Friday, July 25, 2008
As we learn on The Cochrane Collection website, the editorial group responsible for this previously published document have withdrawn it from publication.
The reason cited for the withdrawal?
This review is withdrawn because it is very much out of date, as authors stated. None of the authors has any plans to update it.
Saturday, July 19, 2008
Thursday, July 17, 2008
First things first - the objective of the study was to compare the effectiveness and safety of weight loss diets over a two year period.
The dietary approaches included in the study:
- a low-carb diet, loosely based upon the Atkins diet, no calorie restriction
- a Mediterranean diet, calorie restricted, based on the recommendations of Dr. Willett & Dr. Skerrett (Eat, Drink & Be Healthy)
- a low-fat diet, calorie restricted, based on the American Heart Association guidelines
In addition to weighing participants each month and measuring waist circumference, the researchers measured at reporting invervals (6-months, 12-months and 24-months) total cholesterol, LDL, HDL, triglycerides, fasting blood glucose, fasting insulin, HbA1C, blood pressure, HOMA-IR, C-reactive protein, leptin, adiponectin, bilirubin, alkaline phosphatase, alanine aminotransferase and urinary ketones.
Enrolled in the study were 322 volunteers; they were provided their largest meal each day (lunch) at work, and given support and guideance about their diet throughout the study period. Of the 322 who started the trial, 95.4% completed one year, and 84.6% (272 participants) completed the 24-months - making this perhaps, the best adherence level in a dietary trial lasting two years!
So what happened? Let's look at the various outcome measures to see.
The mean weight changes among the 272 participants who completed 24 months of intervention were:
–3.3 ±4.1 kg in the low-fat group (7.3-pounds)
–4.6 ±6.0 kg in the Mediterranean-diet group (10.1-pounds)
–5.5 ±7.0 kg in the low-carbohydrate group (12.1-pounds)
Overall, in the intent to treat data (which includes even those subjects that did not complete the study) the weight loss was reported as:
–2.9 ±4.2 kg for the low-fat group (6.4-pounds)
–4.4 ±6.0 kg for the Mediterranean-diet group (9.7-pounds)
–4.7 ±6.5 kg for the low-carbohydrate group (10.3-pounds)
The reason I note the two findings is that in the media reports, the trend appears they're reporting the intent-to-treat numbers, which are lower because they include the 50 subjects that dropped out. Those who actually completed the study are the data I prefer to look at for weight loss since it accurately presents how effective the dietary approaches are when continued for two years!
-2.8 ±4.3 cm in the low-fat group
-3.5 ±5.1 cm in the Mediterranean-diet group
-3.8 ±5.2 cm in the low-carbohydrate group
The graph itself speaks volumes:
High-Sensitivity C-Reactive Protein, High-Molecular-Weight Adiponectin, and Leptin
The level of high-sensitivity C-reactive protein decreased significantly only in the Mediterranean-diet group (21%) and the low-carbohydrate group (29%), during both the weight-loss and the maintenance phases, with no significant differences among the groups in the amount of decrease.
During both the weight-loss and the maintenance phases, the level of high-molecular-weight adiponectin increased significantly in all diet groups, with no significant differences among the groups in the amount of increase.
Circulating leptin, which reflects body-fat mass, decreased significantly in all diet groups, with no significant differences among the groups in the amount of decrease; the decrease in leptin paralleled the decrease in body weight during the two phases.
Fasting Plasma Glucose, HOMA-IR, and Glycated Hemoglobin
Among the 36 participants with diabetes, only those in the Mediterranean-diet group had a decrease in fasting plasma glucose levels (32.8 mg per deciliter); this change was significantly different from the increase in plasma glucose levels among participants with diabetes in the low-fat group.
This is critically important to note - the low-fat group experienced a rise in fasting blood glucose over the course of the two years; this despite a greater calorie deficit than the other two diets, and a greater increase in physical activity! Yet, this type of diet is exactly how the ADA recommends people at risk for or diagnosed with diabetes eat, while expecting ever increasing doses of medication to cover their progressive decline in glycemic control.
