Category Archives: Fat in Diet

Are Refined Carbs Worse for Your Heart Than Saturated Fat?

To reduce coronary heart disease, we need to focus on reducing consumption of refined carbohydrates rather than fat and cholesterol, according to Dr. Frank Hu.

Dr. Hu is not a wild-eyed, bomb-throwing radical. He’s a Harvard professor of nutrition and epidemiology with both M.D. and Ph.D. degrees.  High-glycemic-index carbs in particular are the bad boys, he writes in an editorial published in the American Journal of Clinical Nutrition earlier this year.

Additional details are at my April 26, 2010, post at the Self/NutritionData Heart Health Blog.

Steve Parker, M.D.

2 Comments

Filed under Carbohydrate, coronary heart disease, Fat in Diet, Glycemic Index and Load

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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Filed under Carbohydrate, Fat in Diet, ketogenic diet, Protein, Weight Loss

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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Filed under Carbohydrate, Fat in Diet, ketogenic diet, Overweight and Obesity, Weight Loss

Maybe Diet Prevents Alzheimer Dementia After All

I blogged about a study by Gu et al on April 30, 2010, that found significantly lower incidence of Alzheimer dementia in people in Manhattan who followed this dietary pattern:

  • relatively high consumption of salad dressing, nuts, fish, tomatoes, fruits, dark green leafy vegetables, and cruciferous  vegetables
  • relatively low consumption of poultry, red meat, butter, and high-fat dairy

About the same time, a National Institutes of Health expert panel pooh-poohed the possibility that diet had any effect one way or the other on Alzheimer’s

Why does this matter?  Five million U.S. adults have Alzheimer dementia already, and it’s going to get much worse over the coming decades.

A June, 2010, issue of Journal of the American Medical Association has a commentary by two doctors (Martha Morris, Sc.D., and Christine Tangney, Ph.D.), experts in the field of nutrition.  Here’s their explanation of the NIH panel’s negative findings:

Many of the inconsistencies among studies of dietary factors can be attributed to the complexity of nutrition science and the omission of nutrition expertise in the design and analysis of both epidemiological and randomized controlled trials.

Morris and Tangney think the findings of Gu et al are valid, confirming prior studies showing benefit to diets high in vitamin E (from food) and low in saturated fat from animals.  They point out that the animal foods may simply be displacing beneficial nutrients in other foods, rather than directly causing harm.

Until we have further data, anyone at risk for Alzhiemer’s may be better off following the dietary pattern above, or the Mediterranean diet.  The two are similar.

Steve Parker, M.D.

Disclaimer:  All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status.  Always consult your personal physican before making any dietary or exercise changes. 

Reference: Morris, M., & Tangney, C.  Diet and Prevention of Alzheimer Disease.  The Journal of the American Medical Association, 303 (2010): 2,519-2,520.    doi: 10.1001/jama.2010.844

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Filed under Dairy Products, Fat in Diet, Fish, Fruits, Health Benefits, Mediterranean Diet, nuts, Vegetables

Basic Science: Mediterranean Diet Boosts Antioxidant Power

Compared to the low-fat American Heart Association diet, the traditional Mediterranean diet rich in olive oil has more capacity to counteract potentially harmful “free radicals” and “reactive oxygen species” in our bodies, according to researchers at the University of Navarra in Spain.

Our tissues normally contain free radicals and reactive oxygen species, which are intrinsic to cell metabolism.  They serve useful purposes.  In excessive amounts, however, many believe they cause “oxidative damage” and thereby contribute to chronic degenerative conditions such as atherosclerosis, aging, dementia, and cancer.

Antioxidants are thought to neutralize free radicals and reactive oxygen species, which may lead to better health.

The PREDIMED study is an ongoing Spanish project testing the heart-protective effects of the Mediterranean diet in high-risk people over the course of four years.  The three intervention groups are 1) Medi diet plus supplemental virgin olive oil, 2) Medi diet plus extra tree nuts, and 3) low-fat American Heart Association diet.

