Just in: results of new Low-Carb diet studies!

From The Omnivore

By Anthony Colpo.

May 19, 2004.

The May 18, 2004 issue of the Annals of Internal Medicine features two new low-carbohydrate-vs-low-fat diet trial reports. I have summarized the findings for readers, and thrown in my ten cents worth after discussing each study. For those who would like to access the original full-text articles, just click on the hyperlinks provided.

Study 1 Atkins versus low-fat diet

William Yancy and his colleagues randomized 120 overweight volunteers to follow either the Atkins Diet or a low-fat, high-carbohydrate diet. The intervention for both groups included group meetings which took place at an outpatient clinic twice monthly for 3 months, then monthly for 3 months. The meetings typically lasted 1 hour and consisted of diet instruction, supportive counseling, questionnaires, and biomedical measurements.

Participants were encouraged to exercise for 30 minutes at least 3 times weekly, but no formal exercise program or incentives were provided.

Following the guidelines presented in Dr. Atkins' New Diet Revolution and additional handouts, trained research staff instructed participants to restrict intake of carbohydrates to less than 20 g/d. The low-carb participants were permitted unlimited amounts of meat, fowl, eggs, fish, and shellfish, 4 oz of hard cheese, 2 cups of salad vegetables (such as lettuce, spinach, or celery), and 1 cup of low-carbohydrate vegetables (such as broccoli, cauliflower, or squash) daily.

When participants were halfway to their goal body weight (determined at the week 10 visit with assistance from research personnel), they were advised to add approximately 5 g of carbohydrates to their daily intake each week until they reached a level at which they could maintain their body weight.

The low-carbohydrate diet group also received daily Atkins Nutritionals, Inc supplements (multivitamin, essential oils, diet formulation, and chromium picolinate; for a list of the composition of these supplements, see below)

Using a commonly available booklet and additional handouts, a registered dietitian instructed participants in the low-fat group to consume less than 30% of calories as fat, less than 10% of calories as saturated fat, and to eat 500 to 1000 calories less than the participant's calculated energy intake for weight maintenance (body weight in pounds x 10).

Food records collected at each visit from a subsample of participants indicate that the low-carbohydrate diet group consumed a mean 30g of carbohydrates, 98g of protein, and 111g of fat daily. The low-fat diet group consumed 198g of carbohydrates, 71g of protein, and 49g of fat daily.

Despite the fact that the low-fat diet group received counseling to restrict overall calorie intake whilst the low-carbohydrate diet group received counseling to restrict intake of carbohydrates only, the estimated daily energy intake was 1461 calories in the low-carbohydrate diet group and 1502 calories in the low-fat diet group.

Results

Dropout rates were higher in the low-fat group; forty-five (76%) of the 59 participants originally assigned to the low-carbohydrate diet group and 34 (57%) of the 60 participants assigned to the low-fat diet group completed the study.

Over 24 weeks, the mean weight loss in the low-carbohydrate diet group was almost twice as great as that in the low-fat group; 12.0 kg versus 6.5 kg, respectively. The proportion of this weight loss derived from fat was 9.4 kg in the low-carbohydrate diet group and 4.8 kg for the low-fat diet group.

For those who still insist that the weight reduction seen on low-carb diets is derived primarily from water loss, the mean change in total body water was –2.4 kg in the low-carbohydrate diet group and –1.8 kg in the low-fat diet group, a negligible difference.

In addition to experiencing greater average weight loss and lower attrition, a higher proportion of the low-carb participants lost greater than 10% of their initial body weight; 61% versus 23%, respectively.

The low-carbohydrate diet group also showed more beneficial changes in blood triglyceride levels and HDL levels than did the low-fat diet group.(1)

Adverse Effects

Several adverse effects occurred more frequently in the low-carbohydrate diet group than in the low-fat diet group, including constipation 68% vs. 35%, headache (60% vs. 40%), bad breath (38% vs. 8%), muscle cramps (35% vs. 7%), diarrhea (23% vs. 7%), general weakness (25% vs. 8%), and rash (13% vs. 0%). A 53-year-old male in the low-carbohydrate diet group who had a family history of early heart disease developed chest pain near the end of the study, and coronary heart disease was subsequently diagnosed. During the study, this participant lost 16 kg, his serum LDL cholesterol level decreased by 0.75 mmol/L (29 mg/dL), and his serum HDL cholesterol level increased by 0.21 mmol/L (8 mg/dL).

Comments: A while back, I read commentary on the preliminary data of this study by a couple of anti-low-carb figures who claimed the addition of vitamin and fish oil supplements provided an unfair advantage to the low-carb group. Personally, I believe both groups should have been given the same supplements as a routine measure to ensure that this was purely a diet comparison. As it stands, this study was a comparison of the Atkins diet plus supplements versus a low-fat diet. Nonetheless, if any of the aforementioned jokers truly believe that the ingredients in the supplements provided (see reference 2 below) could produce a 5.5kg weight loss (the difference between the low- and high-carb groups), then they might be interested in some prime swamp-, er, I mean, prime real estate I've got for sale at a bargain price...