It is also noteworthy that, "there was no significant change in plasma glucose level among the participants without diabetes." Basically those who did not have diabetes did not experience any change in their values over the period of the study.
What the researchers did not note in their written text of the results was this - the low-carb dieters had similar declines in their fasting blood glucose levels through month 12, followed by a progressive decline through month 24.
If we look at the data provided, we can see something important changed - the quality of the carbohydrate they consumed seems to have declined. If you look at the table providing details of the dietary intakes, one major change in the low-carb group between moth 12 and month 24 pops out - as the study progressed, the consumed less and less fiber on average, compared with their baseline intake. Now early on, that's to be expected. Later, as carbohydrate is increased - if quality whole foods are the choice - fiber typically increases!
In contrast, insulin levels decreased significantly in participants with diabetes and in those without diabetes in all diet groups, with no significant differences among groups in the amount of decrease.
Among the participants with diabetes, the decrease in HOMA-IR at 24 months was significantly greater in those assigned to the Mediterranean diet than in those assigned to the low-fat diet.
Again, in the text, the researchers do not note if there were changes in HOMA-IR in the low-carb group. There was - over the 24-month period, the HOMA-IR in those with diabetes, following the low-carb diet, declined by 1.0; in those with diabetes following the low-fat diet the decline was 0.3; and in those with diabetes following the Mediterranean diet the decline was 2.3.
The last item reported in the section was the HbA1C levels. Among the participants with diabetes, the proportion of glycated hemoglobin at 24 months decreased by:
0.4 ±1.3% in the low-fat group
0.5 ±1.1% in the Mediterranean-diet group
0.9 ±0.8% in the low-carbohydrate group
The changes were significant only in the low-carbohydrate group.
The lower HbA1C is perhaps one of the most important outcomes of this study. The diabetics, in the low-carb group, were able to lower their levels by 0.9 over the 24 months and this was significantly greater than those in the two other diets. Unfortunately the researchers did not include the baseline HbA1C for participants, so we do not know what the reduction really means.
Tests Changes in bilirubin, alkaline phosphatase, and alanine aminotransferase levels were similar among the diet groups
Alanine aminotransferase levels were significantly reduced from baseline to 24 months in the Mediterranean-diet and the low-carbohydrate groups.
The Good, Bad, and Why oh Why?
Overall, most reporting on the study today, feel the research team did a good job designing the study and executing it, many applauding the high rate of retention in the study for two years. I too am impressed that the participants remained committed to the trial, their assigned diets, and the longer-term outcome measures!
I personally would have liked more information than was published.
Key information regarding the baseline diet was not included in the data - not published items include how many calories were consumed, on average, at baseline; nor do we know how much protein, carbohydrate, fat or fiber was in the baseline dietary habits of those participating. While obviously not critical, it is 'nice to know' data.
I also would have liked to see the researchers have the courage to actually follow the Atkins dietary approach, and not make changes based on a number of assumptions.
We do not, for example, know what the outcome would be if the participants on the low-carb dietary arm had not been told to specifically choose vegetable based fats over animal fats. Atkins does not specifically state you must eat butter, but the diet allows butter. In addition, encouraging the consumption of plant-based proteins over animal proteins is another tweak that may not have had any effect, or may have had a positive or negative one. We simply do not know because the researchers encouraged plant-based protein consumption rather than leave the dietary recommendations as they are - meats, eggs, poultry, fish, tofu and such are allowed, ad libitum. [please see update below!]
The reporting in the media, as my earlier post highlights, has been quite an eye-opener. I'm not sure if those quoted realize it or not, but their reaction to the study is quite telling, especially those with the strongest vested-interests in maintaining the status quo.
