Tag Archives: low-fat diet

Low-Carb Beats Low-Fat Diet for Weight Loss Once Again

…according to an article at MedPageToday.

Many physicians have been reluctant to recommend low-carb diets out of fear that they increase cardiovascular risk. A recent study compared low-carb to low-fat dieting over 12 months and actually found better improvements in cardiovascular disease risk factors on the low-carb diet (max of 40 grams a day).

This Avocado Chicken soup is low-carb. Use the search box to find the recipe.

This Avocado Chicken soup is low-carb. Use the search box to find the recipe.

After 12 months, folks on a low-carbohydrate diet had lost 5.3 kg (11.7 lb), while those on a low-fat diet with similar caloric value had lost 1.8 kg (3.9 lb). Both groups showed lowering of LDL cholesterol, while the low-carbers had better improvements in HDL cholesterol and triglycerides.

DietDoctor Andreas Eenfeldt can add this study to his list of others that show better weight loss with low-carb diets compared to low-fat.

Regular readers here know of my Low-Carb Mediterranean Diet for diabetes and prediabetes. My Advanced Mediterranean Diet for non-diabetics also offers a low-carb option in addition to traditional reduced-calorie portion-control eating.

Steve Parker, M.D.

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David and Goliath: Dr. Briffa Versus National Health Service on Low-Carb Diets

The United Kingdom’s National Health Service last year published guidelines favoring low-fat weight-loss diets over low-carb ones. Dr. John Briffa objects:

See here for a comprehensive review of 23 studies which demonstrates superior results achieved by low-carb diets with regard to weight loss and disease markers. To my mind, dietician Sian Porter and the NHS Choices website have done a bad job of communicating the facts and summarising the evidence. I wish to formally complain about the inaccuracies in this article and its (to me) clear bias and lack of balance.

Read the whole enchilada (plus this update).

Steve Parker, M.D.

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One More Study Shows Low-Carb Beats Low-Fat Diet for Weight Loss

low-carb diet, low-carb fruits, Steve Parker MD

Low-carb isn’t meat-only: You can eat these low-carb fruits

A low-carb diet was superior to a traditional low-fat weight loss diet, and without adverse effects on markers of systemic inflammation, according to a report at ScienceDaily. Some medical professionals are still hesitant to accept the validity of low-carb dieting, fearing that relatively high fat and protein content may promote inflammation, leading to atherosclerosis.  The study at hand should be reassuring in that regard.

Some quotes from ScienceDaily:

The researchers measured the participants’ blood levels for three common markers of inflammation — C-reactive protein, interleukin 6 and tumor necrosis factor-alpha — at the beginning and end of the study. They also measured body weight, body mass index (BMI) and total body and belly fat. At the start, both groups were similar in the various measures, including elevated levels of inflammation markers.

The participants on the low-carb diet lost more weight, on average, than those on the low-fat diet — 28 pounds versus 18 pounds [over the six month trial.

“In both groups, there was a significant drop in the levels of all three measures of inflammation,” says [Kerry] Stewart, indicating that a diet higher in fat and protein doesn’t interfere with the ability to lower inflammation, as long as you are losing weight.

Despite reading several online articles on this study, I can’t determine which low-carb diet was used, nor the level of carbohydrate restriction. Both diet groups exercised three times a week. I expect full details to be published in a scientific journal within a couple years. The research was done at Johns Hopkins University and was not funded by Atkins Nutritionals. U.S. taxpayers funded it.

If you’re looking for a low-carb diet, consider the Low-Carb Mediterranean Diet. Carb restriction starts at under 30 grams a day, but allows for increases over time as long as you’re making weight-loss progress. The typical American eats 250 to 300 grams of carbohydrate daily.

Read the rest at ScienceDaily.

Steve Parker, M.D.

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Mediterranean and Low-Carb Diets Beat Low-Fat for Weight Loss Over Six Years

Israeli flag

Remember Shai et al’s 2008 DIRECT study that compared weight loss over two years on either a low-carb, low-fat, or Mediterranean diet?  I reviewed it at length in 2008.

The same Isreali researchers now report the results of an additional four years of follow-up.  Do you know of any other weight loss study over that length of time?  I don’t.

Of the 322 original study participants, 259 were available for follow-up for an additional four years.  Of these, 67% told researchers they had continued their originally assigned diet.