The side effects noted in the low-carb group are worthy of further mention. No doubt the incidence of constipation could be reduced by increasing the miniscule intake of low-carb plant foods that was prescribed in this study. The participants could have obtained far more roughage than that provided in 3 piddling cups of veggies without endangering their low-carb status. The greater incidence of headache and general weakness seems to me symptomatic of low-blood sugar episodes, which is going to be a reality for many people when they consume only 30g of carbs per day. Many folks will also have to get used to the idea of ketosis breath if they are going to opt for ketogenic low-carb plans. I have nothing but the greatest admiration and respect for the late Dr. Atkins, but as I have said several times before, many people will benefit from keeping their carb intakes a little higher than the average level seen in this study.

Despite these drawbacks, it is interesting to see that a notably greater number of participants dropped out in the low-fat group. This parallels the findings of almost every low-carb vs low-fat study reporting drop-outs that I have come across.

This study was financed by a research grant from the Robert C. Atkins Foundation, New York, NY. No doubt this will bring charges from the anti-low-carb crowd of researcher bias, despite at least one of the lead researchers publicly admitting that he had fully expected the Atkins diet to perform poorly. Eric Westman told BBC reporters: "We didn't expect that the diet would do very well. We weren't really expecting to find much weight loss at all. It was also a very extreme diet so that we thought people would have difficulty staying on it."(3) According to a disclosure statement in the Annals paper, "Investigators at Duke University conducted the study and maintained exclusive control of all data and analyses. The funding source had no involvement in the recruitment of participants; study interventions; collection, analysis, or interpretation of the data; or preparation or review of the manuscript."

Study 2 Fat loss in Philly

The second paper appearing in the Annals reported on a study conducted by researchers from Philadelphia Veterans Affairs Medical Center. Readers may remember the 6-month report of this study as one of two papers that attracted widespread media attention when they appeared in the New England Journal of Medicine this time last year. Well, the researchers involved decided to see who was still standing (figuratively speaking, of course) among the participants of this trial after one year, and to report their progress.

Of the 132 indivdiuals who commenced the study, 45 dropped out after 1 year; 20 persons in the low-carbohydrate group and 25 in the conventional low-fat diet group.

Those who read the NEJM report from last year will know that after 6 months the low-carb group lost an average 5.8kg, compared to only 1.9kg on the high-carb, low-fat diet. After 1-year, the average weight loss was 5.1kg in the low-carbohydrate group and 3.1kg in the high-carb diet group. The difference in weight loss between the 2 diet groups was not statistically significant.

HDL levels increased and triglyceride levels decreased more in the low-carbohydrate group than in the high-carb diet group, an effect that was independent of weight loss.

The difference in blood glucose levels and insulin sensitivity between diet groups by 1 year was not significant, although hemoglobin A1c levels in the portion of subjects with diabetes decreased more in the low-carbohydrate group. Two persons on the low-carbohydrate diet and 4 on the conventional diet developed diabetes after 1 year.

Adverse Reactions

One person on the low-carbohydrate diet was hospitalized with noncardiac chest pain during the third month of the study. Two persons in the low-carbohydrate group died, including one who died of complications of hyperosmolar coma 5 months into the study and another who had severe ischemic cardiomyopathy and died suddenly 10 months after study enrollment. Laboratory values obtained 14 days before this person's death showed no electrolyte abnormalities.

Comments: Triglyceride, HDL cholesterol, and hemoglobin A1c levels showed greater improvements among the low-carb diet group at 12 months, but no statistically significant difference in weight loss was evident.

A look at the dietary composition data shows why the low-carb diet produced such a lacklustre result in weight loss during the last six months of the study; by 12 months, most of the subjects were no longer following a low-carb diet! Average carb intake was 120g, while protein had declined from baseline, from 84g to an anaemic 73g. Compliance with the diet, evidently, was poor.

Nonetheless, this raises an important point. The study by Gary Foster, et al, which also appeared in the May 22, 2003 issue of the NEJM, showed a deterioration in compliance among both the low-carb and low-fat groups. While the low-carb group showed notably greater weight loss at the 6-month point, after 12 months the weight loss difference between the two groups was again not significant.

Critics of low-carb diets have jumped on these observations, claiming that they prove low-carb diets are hard to adhere to. If this is the argument they are going to stick with, they better realize that published head-to-head comparisons with low-carb diets indicate that low-fat diets are even harder to stick to.

The truth is, a great many people are going to find the going tough no matter what diet they choose to follow. Personally, I find sticking to a low-carb diet requires about as much discipline as lying on a tropical beach, and numerous other low-carbers I have corresponded with have shared similar sentiments. Still, for many people, adopting a low-carbohydrate diet will mean a considerable departure from their usual habits, and the going will not be easy.

As research shows that behavioral modifications can significantly affect the attrition and success rate of one's weight loss efforts, the time is probably ripe for some serious, in-depth research into this aspect of dieting.

Our hunter-gatherer ancestors did not have the option of eating highly-processed, refined carbohydrate-rich junk, nor did they have the option of sitting on their butts all day. They had to get up and expend energy in their search for food - if not, they starved! Not surprisingly, our Paleolithic forebears were untroubled by obesity.

The reason so many of us are in such attrocious shape nowadays is because we are presented with choices not available to our ancestors; the choice to eat wholesome filling food, or nutrient-depleted, craving-inducing crap; the choice to engage in regular physical activity, or to succumb to mechanization's ability to completely remove the need for physical activity from of our lives.

It's going to take a lot more than hyperbolic weight loss claims to convince the bulk of the population to opt for the healthier of these choices on a long-term basis...

References

1. Yancy WS, et al. A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia: A Randomized, Controlled Trial. Annals of Internal Medicine, 2004; 140: 769-777.

