you will find that you probably can’t eat 80-100 grams of carb per day and get away with it. The number will be more like 30 per day, though the exact amount will be unique to each individual. And for any age, complex carbs are the same as simple carbs. The digestive system is engineered to convert complex carbs to simple ones very efficiently, and both complex and simple carbs cause a release of insulin. The only difference is that the complex carbs take a little while longer to do it. All types of grains, both whole grains and refined ones, are essentially a slowly-released form of sugar. You may find that you need to avoid grains as much as possible and that you have to get your carbs from low-carb vegetables and fruits.

Specifically, when reintroducing carbs, I would recommend the one-food-at-a time approach. Use a notebook and make observations. Does the new food cause cravings? Does it produce symptoms of inflammation in your stomach or joints? If you don’t observe any negative side effects for about three days, then you can probably move on and try introducing another food that contains carbs. Everybody’s “allowable” carbs are a bit different, so your list will be unique.

As far as your blood sugar on low-carb, 185 is definitely high, even if you are near 50 and are eating too much protein. You should probably talk to your doctor and see what he or she recommends. This may be a signal that you are developing type 2 diabetes, a disease that needs to be taken very seriously.

If your metabolism is damaged, it probably can’t be repaired. The good news is that for many people the high blood sugars, high triglycerides and other metabolic problems can be managed, depending on what you eat and how you exercise. That helps avoid ongoing damage, and it may allow you to drop some medications, but your body won’t return to the state it was in your 20’s.

I think this answers most of your questions, though not exactly in the order you asked them. Once, again, remember that I have a Ph.D., not an M.D., so please take these as thoughts, not as clinical advice. Best wishes on your low-carb journey.

onecoolbean said...

Thanks for the comments. I'm not expecting medical advice, just trying to understand how things work.

First I am suspecting the glucose level is a mistake or I am misreading the results. I am in the UK and they may be using a different test. I will sort this out as the clinic considers this "normal".

BTW, I am 42.

Could you clarify why the slower metabolism of complex carbs wouldn't result in lower triglycerides and thus less weight gain? I thought that the slower metabolism of complex carbs means that there is less likelihood of an excess in blood sugar since the cells can utilize more of the carbs right away. Whereas with simple carbs, the body simply doesn't need the large surge in blood sugar and so converts the much larger excess to triglycerides in the liver for storage.

Also, when we use the term metabolism, do we mean how fast our body "uses" its available energy (whether from stores or from a recent meal)? What term is used to refer to the process of feeding cells by the release of energy stored in fat cells?

DogwoodTree05 said...

off-topic question: How important is vitamin C? I ask because as far as I know, it is found only in produce, not in animal foods. I don't like fruit much. I do like some veggies high in C like broccoli, red peppers, brussel sprouts, and parsley, but I eat only seasonal produce grown locally, so my daily vitamin C intake varies. I do take a 500-mg Ester C that is labeled "made in USA." How do groups that eat mostly animal foods get enough vitamin C? Sorry to post off-topic, but you don't have a Q&A forum, and given the small number of commenters, you probably don't need one.

LynMarie Daye said...

Thanks for sharing your thoughts on this recent study!

I have a rather odd question though. You stated that you and Jimmy Moore had to purchase the full text, yet it seems to be available for free here: Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet

This link may also work: Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet. Click on "Original Version (PDF)"

Is this a valid version of the study? And if it is, are you going to demand a refund? Just kidding! :)

onecoolbean said...

A few of my thoughts on vitamin C:

Taubes in _Good Calories Bad Calories_ suggests that the body can make vitamin C on its own, as demonstrated by the Intuits (p. 322f), but that excessive carbohydrates interfere with vitamin C absorption. I assume he is suggesting that low carb dieters will not need as much vitamin C and that their bodies can probably produce their own.

Personally, I still take 1000 mg a day (even before the low carb diet) and don't plan to stop.

On another note, some have suggested (I will leave off names) that vitamin C in its ascorbate form is most readily available to the body. There are only a few sources for this: you can google it if interested.

Finally, one strategy might be to drink warm lemon/lime juice in the mornings before anything else. Apparently this helps with body pH as well as with liver function, and you get the bonus of a boost of vitamin C.