After three years of follow-up, the researchers measured “total antioxidant capacity” in the bloodstream of a subset of the PREDIMED participants.

They found that the two Mediterranean diet groups had significantly greater total antioxidant capacity, about 50% more than the low-fat control group.  Within the Medi + olive oil group, the participants with the highest levels of antioxidant capacity actually tended to lose weight, an association not seen in the other groups.

The Researchers’ Conclusions

Mediterranean diet, especially rich in virgin olive oil, is associatied with higher levels of plasma antioxidant capactiy.  Plasma total antioxidant capacity is related to a reduction in body weight after three years of intervention in a high cardiovascular risk population with a Mediterranean-style diet rich in virgin olive oil.

In other words, the Mediterranean diet with virgin olive oil may help you keep your weight under control, and the antioxidant capacity may contribute to the well-documented health benefits of the diet.

Steve Parker, M.D.

PS:  It’s impossible to tell from this report just how much weight loss was seen in the high-TAC Medi+olive oil subjects.  I doubt it was much.  Baseline body mass index for all participants was around 29, so they were overweight and just a shade under obese.

PPS:  Both the Ketogenic Mediterranean and Diabetic Mediterranean Diets mandate minimal amounts of olive oil consumption, with no upper limit.

Reference: Razquin, C., et al. A 3 year follow-up of a Mediterranean diet rich in virgin olive oil is associated with high plasma antioxidant capacity and reduced body weight gain.  European Journal of Clinical Nutrition, 63 (2009): 1,387-1,393.  doi 10.1038/ejcn.2009.106

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Filed under Fat in Diet, Health Benefits, Mediterranean Diet, Weight Loss

Seminal Paper: Carbohydrate Restriction for Type 2 Diabetes and Metabolic Syndrome

Carbohydrate-restricted eating is slowly gaining mainstream acceptance as treatment for type 2 diabetes and metabolic syndrome.  I thought it would be useful to present one of the watershed reports that summarize the potential benefits.  The article is from 2008.  Among the co-authors are some of the brightest names in this field: Richard K. Bernstein, Annika Dahlqvist, Richard Feinman, Eugene J. Fine, Robert Lustig, Uffe Ravnskov, Jeff Volek, Eric Westman, and Mary C. Vernon.

ResearchBlogging.orgThese are not wild-eyed, bomb-throwing radicals.  They are on faculty at some of the best institutes of higher learning.  They note that while many of the national diabetes organizations downplay the benefits of carb restriction, we have enough evidence now to warrant careful reconsideration.

Here are some of their major points, all backed up by references (68) from the scientific literature:

  1. Glucose (blood sugar) is a “major control element,” whether directly or indirectly through insulin, in glycogen metabolism, production of new glucose molecules, and in formation and breakdown of fat.
  2. The potential adverse effects of dietary fat are typically seen with diets high in carbohydrate.
  3.  Carb restriction improves control of blood sugars, a major target of diet therapy.  Many of the supportive studies were done with overweight or obese people (85% of type 2 diabetics are overweight).  Very low-carb diets are often so effective that diabetic medications have to be reduced at the outset of the diet. 
  4. For weight loss, carb-restricted diets work at least as well as low-fat diets.  They are usually superior. 
  5. Carb-restricted diets usually replace carbs with fat, resulting in improve markers for cardiovascular disease (lower serum triglycerides and higher HDL cholesterol levels). Replacing dietary fat with carbohydrate—the goal of many expert nutrition panels over the last 40 years—tends to increase the amount of artery-damaging “small, dense LDL cholesterol” in most of the population. 
  6. Carbohydrate restriction improves all five components of the metabolic syndrome: obesity, low HDL cholesterol, high triglycerides, high blood pressure, elevated blood sugar.
  7. Beneficial effects of carbohydrate restriction seem to occur even without weight loss
  8. Still worried about excessive fat consumption?  Many low-carb dieters demonstrate a significant increase in the percentage of total calories from fat, but without an increase in the absolute amount of fat eaten.  That’s because they simply reduced their total calories by reducing carb consumption. 