2. Supplements (provided by Atkins Nutritionals, Inc., New York, NY):

Multivitamin formula (administered daily as 6 capsules): vitamin A as acetate (3000 IU); vitamin A as ß-carotene with mixed carotenoids (1200 IU); vitamin C (360 mg); vitamin D3 (400 IU); vitamin E (300 IU); vitamin B1 (50 mg); vitamin B2 (50 mg); niacin (40 mg); vitamin B6 (50 mg); folate (1600 mg); vitamin B12 (800 mcg); vitamin K (10 µg); biotin (600 µg); pantothenic acid (120 mg); calcium (500 mg); magnesium (250 mg); zinc (50 mg); selenium (200 µg); manganese (10 mg); chromium (600 µg); molybdenum (60 µg); potassium (20 mg); inositol hexanicotinate (100 mg); choline bitartrate (100 mg); para-amino benzoic acid (100 mg); vanadyl (80 µg); N-acetyl-l-cysteine (120 mg); pantethine (150 mg); quercetin (100 mg); boron (2 mg); grapeseed extract (40 mg); green tea (80 mg); and lecithin extracts, garlic, arginine, licorice, bromelain, pantethine, spirulina, inulin, lactoferrin, bioperine, and acidophilus, in unspecified amounts.

Essential oil formula (administered daily as 3 capsules): flaxseed oil (1200 mg), borage seed oil (1200 mg), fish oil (1200 mg), vitamin E (15 IU).

Diet formula (administered daily as 6 capsules): citrin (2700 mg), chromium (1200 µg), soy extract (9000 mg), methionine (1500 mg), L-carnitine (3000 mg), vitamin B6 (120 mg), pantethine (120 mg), asparagus (300 mg), parsley (300 mg), kelp (120 mg), spirulina (300 mg), potassium citrate (594 mg), magnesium (360 mg), L-glutamine (450 mg), dl-phenylalanine (900 mg), L-tyrosine (450 mg), piperine (30 mg).

3. The Atkins Diet. BBC Two, Jan 22, 2004.
http://www.bbc.co.uk/science/horizon/2004/atkinstrans.shtml

4. Stern L, et al. The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One-Year Follow-up of a Randomized Trial. Annals of Internal Medicine, 2004; 140: 778-785.

5. Samaha FF, et al. A low-carbohydrate diet as compared with a low fat diet in severe obesity. New England Journal of Medicine, May 22, 2003; 348: 2074-2081.

Anthony Colpo is an independent researcher and certified fitness consultant with 20 years' experience in the physical conditioning arena. To contact: contact@theomnivore.com

Disclaimer: This article is presented for information purposes only and is not intended as medical advice. Persons with medical conditions should institute dietary changes whilst being monitored by a competent medical practitioner.

© Anthony Colpo 2004. Copyright information:

Any articles on this website authored by Anthony Colpo may be reproduced for non-commercial purposes only, providing full credit is given to the author, and that the website name www.theomnivore.com is cited. A hyperlink would also be greatly appreciated. Those wishing to reproduce articles for commercial purposes should e-mail: contact@theomnivore.com

A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia

From the Annals of Internal Medicine

A Randomized, Controlled Trial

William S. Yancy, Jr., MD, MHS; Maren K. Olsen, PhD; John R. Guyton, MD; Ronna P. Bakst, RD; and Eric C. Westman, MD, MHS

18 May 2004 | Volume 140 Issue 10 | Pages 769-777

Background: Low-carbohydrate diets remain popular despite a paucity of scientific evidence on their effectiveness.

Objective: To compare the effects of a low-carbohydrate, ketogenic diet program with those of a low-fat, low-cholesterol, reduced-calorie diet.

Design: Randomized, controlled trial.

Setting: Outpatient research clinic.

Participants: 120 overweight, hyperlipidemic volunteers from the community.

Intervention: Low-carbohydrate diet (initially, <20 g of carbohydrate daily) plus nutritional supplementation, exercise recommendation, and group meetings, or low-fat diet (<30% energy from fat, <300 mg of cholesterol daily, and deficit of 500 to 1000 kcal/d) plus exercise recommendation and group meetings.

Measurements: Body weight, body composition, fasting serum lipid levels, and tolerability.

Results: A greater proportion of the low-carbohydrate diet group than the low-fat diet group completed the study (76% vs. 57%; P = 0.02). At 24 weeks, weight loss was greater in the low-carbohydrate diet group than in the low-fat diet group (mean change, –12.9% vs. –6.7%; P < 0.001). Patients in both groups lost substantially more fat mass (change, –9.4 kg with the low-carbohydrate diet vs. –4.8 kg with the low-fat diet) than fat-free mass (change, –3.3 kg vs. –2.4 kg, respectively). Compared with recipients of the low-fat diet, recipients of the low-carbohydrate diet had greater decreases in serum triglyceride levels (change, –0.84 mmol/L vs. –0.31 mmol/L [–74.2 mg/dL vs. –27.9 mg/dL]; P = 0.004) and greater increases in high-density lipoprotein cholesterol levels (0.14 mmol/L vs. –0.04 mmol/L [5.5 mg/dL vs. –1.6 mg/dL]; P < 0.001). Changes in low-density lipoprotein cholesterol level did not differ statistically (0.04 mmol/L [1.6 mg/dL] with the low-carbohydrate diet and –0.19 mmol/L [–7.4 mg/dL] with the low-fat diet; P = 0.2). Minor adverse effects were more frequent in the low-carbohydrate diet group.