DogwoodTree05 said...

Thanks, onecoolbean. Given the high longevity of some northern latitude ethnic groups, I suspected that large amounts of vitamin C daily are not required for good health. I squeeze a little lemon into the 4+ cups of green tea I drink daily. Why does the lemon juice have to be warm? Doesn't heating destroy C?

Stargazey said...

Hey, you guys are having a great discussion! I'm distracted with some real-world responsibilities right now, so I can't chime in.

Except to say to LynMarie Daye that those links are indeed the article in question. When I get time, I'll put the one for the PDF into the blog text so others can get access to it without forking over $15.00 for the privilege. :-)

LynMarie Daye said...

@DogwoodTree05

I think this article will answer your question about animal foods and vitamin C:

The Inuit Paradox

@Stargazey

You got off pretty easy with the $15. A lot of journals charge $40! ;-)

Stargazey said...

Thanks to everybody for their comments on Vitamin C. I think my position aligns most closely with the link that LynMarie gave on the Inuit Paradox.

Specifically, if you're eating raw meat (especially raw organ meat) and if you aren't eating very many carbs, the rules for a recommended daily allowance of 60 mg (or whatever is the current number) no longer apply. You can get what you need from your food. Personally, I don't eat many carbs and I do eat raw-ish beef, but I don't eat organ meat, so I take supplemental Vitamin C daily just to be safe. There is some literature that taking too much C will produce an oxidant rather than an antioxidant effect, so I would recommend staying away from large doses of C.

Stargazey said...

Onecoolbean's questions are a bit harder. :-)

As far as metabolism, what I was talking about in my comment was the processes involved in breaking down food to yield energy and to synthesize substances needed for the maintenance of life.

You asked, "Could you clarify why the slower metabolism of complex carbs wouldn't result in lower triglycerides and thus less weight gain?"

I think you may have a misunderstanding of what happens to carbs when they are digested into monosaccharides in the gut and then absorbed into the blood. A normal blood glucose is about 85 milligrams per deciliter. That's the equivalent of one teaspoon of sugar in your entire blood volume.

A blood glucose higher than about 85-100 mg/dl is POISON to your body. It glycosylates proteins and creates all sorts of havoc. That's why your body releases insulin in response to ingested carbohydrate--the idea being to get the excess glucose out of the blood and taken up by the body's cells as soon as possible.

You seem to be talking about ensuring a steady stream of carbs being digested, moving into the blood, being taken up by cells and then being used for energy. I suppose that's theoretically possible, but it would result in chronically elevated insulin and eventually in insulin resistance.

On a practical level, because we cannot eat constantly (especially when we are sleeping) we have to store some of our food as fat and then access it later. That's no problem in a person who does not have insulin resistance. But once insulin resistance develops, if we are eating complex carbs and are keeping our insulin levels relatively high, it becomes harder and harder to access the stored fat. That's why a low-carb diet is such a good thing. It does an end run around all that whole carb/glycosylation/insulin/insulin resistance positive feedback loop and lets you fuel your body with fatty acids and ketones.

Also, the body should not be converting any excess carbs into triglycerides in the liver for storage. That's called fatty liver and is fine for foie gras, but not for people. Are you possibly talking about converting excess carbs into triglycerides in adipose cells?

You also asked, "What term is used to refer to the process of feeding cells by the release of energy stored in fat cells?" I think you're referring to oxidative phosphorylation, but I may be misunderstanding your question.

In fact, chances are good that I'm misunderstanding your other questions, too. If that's the case, try asking them again and I'll try answering them again. Thanks for your patience!

LeonRover said...

Hello OneCoolBean.

I have been following a pretty low carb diet for some 3 years now. That is, except when I've been on skiing trips and eat just what is there, tho' taking less carb food, when alternatives are available.

Before I went on keto my BGs were good, tho' not excellent. I've a meter for some time and would do an "at home" OGTT occasionally. They were always in order. However my fasting BG could be 95 or over tho' not always. I forced my GP to get my HbA1C and when it came back at 5.4%, I did not worry too much. When I first went keto I was quite rigourous and used ketone strips to check ketosis and regularly took my morning BG. Perhaps on average it went down. Then I just stopped testing.