This post was chosen as an Editor's Selection for ResearchBlogging.orgThe authors in 2008 called for a widespread reappraisal of carbohydrate restriction for type 2 diabetes and metabolic syndrome.  It’s been happening, and many patients are reaping the benefits.

Steve Parker, M.D.

Reference: Accurso A, Bernstein RK, Dahlqvist A, Draznin B, Feinman RD, Fine EJ, Gleed A, Jacobs DB, Larson G, Lustig RH, Manninen AH, McFarlane SI, Morrison K, Nielsen JV, Ravnskov U, Roth KS, Silvestre R, Sowers JR, Sundberg R, Volek JS, Westman EC, Wood RJ, Wortman J, & Vernon MC (2008). Dietary carbohydrate restriction in type 2 diabetes mellitus and metabolic syndrome: time for a critical appraisal. Nutrition & metabolism, 5 PMID: 18397522

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Filed under Carbohydrate, Fat in Diet

Low-Carb Mediterranean Diet Improves Glucose Control and Heart Risk Factors in Overweight Diabetics

In overweight type 2 diabetics, a low-carbohydrate Mediterranean diet improved HDL cholesterol levels and glucose control better than either the standard Mediterranean diet or American Diabetes Association diet, according to Israeli researchers reporting earlier this year.

Background

Prior studies suggest that diets rich in monounsaturated fatty acids (olive oil, for example) elevate HDL cholesterol and reduce LDL cholestrol and triglycerides in type 2 diabetics.

Low-carb diets improve blood sugar levels and reduce excess body weight in type 2 diabetics, leading to the ADA’s allowance in 2008 of a low-carbohydrate diet as an alternative to standard diabetic diets.

Many—probably most—type 2 diabetics have insulin resistance:  the body’s cells that can remove sugar from the bloodstream are not very sensitive to the effect of insulin driving sugar into those cells.  They “resist” insulin’s effect.  Consumption of monounsaturated fatty acids  improves insulin sensitivity.  In other words, insulin is better able to push blood sugar into cells, removing it from the bloodstream.

Previous studies have shown that both low-carb diets and the Mediterranean diet reduce after-meal elevations in blood sugar, which likely lowers levels of triglycerides and LDL cholesterol.

How Was the Study Done?

The goal was to compare effects of three diets in overweight type 2 diabetics in Israel over the course of one year.  Study participants totalled 259.  Average age was 56, average weight 86 kg (189 lb), average hemoglobin A1c 8.3%, and average fasting plasma glucose (sugar) was 10.3 mmol/L (185 mg/dl).  [Many diabetics in the U.S. fit this profile.]  People taking insulin were excluded from the study, as were those with proliferative diabetic retinopathy—no reasons given. 

Participants were randomly assigned to one of three diets, so there were about 85 in each group.  [Over the course of one year, people dropped out of the study for various reasons, leaving each group with about 60 subjects.] 

Here are the diets:

  • 2003 ADA (American Diabetes Association) diet:  50-55% of total caloric intake from carbohydrate (mixed glycemic index carbs), 30%  from fat, 20% from protein
  • Traditional Mediterranean (TM):  50-55% low-glycemic-index carbs, 30% fat—high in monounsaturated fat, 15-20% protein
  • Low-carb Mediterranean (LCM) :  35% low-glycemic-index carbs, 45% fat—high in monounsaturated fat, 15-20% protein

Patients were followed-up by the same dietitian every two weeks for one year.  All were advised to do aerobic exercise for 30-45 minutes at least three days a week.

Olive oil is traditionally the predominant form of fat in the Mediterranean diet and is a particularly rich source of monounsaturated fat.  At no point in this report was olive oil mentioned, nor any other source of monounsaturated fat.  Until I hear otherwise, I will assume that olive oil was the major source of monounsaturated fat in the TM and LCM diets. 

 All diets were designed to provide 20 calories per kilogram of body weight. 