Limitations: We could not definitively distinguish effects of the low-carbohydrate diet and those of the nutritional supplements provided only to that group. In addition, participants were healthy and were followed for only 24 weeks. These factors limit the generalizability of the study results.

Conclusions: Compared with a low-fat diet, a low-carbohydrate diet program had better participant retention and greater weight loss. During active weight loss, serum triglyceride levels decreased more and high-density lipoprotein cholesterol level increased more with the low-carbohydrate diet than with the low-fat diet.

The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One-Year Follow-up of a Randomized Trial

From the Annals of Internal Medicine

Linda Stern, MD; Nayyar Iqbal, MD; Prakash Seshadri, MD; Kathryn L. Chicano, CRNP; Denise A. Daily, RD; Joyce McGrory, CRNP; Monica Williams, BS; Edward J. Gracely, PhD; and Frederick F. Samaha, MD

18 May 2004 | Volume 140 Issue 10 | Pages 778-785

Background: A previous paper reported the 6-month comparison of weight loss and metabolic changes in obese adults randomly assigned to either a low-carbohydrate diet or a conventional weight loss diet.

Objective: To review the 1-year outcomes between these diets.

Design: Randomized trial.

Setting: Philadelphia Veterans Affairs Medical Center.

Participants: 132 obese adults with a body mass index of 35 kg/m2 or greater; 83% had diabetes or the metabolic syndrome.

Intervention: Participants received counseling to either restrict carbohydrate intake to <30 g per day (low-carbohydrate diet) or to restrict caloric intake by 500 calories per day with <30% of calories from fat (conventional diet).

Measurements: Changes in weight, lipid levels, glycemic control, and insulin sensitivity.

Results: By 1 year, mean (±SD) weight change for persons on the low-carbohydrate diet was –5.1 ± 8.7 kg compared with –3.1 ± 8.4 kg for persons on the conventional diet. Differences between groups were not significant (–1.9 kg [95% CI, –4.9 to 1.0 kg]; P = 0.20). For persons on the low-carbohydrate diet, triglyceride levels decreased more (P = 0.044) and high-density lipoprotein cholesterol levels decreased less (P = 0.025). As seen in the small group of persons with diabetes (n = 54) and after adjustment for covariates, hemoglobin A1c levels improved more for persons on the low-carbohydrate diet. These more favorable metabolic responses to a low-carbohydrate diet remained significant after adjustment for weight loss differences. Changes in other lipids or insulin sensitivity did not differ between groups.

Limitations: These findings are limited by a high dropout rate (34%) and by suboptimal dietary adherence of the enrolled persons.

Conclusion: Participants on a low-carbohydrate diet had more favorable overall outcomes at 1 year than did those on a conventional diet. Weight loss was similar between groups, but effects on atherogenic dyslipidemia and glycemic control were still more favorable with a low-carbohydrate diet after adjustment for differences in weight loss.

Is a calorie a calorie?

American Journal of Clinical Nutrition, Vol. 79, No. 5, 899S-906S, May 2004
© 2004 American Society for Clinical Nutrition

Andrea C Buchholz and Dale A Schoeller

From the Department of Nutritional Sciences, University of Wisconsin-Madison

The aim of this review was to evaluate data regarding potential thermodynamic mechanisms for increased rates of weight loss in subjects consuming diets high in protein and/or low in carbohydrate. Studies that compared weight loss and energy expenditure in adults consuming diets high in protein and/or low in carbohydrate with those in adults consuming diets low in fat were reviewed. In addition, studies that measured the metabolizable energy of proteins, fats, and carbohydrates were reviewed. Diets high in protein and/or low in carbohydrate produced an 2.5-kg greater weight loss after 12 wk of treatment. Neither macronutrient-specific differences in the availability of dietary energy nor changes in energy expenditure could explain these differences in weight loss. Thermodynamics dictate that a calorie is a calorie regardless of the macronutrient composition of the diet. Further research on differences in the composition of weight loss and on the influence of satiety on compliance with energy-restricted diets is needed to explain the observed increase in weight loss with diets high in protein and/or low in carbohydrate.

Effect of a High Saturated Fat and No-Starch Diet

Effect of a High Saturated Fat and No-Starch Diet on Serum Lipid Subfractions in Patients With Documented Atherosclerotic Cardiovascular Disease

JAMES H. HAYS, MD; ANGELA DISABATINO, RN, MS; ROBERT T. GORMAN, PHD;
SIMI VINCENT, PHD, MD; AND MICHAEL E. STILLABOWER, MD

Full article: Mayo Clinic [PDF file]

New Study Suggests Calories May Not Count

CAMBRIDGE, Mass., Oct. 14 /PRNewswire/ -- One of the most controversial aspects of low-carbohydrate diets such as the Atkins Nutritional Approach™ is their rejection of the tyranny of calorie counting. Critics of these plans claim that the reason people lose weight on low-carb diets is the same reason they lose weight on any other diet: they actually consume fewer calories, presumably because they are bored with monotony of all that steak. Now, a new study by Harvard researchers suggests that these critics are wrong and that people lose at least as much weight on a low-carbohydrate diet than those on a low-fat diet, even when they consume significantly more calories every day.