On coming back from skiing this year, I could see I'd had a bit of fat loss in places, tho' not evident on scales. I concluded I had refilled part of my glycogen stores, including its added H2O.

I decide to start upping items like beans and some potato, to an acceptable level, as I just like the TASTE so damn much. Before starting I did some tests. My fasting BGs were in high 80's - good. Next I did an OGTT with 70 gm of dextrose as the dose. I was shocked to find that I had readings up 195 and it took 4 hours to get down to 130, hmmmmm.

Various bits of research reminded me that it's recommended to eat about 250 gm of carbs per day for at least 3 days, to upregulate the BG insulin response rate; it took 5 days for me eating about 150/day! My OGTT was fine. At that point, I was happy enough, and decided not to bother with HbA1C, to confirm I did not have an impaired glucose tolerance.

I'm recounting this to say that if my FASTING BG were up in the 180's, I would check it out with my GP and perhaps a diabetes registrar. I have 2nd hand experience of this, as my step-son was diagnosed with Type 1 fifteen years ago. It is one of the reasons I have a meter. In his case we had to worry about hypos!

However, I note, it takes the body up to 6 weeks to upregulate to ketone fuel, and it also takes some time to re-regulate back to CHO fuel, and some blood tests may be out of kilter.

Hope this (anecdotal?) narrative helps.

PS During this experimentation I swiftly put on 5 lbs and 1 waist inch, so I'm back on a meat and a little fruit eating plan.

LeonRover said...
This comment has been removed by the author.
onecoolbean said...

Thanks Everyone,
I finally got my BG results sorted and mine is 86. I made a mistake the first time around, so now problem there.

We are about to travel and will soon have no choice but to consume many more carbs (rice, flour, potatoes) than is good for the progress we have made so far. In preparation we are trying to increase our carb intake and find out especially how we respond to those three. So far so good--rice seems OK if we eat a normal serving (which of course is less than one normally thinks of). The country we are going to eats a lot of white flour, noodle like dishes, often with no way of just eating less of the starchy stuff.

Besides trying to make sure our bodies have gotten through the process that LeonRover described, I am thinking to take supplements like cinnamon and chromium to help with blood sugar while I am there. I think i can also manage to stick with a protein shake for breakfast.

Our trip lasts three weeks. Any other advise out there?

PS. I do have some follow-up questions on Stargazey's comments, but have not had time to digest all that was said.

Stargazey said...

Have a great time on your trip, onecoolbean! Most European countries offer excellent low-carb friendly foods, but perhaps you're going to a place that's more third world.

You may find it helpful to bring along small bags of nuts, protein bars and beef jerky. Depending on your destination, it may also be possible to buy cheese and summer sausage (or something like it) at a convenience store. That way you can eat the low-carb portions of the meals you're served and if you're still hungry later, you can have a snack from your low-carb stash. Eggs are good for breakfast.

By the way, the challenge at work has turned into a major meltdown. (We own our own business and it's a constant source of excitement.) Once things settle down, I'll get back to posting, but right now I have to cover two fulltime jobs, so comments are the most I can manage. Sorry about that. :-)

Goomama said...

I am curious about your comment that initially LDL levels go up after starting a low-carb diet:

"Fourth, in all three studies, the LDL cholesterol increased for the low-carb groups at three to six months, but was at or below baseline by the end of the study. Why this happens is not clear, but it seems to be a common finding when people begin a low-carb diet."

Do you know anything else about this? Have you seen documentation of that phenomenon elsewhere?

Stargazey said...

Goomama--no I haven't.

Also, if your LDL is a calculated value (rather than one measured directly in a lab), the fact that low-carbers tend to have low triglycerides tends to make the calculated LDL higher than it should be.

See here for a place that will calculate your LDL by the usual Friedewald equation, and also by the Iranian formula, which is more valid for low-carbers.

swhite816 said...

The main author of the first paper--Christopher Gardner--presents & interprets the results here:
http://www.youtube.com/watch?v=eREuZEdMAVo
A little long (about 1.25 hours), but he's a great presenter, worth watching/listening.