Over six years, the weight loss was as follows:

  • 0.6 kg (about a pound) in the low-fat group
  • 1.7 kg (almost 4 pounds) in the low-carb cohort
  • 3.1 kg (almost 7 pounds) in the Mediterranean group

The difference between the low-carb and Mediterranean groups was not statistically significant.

Almost all the original study participants (86%) were men, so it’s debatable whether these results apply to women.  I bet they do.  I assume most of the participants were Israeli, so you can also debate whether results apply to other nationalities or ethnicities.

Bottom Line

For long-term weight management, Mediterranean and low-carb diets appear to be more effective than traditional low-fat, calorie-restricted dieting.

Beth Mazur at her Weight Maven blog has some worthwhile comments about the study.

Incidentally, my Advanced Mediterranean Diet (2nd Edition) book features both a traditional Mediterranean diet and the world’s first low-carb Mediterranean diet.

Steve Parker, M.D.

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Is a Low-Carb Diet Safe For Obese Adolescents?

High-protein, low-carbohydrate diets are safe and effective for severely obese adolescent, according to University of Colorado researchers.

Childhood obesity in the U.S. tripled from the early 1980s to 2000, ending with a 17% obesity rate.  Overweight and obesity together describe 32% of U.S. children.  Some experts believe this generation of kids will be the first in U.S. history to suffer a decline in life expectancy, related to obesity.

Colorado researchers wondered if a low-carb, high-protein diet is a reasonable treatment option.  Why high protein?  It’s an effort to preserve lean body mass (e.g., muscle). 

ResearchBlogging.orgThey randomized 46 adoloscents (age 12–18) to either a high-protein, low-carb diet (HPLC diet) or a calorie-restricted low-fat diet to be followed for 13 weeks.  HPLC dieters could eat unlimited calories as long as they attempted to keep carb consumption to 20 g/day or less.  Low-fat dieters were to choose lean protein sources, aiming daily for 2 to 2.5 grams of protein per kilogram of ideal body weight.  Study participants underwent blood analysis and body compositon analysis by dual x-ray absorptiometry.  These kids weighed an average of 108 kg (238 lb) and average body mass index was 39. 

Analysis of food diaries showed the following:

  • Average caloric intake was 1300-1450/day, toward the lower end for the HPLC dieters
  • Energy composition of the HPLC diet: 32% from protien, 11% from carb, 57% from fat
  • Energy compositon of the LF diet: 21% from protein, 51% from carb, 29% from fat
  • Average daily carb consumption for the HPLCers ended up closer to 40 g (still very low) 

Findings

Both groups lost weight, with the HPLC dieters trending to greater weight loss, but not to a statistically significant degree.  They did, however, show a greater drop in body mass index Z-score, however.  Study authors didn’t bother to explain “body mass index Z-scores,” assuming I would know what that meant.  Average weight in the HPLC group dropped 13 kg (29 lb) compared to 7 kg (15 lb) in the low-fat group.

Total and LDL cholesterol fell in both groups, and insulin resistance improved.  Neither diet had much effect on HDL cholesterol.

As usual, triglycerides fell dramatically in the HPLC dieters.

Nearly 40% of the kids—about the same number in both groups—dropped out before finishing the 13 weeks.

The HPLC group did not see any particular preservation of lean body mass, and actually seemed to lose a bit more than the low-fat group.

There were no serious adverse effects in either group. 

Surprisingly, satiety and hunger scores were the same in both groups.  [Low-carb, ketogenic diets have a reputation for satiation and hunger suppression.]

My Comments

This is a small short-term study with a large drop-out rate; we must consider it a pilot study.  That’s why I’m not as enthusiastic about it as the researchers.  Nevertheless, it does indeed suggest that high-protein, low-carb diets are indeed safe and effective in obese adolescents.  It’s a start.   

Steve Parker, M.D.

Reference: Krebs, N., Gao, D., Gralla, J., Collins, J., & Johnson, S. (2010). Efficacy and Safety of a High Protein, Low Carbohydrate Diet for Weight Loss in Severely Obese Adolescents The Journal of Pediatrics, 157 (2), 252-258 DOI: 10.1016/j.jpeds.2010.02.010

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Low-Fat and Low-Carb Diets End Battle in Tie After Two Years, But…

Dieters on low-fat and low-carb diets both lost the same amount of weight after two years, according to a just-published article in Annals of Internal Medicine.  Both groups received intensive behavioral treatment, which may be the key to success for many.  Low-carb eating was clearly superior in terms of increased HDL cholesterol, which may help prevent heart disease and stroke.