Last May two studies were published in the New England Journal of Medicine that showed the benefits of low-carbohydrate diets, but they left some open questions. "Some people have argued that if there is a difference between low- fat and low-carb diets as some studies have shown, it's due to caloric restriction because people are either bored and thus eat less or people are satiated and thus eat less," says Penelope Greene, a nutritionist at the Harvard School for Public Health and chief author of the new study. "My own view is that if it's boring then that's a particular concern, because that's not a diet that can be maintained. If it's caloric restriction because it's satiating and people are happy, I'm not sure that that's necessarily a bad thing. That seems like a good thing."

To prove that something more than mere caloric restriction is the reason that low-carb diets work, Greene and her colleagues had to improve on the previous "free-feeding" studies. In these experiments, subjects were randomly divided into two groups, and told to follow either a low-fat or a low-carb diet on their own. The researchers did not know how much the subjects actually consumed, which meant that it was possible that the low-carb eaters were leaving food uneaten on their plates. Greene and her colleagues, Walter Willett, Juniper Devicis and Antoine Skaf set out to perform a more carefully controlled, controlled-feeding experiment in which the subjects would be given prepared meals with portions weighed to the nearest gram.

Controlled-feeding experiments are notoriously difficult, Greene explains. "A lot of people didn't think we could do this," she says. After running the pilot study, which consisted of 21 subjects, she understands why. For several months she was putting in 10- to 15-hour days, seven days a week, supervising food preparation, color coding meals, and keeping records. The researchers contracted out the preparation of the food to an upscale Italian restaurant in Cambridge, MA, Ristorante Marino. "They were very used to doing catering," she says, "but not in weighing food to the nearest gram." Furthermore, they had to produce two different preparations of most foods -- low-fat and low-carb -- at five different calorie levels.

The pilot study, which was performed last fall, consisted of three sets of seven subjects each. "This was a very motivated group," Greene explains. "They were all over-fifty, overweight and overly scared. We had hundreds of people who wanted to enroll." The subjects would pick up their meals every evening and return the uneaten portion from the previous day. "There was very, very little of that," Greene says. "What I got back were little dregs of lettuce, literally."

The first group was fed a low-fat diet, consisting of 1,500 calories a day for women and 1,800 calories a day for men. The second group was given a low-carbohydrate diet, but the same number of calories. To test the hypothesis that the weight loss is not due to caloric restriction, the third group was also fed a low-carb diet, but 1,800 calories a day for women and 2,100 calories a day for men. Over the 12-week course of the study this group consumed 25,000 extra calories. According to many diet books, 3,500 calories equals one pound, which means that the third group should have lost 7 pounds less than the other two groups. In fact, to within statistical error the subjects in all three groups lost more or less the same weight. "I think this was the most surprising thing, and made this very much worth doing," Greene said. "Keep in mind that there are people who would have argued that the second group should have not done as well because of all the fat they ate."

Greene is quick to point out that this was only a pilot study, though "probably the most elaborate pilot study I have ever heard of. The purpose of the experiment was to see if under these controlled conditions there was really anything to warrant a larger study. And the answer is yes, certainly."

Source: Yahoo

Low-Carb Diets Are Working, Study Says

By DANIEL Q. HANEY, AP Medical Editor

FORT LAUDERDALE, Fla. - The dietary establishment has long argued it's impossible, but a new study offers intriguing evidence for the idea that people on low-carbohydrate diets can actually eat more than folks on standard lowfat plans and still lose weight.

Perhaps no idea is more controversial in the diet world than the contention — long espoused by the late Dr. Robert Atkins — that people on low-carbohydrate diets can consume more calories without paying a price on the scales.

Over the past year, several small studies have shown, to many experts' surprise, that the Atkins approach actually does work better, at least in the short run. Dieters lose more than those on a standard American Heart Association plan without driving up their cholesterol levels, as many feared would happen.

Skeptics contend, however, that these dieters simply must be eating less. Maybe the low-carb diets are more satisfying, so they do not get so hungry. Or perhaps the food choices are just so limited that low-carb dieters are too bored to eat a lot.

Now, a small but carefully controlled study offers a strong hint that maybe Atkins was right: People on low-carb, high-fat diets actually can eat more.

The study, directed by Penelope Greene of the Harvard School of Public Health and presented at a meeting here this week of the American Association for the Study of Obesity, found that people eating an extra 300 calories a day on a very low-carb regimen lost just as much during a 12-week study as those on a standard lowfat diet.

Over the course of the study, they consumed an extra 25,000 calories. That should have added up to about seven pounds. But for some reason, it did not.

"There does indeed seem to be something about a low-carb diet that says you can eat more calories and lose a similar amount of weight," Greene said.

That strikes at one of the most revered beliefs in nutrition: A calorie is a calorie is a calorie. It does not matter whether they come from bacon or mashed potatoes; they all go on the waistline in just the same way.

Not even Greene says this settles the case, but some at the meeting found her report fascinating.

"A lot of our assumptions about a calorie is a calorie are being challenged," said Marlene Schwartz of Yale. "As scientists, we need to be open-minded."

Others, though, found the data hard to swallow.

"It doesn't make sense, does it?" said Barbara Rolls of Pennsylvania State University. "It violates the laws of thermodynamics. No one has ever found any miraculous metabolic effects."

In the study, 21 overweight volunteers were divided into three categories: Two groups were randomly assigned to either lowfat or low-carb diets with 1,500 calories for women and 1,800 for men; a third group was also low-carb but got an extra 300 calories a day.