In all three diets, saturated fat provided 7% of total calories.  Monounsaturated fatty acids provided 23% of total calories in the LCM, and  10% in the other two diets.  Polyunsaturated fatty acids provided 15% of calories in the LCM, and 12% in the other two diets.  The ADA diet provided 15 grams of fiber, the TM had 30 g, and the LCM had 45 g.

Adherence to the assigned diet was assessed with a “food frequency questionnaire” administered at six months.

What Did the Researchers Find?

Average reported energy intake was similar in all three groups: 2,222 calories per day.

Monounsaturated fat intake differences were statistically significant: 14.6, 12.8, and 12.6% for the LCM, TM, and ADA diets, respectively.  Polyunsaturated fat intake differences were statistically significant: 12.9, 11.5, and 11.2% for the LCM, TM, and ADA diets, respectively.

Percentage of energy from carbs was highest for the ADA diet (45.4%), intermediate for the TM diet (45.2%), and lowest for the LCM diet (41.9%).

At the end of 12 months, all three groups lost about the same amount of weight (8-9 kg or 18-20 lb), body mass index, and waist circumference.

Hemoglobin A1c fell in all three groups, but was significantly greater for the LCM group than for the ADA diet (6.3% absolute value vs 6.7%).

Triglycerides fell in all three groups, but was significantly greater for the LCM diet compared to the ADA diet.

The LCM group achieved a significant increase (12%) in HDL cholesterol compared to the ADA diet, but not different from the TM group.

LDL cholesterol fell in all three groups, and the LCM group’s drop (25%) was clearly superior to that of the ADA diet (14%) but about the same as the TM diet (21%).

Conclusions of the Investigators

We found that an intensive community-based dietary intervention reduced cardiovascular risk factors in overweight patients with [type 2 diabetes] for all three diets.  The LCM group had improved cardiovascular risk factors compared to either the ADA or the TM groups.

Only the LCM improved HDL levels and was superior to both the ADA and TM in improving glycaemic control.

It would appear that the low carbohydrate Mediterranean diet should be recommended for overweight diabetic patients.

My Comments

There’s no way the average diabetic could replicate this low-carb Mediterranean diet without working closely with a dietitian or nutritionist.

Any superiority of this low-carb Mediterranean diet may have as much to do with the increased monounsaturated fat intake as with the reduced carb consumption.  Monounsaturated fatty acid consumption is thought to improve insulin sensitivity. 

NutritionData’s Nutrient Search Tool can give you a list of foods high in monounsaturated fat.

The Mediterranean diet and low-carb diets independently have been shown to lower after-meal glucose levels, which probably lowers LDL cholesterol and triglycerides.

I’m disappointed the dietitians were not able to achieve a lower level of carbohydrate consumption in the low-carb Mediterranean diet group.  I suspect if they had, improvements in glucose control and lipids would have been even better.  But proof awaits another day.

We saw last year an article in the Annals of Internal Medicine that showed a dramatic reduction in the need for glucose-lowering drugs in type 2 diabetics following a different low-carb Mediterranean diet over four years, compared to a low-fat American Heart Association diet.  These two studies convince me a low-carb Mediterranean diet has real life-preserving and life-enhancing potential. 

Diabetics looking for a low-carb Mediterranean diet today have several options:

If you’re aware of any other low-carb, explicitly Mediterranean-style diets, please share in the Comments section.

Steve Parker, M.D. 

References: 

Elhayany, A., Lustman, A., Abel, R., Attal-Singer, J., and Vinker, S.  A low carbohydrate Mediterranean diet improves cardiovascular risk factors and diabetes control among overweight patients with type 2 dabetes mellitus:  a 1-year prospective randomized intervention studyDiabetes, Obesity and Metabolism, 12 (2010): 204-209.

Esposito, Katherine, et al.  Effects of a Mediterranean-style diet on the need for antihyperglycemic drug therapy in patients with newly diagnosed type 2 diabetesAnnals of Internal Medicine, 151 (2009): 306-314.