The study was funded by the National Institutes of Health and was carried out in Denver, St. Louis, and Philadelphia.

How Was It Done?

Healthy adults aged 18-65 were randomly assigned to either a low-fat or low-carbohydrate diet.  Average age was 45.  Average body mass index was 36 (over 25 is overweight; over 30 is obese).  Of the 307 participants, two thirds were women.  People over 136 kg (299 lb) were excluded from the study—I guess because weight-loss through dieting is rarely successful at higher weights.  Diabetics were excluded. 

The low-carb diet:  Essentially the Atkins diet with a prolonged induction phase (12 weeks instead of two).  Started with maximum of 20 g carbs daily, as low-carb vegetables.  Increase carbs by 5 g per week thereafter as long as weight loss progressed as planned.  Fat and protein consumption were unlimited.  The primary behavioral goal was to limit carb consumption.

The low-fat diet:  Calories were limited to 1200-1500 /day (women) or 1500-1800 (men).  [Those levels in general are too low, in my opinion.]  Diet was to consist of about 55% of calories from carbs, 30% from fat, 15% from protein.  The primary behavioral goal was to limit overall energy (calorie) intake. 

Both groups received frequent, intensive in-person group therapy—lead by dietitians and psychologists—periodically over two years, covering such topics as self-monitoring, weight-loss tips, management of weight regain and noncompliance with assigned diet.  Regular walking was recommended.

Body composition was measured periodically with dual X-ray absorptiometry.

What Did They Find?

Both groups lost about 11% of initial body weight, but tended to regain so that after two years, both groups average losses were only 7% of initial weight.  Weight loss looked a little better at three months in the low-carb group, but it wasn’t statistically significant. 

The groups had no differences in bone density or body composition.

No serious cardiovascular illnesses were reported by participants.  During the first six months, the low-carb group reported more bad breath, hair loss, dry mouth, and constipation.  After six months, constipation in the low-carb group was the only symptom difference between the groups.

During the first six months, the low-fat group had greater decreases in LDL cholesterol (with potentially less risk of heart disease), but the difference did not persist for one or two years.

Increases in HDL cholesterol (potentially heart-healthy) persisted throughout the study for the low-carb group.  The increase was 20% above baseline.

About a third of participants in both groups dropped out of the study before the two years were up.  [Not unusual.]

My Comments

Contrary to several previous studies that suggested low-carb diets are more successful than low-fat, the study at hand indicates they are equivalent as long as dieters get intensive long-term group behavioral intervention. 

Low-carb critics warn that the diet will cause osteoporosis, a dangerous thinning of the bones that predisposes to fractures.  This study disproves that.

Contrary to widespread criticism that low-carb eating—with lots of fat and cholestrol— is bad for your heart, this study notes a sustained elevation in HDL cholesterol (“good cholesterol”) on the low-carb diet over two years.  This also suggests the low-carbers  followed the diet fairly well.  The investigators also note that low-carb eating tends to produce light, fluffy LDL cholesterol, which is felt to be less injurious to arteries compared to small, dense LDL cholesterol.

A major strength of the study is that it lasted two years, which is rare for weight-loss diet research.

A major weakness is that the investigators apparently didn’t do anything to document the participants’ degree of compliance with the assigned diet.  It’s well known that many people in this setting can follow a diet pretty well for two to four months.  After that, adherence typically drops off as people go back to their old habits.  The group therapy sessions probably improved compliance, but we don’t know since it wasn’t documented. 

How often do we hear “Diets don’t work.”  Well, that’s just wrong.

Overall, it’s an impressive study, and done well. 

Individuals wishing to lose weight on their own can’t replicate these study conditions because of the in-person behavioral intervention component.  There are lots of self-help calorie-restricted balanced diets (e.g., Sonoma Diet, The Zone,  Advanced Mediterranean Diet) and low-carb diets (e.g., Atkins Diet, Banting’s Letter on Corpulence, Low-Carb Mediterranean or Ketogenic Mediterranean Diets).  On-line support groups—e.g. Low Carb Friends and SparkPeople and 3 Fat Chicks on a Diet—could supply some necessary behavioral intervention strategies and support.  

Choosing a weight-loss program is not as easy as many think.  [Well, I’ll admit that choosing the wrong one is easy.]  I review the pertinent issues in my “Prepare for Weight Loss” page.