The study was unique because all the food was prepared at an upscale Italian restaurant in Cambridge, Mass., so researchers knew exactly what they ate. Most earlier studies simply sent people home with diet plans to follow as best they could.

Each afternoon, the volunteers picked up that evening's dinner, a bedtime snack and the next day's breakfast and lunch. Instead of lots of red meat and saturated fat, which many find disturbing about low-carb diets, these people ate mostly fish, chicken, salads, vegetables and unsaturated oils.

"This is not what people think of when they think about an Atkins diet," Greene said. Nevertheless, the Atkins organization agreed to pay for the research, though it had no input into the study's design, conduct or analysis.

Everyone's food looked similar but was cooked to different recipes. The low-carb meals were 5 percent carbohydrate, 15 percent protein and 65 percent fat. The rest got 55 percent carbohydrate, 15 percent protein and 30 percent fat.

In the end, everyone lost weight. Those on the lower-cal, low-carb regimen took off 23 pounds, while people who got the same calories on the lowfat approach lost 17 pounds. The big surprise, though, was that volunteers getting the extra 300 calories a day of low-carb food lost 20 pounds.

"It's very intriguing, but it raises more questions than it answers," said Gary Foster of the University of Pennsylvania. "There is lots of data to suggest this shouldn't be true."

Greene said she can only guess why the people getting the extra calories did so well. Maybe they burned up more calories digesting their food.

Dr. Samuel Klein of Washington University, the obesity organization's president, called the results "hard to believe" and said perhaps the people eating more calories also got more exercise or they were less apt to cheat because they were less hungry.

EDITOR'S NOTE: Medical Editor Daniel Q. Haney is a special correspondent for The Associated Press.

Source: yahoo.com

A Randomized Trial of a Low-Carbohydrate Diet for Obesity

Volume 348:2082-2090 May 22, 2003 Number 21

Gary D. Foster, Ph.D., Holly R. Wyatt, M.D., James O. Hill, Ph.D., Brian G. McGuckin, Ed.M., Carrie Brill, B.S., B. Selma Mohammed, M.D., Ph.D., Philippe O. Szapary, M.D., Daniel J. Rader, M.D., Joel S. Edman, D.Sc., and Samuel Klein, M.D.

ABSTRACT

Background
Despite the popularity of the low-carbohydrate, high-protein, high-fat (Atkins) diet, no randomized, controlled trials have evaluated its efficacy.

Methods
We conducted a one-year, multicenter, controlled trial involving 63 obese men and women who were randomly assigned to either a low-carbohydrate, high-protein, high-fat diet or a low-calorie, high-carbohydrate, low-fat (conventional) diet. Professional contact was minimal to replicate the approach used by most dieters.

Results
Subjects on the low-carbohydrate diet had lost more weight than subjects on the conventional diet at 3 months (mean [±SD], –6.8±5.0 vs. –2.7±3.7 percent of body weight; P=0.001) and 6 months (–7.0±6.5 vs. –3.2±5.6 percent of body weight, P=0.02), but the difference at 12 months was not significant (–4.4±6.7 vs. –2.5±6.3 percent of body weight, P=0.26). After three months, no significant differences were found between the groups in total or low-density lipoprotein cholesterol concentrations. The increase in high-density lipoprotein cholesterol concentrations and the decrease in triglyceride concentrations were greater among subjects on the low-carbohydrate diet than among those on the conventional diet throughout most of the study. Both diets significantly decreased diastolic blood pressure and the insulin response to an oral glucose load.

Conclusions
The low-carbohydrate diet produced a greater weight loss (absolute difference, approximately 4 percent) than did the conventional diet for the first six months, but the differences were not significant at one year. The low-carbohydrate diet was associated with a greater improvement in some risk factors for coronary heart disease. Adherence was poor and attrition was high in both groups. Longer and larger studies are required to determine the long-term safety and efficacy of low-carbohydrate, high-protein, high-fat diets.

Source Information
From the University of Pennsylvania School of Medicine, Philadelphia (G.D.F., B.G.M., P.O.S., D.J.R.); University of Colorado Health Sciences Center, Denver (H.R.W., J.O.H., C.B.); Washington University School of Medicine, St. Louis (B.S.M., S.K.); and Thomas Jefferson University, Philadelphia (J.S.E.).

Source: New England Journal of Medicine

A Low-Carbohydrate as Compared with a Low-Fat Diet in Severe Obesity

Volume 348:2074-2081 May 22, 2003 Number 21

Frederick F. Samaha, M.D., Nayyar Iqbal, M.D., Prakash Seshadri, M.D., Kathryn L. Chicano, C.R.N.P., Denise A. Daily, R.D., Joyce McGrory, C.R.N.P., Terrence Williams, B.S., Monica Williams, B.S., Edward J. Gracely, Ph.D., and Linda Stern, M.D.

ABSTRACT

Background
The effects of a carbohydrate-restricted diet on weight loss and risk factors for atherosclerosis have been incompletely assessed.

Methods
We randomly assigned 132 severely obese subjects (including 77 blacks and 23 women) with a mean body-mass index of 43 and a high prevalence of diabetes (39 percent) or the metabolic syndrome (43 percent) to a carbohydrate-restricted (low-carbohydrate) diet or a calorie- and fat-restricted (low-fat) diet.