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Filed under Carbohydrate, coronary heart disease, Fat in Diet, Glycemic Index and Load, Mediterranean Diet, olive oil

Individual Response to Weight-Loss Diet May Depend on Genes

Dieters with particular genetic make-up respond better or worse to specific types of weight-loss diets, suggest researchers who presented data at the 2010 Cardiovascular Disease Epidemiology and Prevention /Nutrition, Physical Activity, and Metabolism conference.  Findings are preliminary, but may explain the common phenomenon of two people going on the same diet, but only one achieving good results. 

I’ll bet you can imagine several other explanations.

Several years ago, the “A to Z” study compared the weight loss of 311 overweight women on one of four diets:  Atkins (low-carb), Ornish (very low fat, vegetarian), Learn (low-fat), and Zone (moderate carb restriction, high protein, moderate fat).  Atkins was a bit better than the other diets, in terms of long-term (one year) weight loss.  But within each diet group, some women lost 40–50 pounds (18–23 kg), whereas others gained over 10 pounds (4.5 kg).

Stanford University researchers obtained DNA from 138 of the 311 women and noted the occurence of three genes—ABP2, ADRB2, and PPAR-gamma—that had previously been shown to predict weight loss via diet-gene interactions.  For example, a particular mix of these genes predict better weight loss with a low-fat diet; a different mix predicts more loss with a low-carb diet.

Women who had been randomly assigned to one of the A to Z diets tended to lose much more weight if they happened to have the gene mix appropriate for that diet (compared to those on the same diet with the wrong gene mix).  The difference, for example, might be loss of 12 pounds versus two pounds.

The lead researcher, Dr. Mindy P. Nelson, told TheHeart.Org that the proportion in the general population genetically predisposed to the low-fat versus low-carb approach is about 50:50.

Take-Home Points

These results, again, are preliminary; additional testing is necessary for confirmation.  If they had been able to test the DNA of the other 178 women in the A to Z study, the results could have been either stronger or shown no diet-gene interaction.  The study hasn’t even been published in a peer-reviewed journal yet.

Men may or may not be subject to similar diet-gene interaction.

If a genetic test is ever clinically available to tell a dieter which type of weight-loss diet would be more successful, it will likely be cheaper to just try a particular diet first and see if it works over 4–6 weeks.  Successful long-term weight loss is like smoking cessation—most smokers try 5–7 different times or methods before hitting on one that works for them.

This potential diet-gene interaction could be a major finding that will stop the arguing about which is the single best way to lose excess fat.  Many paths may lead to the mountaintop. 

Steve Parker, M.D.

Reference:  O’Riordan, Michael.  Dieting by DNA?  Popular diets work best by genotype, reseach shows.  HeartWire by TheHeart.Org, March 8, 2010.

6 Comments

Filed under Carbohydrate, Fat in Diet, ketogenic diet, Vegetarian Diet, Weight Loss

Book Review: The New Atkins for a New You

Here’s my review of The New Atkins for  a New You, a weight-loss book by Dr. Eric Westman, Dr. Stephen Phinney, and Dr. Jeff Volek released a week ago.  The copyright holder is Atkins Nutritionals, Inc.  Under Amazon.com’s five-star rating system, I give it four stars (“I like it”).  

♦   ♦   ♦ 

The most exciting nutritional medicine development in recent memory is the fact that saturated fat consumption is not a significant cause of heart disease and premature death. The same goes for for total fat and cholesterol.  When enough physicians, nutritionists, and dietitians learn this, low-carb eating will take off like a rocket.

For those unfamiliar with the Atkins diet, it is designed for weight loss via high fat consumption and major carbohydrate restriction.  Protein intake is a bit higher than average.  As long as carbohydrates (carbs) are kept low, other foods are mostly unlimited.  Atkins has four phases.  As you graduate from one phase tothe next, more carbs are allowed, adding some carb sources before others (the Carb Ladder). 

Atkins has been around for years.  It’s not just a weight-loss diet; it’s a lifetime way of eating.