Steve Parker, M.D.

Reference: Foster, Gary, et al.  Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial. Annals of Internal Medicine, 153 (2010): 147-157   PMID: 20679559

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Atkins Diet Beats Low-Fat Diet Over Three Months in Overweight Diabetic Black Women

MPj04384250000[1]A recent study compared effects of a low-carb versus low-fat diet in overweight diabetics (mostly blacks).  After one year, the only major difference they found was  lower HDL cholesterol in the low-carb eaters.  The low-carb diet was more effective measured at three months into the study.  Study participants were overwhelmingly black women, so the findings may not apply to you.

Background

The authors note at the outset that:

Optimal weight loss strategies in patients with type 2 diabetes continue to be debated, and the best dietary strategy to achieve both weight loss and glycemic control . . . is unclear.

They also note that in short-term randomized studies, low-carb diets help improve glucose control in type 2 diabetics.

Methodology

Participants (105) were randomized to either:

  • a low-fat diet in the fashion of the Diabetes Prevention Program, with a fat gram goal of 25% of energy needs, or . . .
  • the Atkins diet, including the 2-week induction phase and gradually increasing carb grams weekly, etc.

The adult partipants were black (64%), Hispanic (16%), white (15%), or other.  Women were 80% of the group.  Average age 54.  Average weight 215 pounds (98 kg).  Average BMI 36.  Most of them were taking metformin, half were taking a sulfonylurea, 30% were on insulin.  Thiazolidinedione drugs were discontinued since they cause weight gain as a side effect.  Short-acting insulins were changed to glargine (Lantus) to help avoid hypoglycemia.  For the low-carb group initially, insulin dosages  were reduce by half and sulfonylureas were stopped (again, to minimize hypoglycemia).  For the low-fat group, insulin was reduced by 25% and sulfonylurea by 50%.  Metformin was not adjusted.  Subjects were instructed to keep daily food diaries.  Goal rate of weight loss was one pound per week.   

Results

The drop-out rate by the end of 12 months was the same in both groups – 20%.  The low-carbers lost weight faster (3.7 lb/month) in the first three months, but by month twelve each group had the same 3.4% reduction of weight (6.8 lb or 3 kg).  As measured at 3 months, low-carbers were down 11.4 lb (5.2 kg) and low-fat dieters were down 7 lb (3.2 kg).  Maximum weight loss was at 3 months, then they started gaining it back.  At 12 months, low-carb subjects using insulin were on 10 less units, while low-fat dieters were using 4 more units (not statistically significant).  Hemoglobin A1c measured at 3 months was down 0.64 in the low-carb group and down0.26 in the low-fat.  By 12 months, HgbA1c’s were back up to baseline levels for both groups.  Blood lipids were the same for both groups at 12 months except HDL was about 12% higher in the low-carb dieters.

At baseline, subjects derived 43% of calories from carbohydrates, 36% from fats, 23% from proteins.  At three months, the low-carb group ate 24% of calories as carbohydrates (estimated at 77 grams of carb daily) and 49% from fat.  The low-fat group at 3 months derived 53% of calories from carbohydrate (199 grams/day) and 25% from fat. Diet compliance deteriorated as time passed thereafter. 

Study Author Conclusions

After one year, the low-carb and low-fat groups had similar weight reductions.  The low-carb dieters raised their HDL cholesterol levels significantly [which may protect against heart disease].

My Comments

Lasting weight loss is difficult!  Down only 6.8 pounds for a year of  effort. 

These study participants needed to lose a lot more than 6.8 pounds.  They needed to lose 50.  Both groups were woefully noncompliant with diet recommendations by the end of the study year.  They were eating more carbs or other calories than they were assigned.  But their results weren’t much different than other groups studied for an entire year. 

How do we keep people fired up about maintaining their weight-loss efforts?  The solution to that problem will win someone a Nobel Prize.

The Atkins diet was superior – for weight loss and glycemic control – when measured at three months, when compliance by both groups was still probably fairly good.

Results of this study may apply only to black women.  There weren’t enough men and other ethnic groups to make meaningful comparisons.    

Steve Parker, M.D.        

Reference:  Davis, Nichola, et al.  Comparative study of the effects of a 1-year dietary intervention of a low-carbohydrate diet versus a low-fat diet on weight and glycemic control in type 2 diabetes.  Diabetes Care, 32 (2009): 1,147-1,152.

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