Results
Seventy-nine subjects completed the six-month study. An analysis including all subjects, with the last observation carried forward for those who dropped out, showed that subjects on the low-carbohydrate diet lost more weight than those on the low-fat diet (mean [±SD], –5.8±8.6 kg vs. –1.9±4.2 kg; P=0.002) and had greater decreases in triglyceride levels (mean, –20±43 percent vs. –4±31 percent; P=0.001), irrespective of the use or nonuse of hypoglycemic or lipid-lowering medications. Insulin sensitivity, measured only in subjects without diabetes, also improved more among subjects on the low-carbohydrate diet (6±9 percent vs. –3±8 percent, P=0.01). The amount of weight lost (P<0.001) and assignment to the low-carbohydrate diet (P=0.01) were independent predictors of improvement in triglyceride levels and insulin sensitivity.

Conclusions
Severely obese subjects with a high prevalence of diabetes or the metabolic syndrome lost more weight during six months on a carbohydrate-restricted diet than on a calorie- and fat-restricted diet, with a relative improvement in insulin sensitivity and triglyceride levels, even after adjustment for the amount of weight lost. This finding should be interpreted with caution, given the small magnitude of overall and between-group differences in weight loss in these markedly obese subjects and the short duration of the study. Future studies evaluating long-term cardiovascular outcomes are needed before a carbohydrate-restricted diet can be endorsed.

Source Information
From the Philadelphia Veterans Affairs Medical Center (F.F.S., N.I., K.L.C., D.A.D., J.M., T.W., M.W., L.S.); the Department of Medicine, Division of Cardiology (F.F.S.), and the Department of Medicine, Division of Endocrinology (N.I., P.S.), University of Pennsylvania Medical Center; and the Department of Family, Community, and Preventive Medicine, Drexel University College of Medicine (E.J.G.) — all in Philadelphia.

Source: New England Journal of Medicine

Atkins diet 'is beneficial and twice as effective as rivals'

The controversial Atkins diet, which severely restricts carbohydrates in favour of unlimited amounts of fat and protein, is twice as effective as conventional diets at shedding excess pounds, new research has shown.

In a six-month trial, volunteers following the regime lost twice as much weight as those on more traditional low-calorie, high-carbohydrate diets.

And despite fears that the bestselling diet could be harmful in the long term, researchers found that the diet protected against heart disease by increasing levels of "good" cholesterol.

Full article: telegraph.co.uk

Hepatic de novo lipogenesis in normoinsulinemic and hyperinsulinemic subjects consuming high-fat, low-carbohydrate and low-fat, high-carbohydrate isoenergetic diets

"Compared with baseline, consumption of the high-fat, low-carbohydrate diet did not affect triacylglycerol concentrations. However, after the low-fat, high-carbohydrate diet, triacylglycerols increased significantly and DNL was 5–6-fold higher than in normoinsulinemic subjects consuming a high-fat diet. The increase in triacylglycerol after the low-fat, high-carbohydrate diet was correlated with fractional DNL (P < 0.01), indicating that subjects with high DNL had the greatest increase in triacylglycerols.

Conclusions: These results support the concept that both hyperinsulinemia and a low-fat diet increase DNL, and that DNL contributes to hypertriglyceridemia."

American Journal of Clinical Nutrition, Vol. 77, No. 1, 43-50, January 2003

Full article: American Journal of Clinical Nutrition

Trial of a Very Low Carbohydrate Diet

A Randomized Trial Comparing a Very Low Carbohydrate Diet and a Calorie-Restricted Low Fat Diet on Body Weight and Cardiovascular Risk Factors in Healthy Women

BONNIE J. BREHM, RANDY J. SEELEY, STEPHEN R. DANIELS, AND DAVID A. D’ALESSIO
University of Cincinnati and Children’s Hospital Medical Center, Cincinnati, Ohio 45221

Untested alternative weight loss diets, such as very low carbohydrate diets, have unsubstantiated efficacy and the potential to adversely affect cardiovascular risk factors. Therefore, we designed a randomized, controlled trial to determine the effects of a very low carbohydrate diet on body composition and cardiovascular risk factors. Subjects were randomized to 6 months of either an ad libitum very low carbohydrate diet or a calorie-restricted diet with 30% of the calories as fat.
Anthropometric and metabolic measures were assessed at baseline, 3 months, and 6 months. Fifty-three healthy, obese female volunteers (mean body mass index, 33.6 +/- 0.3 kg/m2) were randomized; 42 (79%) completed the trial. Women on both diets reduced calorie consumption by comparable amounts at 3 and 6 months. The very low carbohydrate diet group lost more weight (8.5 +/- 1.0 vs. 3.9 +/- 1.0 kg; P < 0.001) and more body fat (4.8+/-0.67 vs. 2.0+/-0.75 kg; P<0.01) than the low fat diet group. Mean levels of blood pressure, lipids, fasting glucose, and insulin were within normal ranges in both groups at baseline. Although all of these parameters improved over the course of the study, there were no differences observed between the two diet groups at 3 or 6 months. Beta-Hydroxybutyrate increased significantly in the very low carbohydrate group at 3 months (P = 0.001). Based on these data, a very low carbohydrate diet is more effective than a low fat diet for short-term weight loss and, over 6 months, is not associated with deleterious effects on important cardiovascular risk factors in healthy women. (J Clin Endocrinol Metab 88: 1617–1623, 2003)

Full text article: endo-society.org [PDF File]

BBC Diet Trials Results

Official site: BBC Diet Trials Results

Quote Barry Groves, PhD - Second Opinions:

+

These snippets from Low-Carb in the UK with permission from the author Barry Groves, PhD, Author of "Eat Fat, Get Thin!" and Second Opinions.