Doctors Westman, Phinney, and Volek are leaders in low-carb nutritional science.  The last time Atkins peaked (2003), we didn’t have the scientific studies backing up safety of the diet.  Now we do, in large part thanks to these guys. 

Physicians see beaucoup patients with overweight-related medical conditions.  We’re not going to recommend a diet that causes heart attacks, strokes, and other major medical complications.  Published research over the last eight years has established the relative safety of very low-carb diets, particularly Atkins.  Low-carb diets may even be healthier than the low-fat, high-carb diet that has been recommended by U.S. public health authorities for the last forty years.  Come to think of it, our current obesity and diabetes epidemics started around that same time.

The book covers nutrition basics, day-to-day practical application of Atkins eating, recipes and detailed meal plans, and the science behind the program.    

What’s New Since Dr. Atkins’ 2002 Book?

  • adaptations for vegetarians and vegans
  • adaptations for Latinos
  • coffee is now OK
  • introduction of the term “foundation vegetables” and almost doubling the amount of vegetables allowed in Phase 1: “approximately six cups of salad and up to two cups of cooked vegetables, depending upon the ones you select”
  • more flexility, such as the option to skip Phase 1 (induction)
  • focus on adequate protein intake, based on your height
  • emphasis on getting enough omega-3 fatty acids
  • no emphasis on supplements and low-carb products sold by Atkins Nutritionals,Inc.
  • diet journals—a personal record of your weight-loss journey—are recommended
  • eliminate or minimize “induction flu” and constipation (in Phase 1) by eating at least 1/2 teaspoon of salt daily [I’m skeptical.]
  • discussion of the trendy omega-6/omega-3 fatty acid ratio
  • favor monounsaturated fatty acids (e.g., olive oil, canola oil) over certain polyunsaturated fats, as in oils from corn, soybeans, sunflower, cottonseed, and peanuts
  • no mention of testing urine for ketosis
  • more discussion of psychological aspects of weight

The lack of ads for Atkins Nutritionals products is welcome and refreshing.  Too many of the official Atkins books read like infomercials, which diminishes credibility.

A vegetarian or vegan “Atkins diet” is just not something I can visualize.

What Could Have Been Done Better?

  • no specific amounts given for these recommended supplements: calcium, vitamin D, omega-3 fats, multivitamin, magnesium and other minerals (except “no iron”).  [Is the idea to encourage a visit the official Atkins website?]
  • little guidance for physicians who are to advise diabetics doing Atkins.  Few physicians are familiar enough with the program to make the necessary changes in particular diabetic medications.
  • little discussion of the constipation and leg cramps that often accompany very low-carb diets
  • the hype on the cover: “How would you like to LOSE UP TO 15 POUNDS IN TWO WEEKS!”  [To their credit, the authors note that such results are not typical.]
  • nearly all the measurements are U.S. Customary.  Metric users are out of luck.
  • four phases seem a bit much.  The beauty of Atkins Phase 1 is its simplicity. 

My favorite sentence: “White flour is better suited to glue for kindergarten art projects than to nutrition.”

My least favorite sentence: “We can’t stress strongly enough that the best diet for you is one composed of foods you love.”  I love apple pie and Cinnabon cinnamon rolls, but they won’t help me manage my weight.

The only error I found worth mentioning is minor.  The authors state that the American Heart Association recommends consumption of fish three times a week. The official policy is still “at least twice weekly.”

The book is very practical and easily understood by average people.  Most will skip the science chapters at the end.  I know the basic Atkins program works at least short-term; many of my patients have done it.

In summary, the book has nearly everything you need to be successful with the Atkins diet. 

As far as I know, there are no comprehensive long-term studies (e.g., 10+ years) regarding health outcomes of Atkins-style eating.  In other words, does Atkins have any effect on longevity, cancer, heart attacks, strokes, etc.?  But very few of the popular diets have these data either.  The best researched ways of eating in this respect are the Mediterranean diet and vegetarian diets.

Steve Parker, M.D.