In the Wall Street Journal, Robert Eckle, the past president of the American Heart Association and a professor of medicine at the University of Colorado Health Sciences Center, said he was not ready to recommend an Atkins-type low-carb diet based on the results. People on a low-carb diet increased their consumption of saturated fat, he said, which could not be good for them in the long run.
Did he even bother to read the findings?
Or maybe he was just disappointed the AHA's recommended diet - the diet recommendations the low-fat group were instructed to follow - did so poorly compared to the other two?
Did he know that the study author, Dr. Meir Stampfer of Harvard Medical School, in the same article, said "It is time to reconsider the low-fat diet as the first choice for weight loss and for cardiovascular health, it is not the best."
I think tomorrow, we'll take a fun ride through many of the quotes and opinions offered on this study!
In the meantime, what are your thoughts? Feel free to leave comments!
I received an email today from a friend who asked one of the researchers about the reference to plant-based (vegetable) fats and proteins. Dr. Shai assured him that the low carbohydrate group was not advised to consume a vegetarian low-carb diet, nor were they specifically restricted from eggs, cheese, red meat, poultry or fish. Due to dietary restriction (religious) the group would not, for instance have a cheeseburger or butter on top of their steak. Olive oil featured prominently. The participants did read the Atkins diet book. And the examples provided of the types of meals was "For example, a plate could include : fish or fried/not bread coated chicken/or red meet, broccoli and mushrooms coated with eggs, roasted eggplants, vegetable salad (peppers, cucumber, green leaves, notlettuce) with olive oil dressing.
The headlines are all over the place regarding what the results mean:
Low-Carb and Low-Fat Diets Face Off
Dr. Meir Stampfer, the study's senior author and professor of epidemiology and
nutrition at Harvard School of Public Health, told ABC News: "The low-carb diet
was the clear winner in providing the most weight loss."
The Never-Ending Diet Wars: Why Atkins Still Doesn't Beat Low-Fat Diet
"An optimal diet is one that is low in fat (because fat, whatever the type, has
9 calories per gram versus only 4 calories per gram for protein and
carbohydrates). When you eat less fat, you consume fewer calories without
having to eat less food, because the food is less dense in calories, as well as
low in refined carbohydrates."
Healthy Diets Shown to Have Benefit Despite Modest Weight Losses
In a tightly controlled dieting experiment, obese people lost an average of just
6 to 10 pounds over two years. The study, published Thursday in The New
England Journal of Medicine, was supposed to determine which of three types of
diets works best. Instead, the results highlight the difficulty of weight loss
and the fact that most diets do not work well.
More Evidence that Diets Don't Work
After two years of effort the dieters lost, on average, 6 to 10 pounds. The
study, funded in part by the Atkins Research Foundation, seemed designed to
prove that low-carb diets trump low-fat diets. But in the end, all it really
showed is that dieters can put forth tremendous effort and reap very little
Diet Study: Hold the Carbs, Not the Fats
Low-carbohydrate and so-called Mediterranean diets may be more effective than
low-fat diets, according to a major new study published in tomorrow’s New
England Journal of Medicine.
Against the Grains
Carbohydrates have taken another hit. A new study finds that a low-carb diet
results in greater weight loss and better cholesterol readings than a low-fat
regimen that promotes a lot of grains and fruits.
Diet Plans Produce Similar Results
New research shows that Mediterranean and low-carb diets are just as good and
just as safe as the low-fat diet often prescribed by doctors, a revelation that
should give people more choices in eating well.
Unrestricted Low-Carb Diet Wins Hands Down
The similar caloric deficit achieved in all diet groups suggests that a
low-carbohydrate, non–restricted-calorie diet may be optimal for those who will
not follow a restricted-calorie dietary regimen.
Atkins Diet is Safe and Far More Effective Than a Low-Fat One, Study Says
The controversial Atkins diet is just as effective and safe as a conventional
low-fat diet, a two-year study has found. Researchers found that
overweight volunteers shed more pounds on the low carbohydrate regime than they
did on an orthodox calorie-controlled diet.