Effects of a low-carbohydrate diet on overweight adolescents

J Pediatr 2003 Mar;142(3):253-8

Sondike SB, Copperman N, Jacobson MS.

Division of Adolescent Medicine, Schneider Children's Hospital, New Hyde Park, New York.

OBJECTIVES: To compare the effects of a low-carbohydrate (LC) diet with those of a low-fat (LF) diet on weight loss and serum lipids in overweight adolescents.

DESIGN: A randomized, controlled 12-week trial. SETTING: Atherosclerosis prevention referral center.

METHODS: Random, nonblinded assignment of participants referred for weight management. The study group (LC) (n = 16) was instructed to consume <20 g of carbohydrate per day for 2 weeks, then <40 g/day for 10 weeks, and to eat LC foods according to hunger. The control group (LF) (n = 14) was instructed to consume <30% of energy from fat. Diet composition and weight were monitored and recorded every 2 weeks. Serum lipid profiles were obtained at the start of the study and after 12 weeks.

RESULTS: The LC group lost more weight (mean, 9.9 +/- 9.3 kg vs 4.1 +/- 4.9 kg, P <.05) and had improvement in non-HDL cholesterol levels (P <.05). There was improvement in LDL cholesterol levels (P <.05) in the LF group but not in the LC group. There were no adverse effects on the lipid profiles of participants in either group.

CONCLUSIONS: The LC diet appears to be an effective method for short-term weight loss in overweight adolescents and does not harm the lipid profile.

PMID: 12640371 [PubMed - in process]

Insulin Response to some energy bars is out of balance

"Compared to white bread, eating the low-carbohydrate bar lowered insulin by about a quarter. Insulin levels rose by more than a third after participants ate the moderate-carbohydrate energy bar, and increased nearly three-quarters after eating the high-carbohydrate energy bar. Eating chicken caused the lowest insulin response – resulting insulin levels were more than three-quarters lower than those caused by white bread."

Full article: Ohio State University

Very-low-carbohydrate weight-loss diets revisted

ABSTRACT
Much scientific and anecdotal data demonstrate favorable metabolic responses to very-low-carbohydrate diets. We believe that very-low-carbohydrate diets merit further study for weight loss, and that criticisms of these diets lack scientific evidence.

KEY POINTS
Most studies have found that people lose more weight on very-low-carbohydrate diets than on standard weight-loss diets.

Mechanisms of weight loss on these diets may go beyond water loss and include suppression of appetite, increasing the metabolic rate, decreasing metabolic efficiency, and shunting of nutrients away from fat storage.

Weight loss is usually associated with small to moderate reductions in lean tissue, but low-energy, very-low-carbohydrate diets may have a protein-sparing effect compared with low-fat diets.

These diets may also have favorable effects on specific risk factors for cardiovascular disease (eg, fasting and postprandial triglyceride levels, high-density lipoprotein levels, and low-density lipoprotein particle size).

Full article: Cleveland Clinical Journal of Medicine, Volume 69, Number 11, November 2002 [PDF File]

High glycemic index foods, overeating, and obesity

Pediatrics 1999 Mar;103(3):E26 Related Articles, Books, LinkOut

High glycemic index foods, overeating, and obesity.

Ludwig DS, Majzoub JA, Al-Zahrani A, Dallal GE, Blanco I, Roberts SB.

Division of Endocrinology, Department of Medicine, Children's Hospital,Boston,
300 Longwood Ave, Boston, MA 02115, USA.

OBJECTIVE: The prevalence of obesity has increased dramatically in recent
years. However, the role of dietary composition in body weight regulation
remains unclear. The purpose of this work was to investigate the acute effects
of dietary glycemic index (GI) on energy metabolism and voluntary food intake
in obese subjects.

METHODS: Twelve obese teenage boys were evaluated on three
separate occasions using a crossover study protocol. During each evaluation,
subjects consumed identical test meals at breakfast and lunch that had a low,
medium, or high GI. The high- and medium-GI meals were designed to have similar macronutrient composition, fiber content, and palatability, and all meals for each subject had equal energy content. After breakfast, plasma and serum
concentrations of metabolic fuels and hormones were measured. Ad libitum food
intake was determined in the 5-hour period after lunch.

RESULTS: Voluntary energy intake after the high-GI meal (5.8 megajoule [mJ]) was 53% greater than after the medium-GI meal (3.8 mJ), and 81% greater than after the low-GI meal (3.2 mJ). In addition, compared with the low-GI meal, the high-GI meal resulted in higher serum insulin levels, lower plasma glucagon levels, lower postabsorptive plasma glucose and serum fatty acids levels, and elevation inplasma epinephrine. The area under the glycemic response curve for each test meal accounted for 53% of the variance in food intake within subjects.

CONCLUSIONS: The rapid absorption of glucose after consumption of high-GI meals induces a sequence of hormonal and metabolic changes that promote excessive food intake in obese subjects. Additional studies are needed to examine the relationship between dietary GI and long-term body weight regulation.

Publication Types:
Clinical Trial
Controlled Clinical Trial
PMID: 10049982 [PubMed - indexed for MEDLINE]