Disclosure:  I was given nothing of value for this review by the authors, publisher, or Atkins Nutritionals, Inc.  I wrote it for the benefit of my patients and readers.

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Filed under Book Reviews, Carbohydrate, Fat in Diet, ketogenic diet, Weight Loss

Low-Carb Killing Spree Continues

The choice is clear . . . NOT

Low-fat and low-carb diets produce equal weight loss and improvements in insulin resistance but the low-carb diet may be detrimental to vascular health, according to a new study in Diabetes.

Methodology

Researchers in the the UK studied 24 obese subjects—15 female and 9 male—randomized to eat either a low-fat (20% fat, 60% carbohydrate) or low-carb (20% carb, 60% fat) diet over 8 weeks.  Average age was 39; average body mass index was 33.6.  Most of them had prediabetes.  Food intake was calculated to result in a 500 calorie per day energy deficit (a reasonable reduced-calorie diet, in other words).  Study participants visited a nutritionist every other day, and all food was provided in exact weighed portions. 

Results

Both groups lost the same amount of weight, about 7.3% of initial body weight. 

Triglycerides dropped by a third in the low-carb group; unchanged in the low-fat cohort.  Changes in total cholesterol, LDL cholesterol, and HDL changes were about the same for both groups.

Systolic blood pressure dropped about 10 points in both groups; diastolic fell by 5 in both.

Aortic augmentation index” fell significantly in the low-fat group and tended to rise in the low-carb group.  According to the researchers, the index is used to estimate systemic arterial stiffness.  [In general, flexible arteries are better for you than stiff ones.  “Hardening-of-the-arteries,” etc.]  The low-fat group started with a AAI of 17, the low-carb group started at 12.  They both ended up in the 13-14 range. 

Peripheral insulin sensitivity improved significantly only in the low-carb group but “there was no significant difference between groups.”  No difference between the groups in hepatic (liver) insulin resistance. 

Fasting insulin levels fell about 20% in the low-fat group and about 40% in the low-carb group, a difference not reaching statistical significance (p=0.17).

The Authors’ Conclusions

This study demonstrates comparable effects on insulin resistance of low-fat and low-carbohydrate diets independent of macronutrient content.  The difference in augmentation index may imply a negative effect of low-carbohydrate diets on vascular risk.

My Comments

Yes, you can indeed lose weight over eight weeks on both low-fat and low-carb diets, if you follow them.  So diets DO work.  No surprise.

Loss of excess body fat by either method lowers your blood pressure.  No surprise.

Once again, concerns about low-carb/high-fat diets adversely affecting common blood lipids—increasing heart disease risk—are not supported.  No surprise

Hyperinsulinemia and insulin resistance are risk factors for development of diabetes and cardiovascular disease.  Results here tend to favor the low-carb diet.  I have to wonder if a study with just twice the number of test subjects would have shown a clear superiority for the low-carb diet.

The authors imply that aortic augmentation index is an important measure in terms of future cardiovascular health.  A major conclusion of this study is that a change in this index with the low-carb diet might adveresly affect heart health.  Yet they don’t bother to discuss this test much at all.  I’m no genius, but neither are the typical readers of Diabetes.  I doubt that they are any more familiar with that index than am I, and I’d never heard of it before. 

[Feel free to educate me regarding aortic augmentation index in the comment section.]

Unfortunately, many readers of this journal article and the associated news releases will come away with the impression, once again, that low-carb diets are bad for your heart. 

I’m not convinced.

Steve Parker, M.D.   

References:

Bradley, Una, et al.  Low-fat versus low-carbohydrate weight reduction diets.  Effects on weight loss, insulin resistance, and cardiovascular risk: A randomized control trialDiabetes, 58 (2009): 2,741-2,748.

Nainggolan, Lisa.  Low-carb diets hit the headlines again.  HeartWire, December 11, 2009.

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Filed under Carbohydrate, coronary heart disease, Fat in Diet, Prevention of T2 Diabetes, Weight Loss