Low-Carb and Mediterranean Diets May Equal Watching Fat Intake
Explain to interested patients that the study suggested low-carbohydrate and
Mediterranean diets could be as effective as the traditionally recommended
low-fat diet for weight loss.
It's amusing that each of the above headlines are all reporting on the same study!
Later today, in another post, we'll set aside the headlines and simply look at the study itself and the results.
Wednesday, July 09, 2008
Yesterday I was alerted to the newly proposed changes, open for public comment, in the Missouri Eat Smart Guidelines - standards for school lunches (and breakfast) in my state. When I first opened the document, I was not surprised by the incremental reduction of dietary fat and the push for more fiber, especially with whole grains.
What did surprise me was the absolute lack of attention to nutrient-density at each category level. Oh, there is a minimum which applies to each category - the minimums established by the USDA that establish minimum calories, fat not to exceed 30%, acceptable levels of protein, cholesterol, sodium and fiber, along with target minimums for calcium, iron, and vitamins A and C.
So the committee drafting the newly proposed "expemplary" category didn't think it wise to perhaps set the bar higher - ya know, establish benchmark minimum for other micronutrients...maybe the same ones identified as deficient in our children in Missouri?
Hey, the starting document to consider this could be the Missouri Department of Health & Senior Services (DHSS) recently published Dietary Intake Summary Report for school year 2000-2001 - in it the DHSS reported finding the vast majority (greater than 50%) of all children in the state fail to meet RDA requirements for vitamin A, iron, calcium, folate and zinc, and 25% fail to meet requirements for protein, vitamin B6 and vitamin C.
We have a serious problem with malnutrition and the best the Missouri Eat Smart Guidelines committee can come up with is stricter limits on dietary fat and increasing fiber?
Has the committee that drafted this guideline even looked at what is being served in our schools?
Columbia public schools offer this delight each day:
Smucker's PBJ Uncrustable, Pepperidge Farms Goldfish Pretzels, Rice Krispie Treat, 1% cholocate milk, baby carrots and a fruit.
Can you imagine what would be said to a parent packing such a lunch for their child?
But guess what? That lunch conforms to the standards for low-fat with just 21g of dietary fat (24% of calories) - just ignore the fact that once protein is tallied, carbohydrate accounts for 508 of the 789 calories - that's 127g of carbohydrate, or the equivalent of 32-teaspoons of sugar in a child's metabolism in one meal!
But hey, it provides 6g of fiber - above the target 5g standard, right?
The public schools have the audacity to call that abomination a nutritious lunch?
Oh, and don't get me started on the soy-based products being used in meals and that fact not being disclosed to parents, unless of course, they poke around to read the allergen lists.
Beef Tacos on the menu?
I'd expect they're made with beef, wouldn't you? Nope...they're based on an "enriched" product schools purchase - made with some beef and an ingredient listed as "VPP" - vegetable protein product - better known as soy protein.
Chicken Nuggets on the menu?
I'd expect they're breaded chicken pieces, wouldn't you? Nope...they're also based on an "enriched" product schools purchase, already prepared - made with some chicken and an ingredient listed as ISP - isolated soya protein.
Think it can't get worse?
I don't think schools do much more than open a can, heat and serve these days - just reading through the spreadsheets available online makes that pretty clear - almost everything sold in school breakfast and lunches are convenience foods, from various vendors, that are nutritionally bankrupt, but easy to heat and serve.
If a parent were to habitually feed their child that crap, at the very least they'd be chastized as irresponsible - yet this is how the schools operate each day, serving what can only be called food-garbage each day and they have audacity to label them "healthful" and nutritious.
When you have a chance, read through the proposed Missouri Eat Smart Guidelines, then let the committee know what you think in the open public comments!
If people don't start speaking up, and demanding truly nutrient-dense meals for their children, it's only going to get worse!