Tag Archives: Atkins diet

ADA Now Says Low-Carb Diets OK for Overweight Type 2 Diabetics

CB037166Eighty-five percent of type 2 diabetics are overweight or obese.  Overweight either causes or aggravates many cases of diabetes.

For the last quarter-century, many U.S. government agencies and healthcare organizations have advocated a low-fat diet for overweight people, including type 2 diabetics.  Recent studies have documented that low-carbohydrate diets can also be effective in weight loss.  Low-carb diets replace carbohydrates with either fats or proteins, or both.  The A to Z Weight Loss Study compared the Atkins, Ornish, LEARN, and Zone diets in 311 overweight pre-menopausal women.  The Atkins group tended to lose a bit more weight. Changes in lipid profiles, waist-hip ratios, fasting insulin and glucose levels, blood pressure, and percentage of body fat were comparable or better with Atkins versus the other diets.

The Amerian Diabetes Association now gives the go-ahead for use of low-carb diets as a weight-control method for type 2 diabetics.  Previously, the organization had recommended against diets that restrict carbohydrates to less than 130 grams daily.  (A baked potatoe without the skin has 30 grams.)  Understand that the ADA does not endorse low-carb diets for weight loss or diabetes management.  They simply say that either low-carb or low-fat calorie-restricted diets might be effective for up to one year.

I caution you that low-carb diets may be deficient in fiber, minerals, vitamins, and phytonutrients that may be very beneficial in terms of long-term health and longevity.

The tide has been turning against low-fat diets for the last six years.

Steve Parker, M.D.

Reference: American Diabetes Association.  Clinical Practice Recommendations 2008.  Diabetes Care, 31 (2008): S61-S78.

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Are High-Protein Weight-Loss Diets Safe and Effective?

Animal protein

Animal protein

According to researchers at Tufts University, high-protein weight-loss diets may be effective and safe except for people prone to kidney stones, chronic kidney disease, and people with diabetes.  Long-term effects on bone health – osteoporosis, specifically – might be a problem.

High-protein weight-loss diets have been popular for a while.  “Protein Power” by Drs. Michael and Mary Eades is an example.  The Atkins diet may be, too.  If you increase the protein in your diet, you generally are decreasing carbohydrates or fat, or both, at the same time.   

I found a scientific review article from way back in 2002 and thought I’d share some of the highlights.  The authors seem very thorough; the article has 150 citations of other research articles. 

Note that the RDA – recommended dietary allowance – for protein is 0.8 gm/kg.  The typical U.S. resident eats about 1.2 gm/kg of protein daily, which is about 15% of total energy (calorie) intake.   Public health agencies recommend that we get 15% of our energy from protein, 30% from fat, and 55% from carbohydrate.  The authors of the study at hand propose that a high-protein diet be defined as:

  • protein intake of at least 25% of energy in weight-stable individuals, or
  • at least 1.6 gm/kg (of ideal body weight)  in people actively losing weight

Here are some of the authors’ points I found interesting:

  1. Higher-protein meals do seem to suppress hunger and enhance satiety, so high-protein dieters probably eat less (average 9% less calories).  It’s unknown if the effect lasts longer than six months.  Most of the evidences is much shorter-term.
  2. High-protein intake increases the thermic effect of feeding, meaning energy expenditure increases simply as a result of eating protein.  In other words, it takes energy to process the food we eat.  Compared with fats and carbohydrates, protein contributes twice as much to the thermic effect of feeding.  Most of the thermic effect of protein results from protein synthesis, i.e., the production of new proteins, which requires energy.  This has a minimal influence on body weight. 
  3. The authors write that “these studies do not support a role for high dietary protein in preventing loss of lean tissue during negative energy balance [actively cutting calories to lose weight], provided that dietary protein intake at least meets the RDA.”   
  4. They found only one study comparing a high-protein diet (25% of calories) with a low-fat, high-carbohydrate diet (12% protein).  Both diets were 30% fat.  Both groups could eat all they wanted.  Weight and fat loss were greater in the high-protein group, about twice as much. 
  5. High-protein diets over the long run may cause low-grade metabolic acidosis, leading to net loss of body calcium through the urine, with associated weak bones and kidney stones.   Animal proteins in particular do this.  Bone loss may be alleviated by calcium supplementation.  Fruits and vegetables may counteract the acidosis effect.  Nearly all of these statements are based on short-term studies.
  6. People with chronic kidney disease (ask your doctor) have slower disease progression and live longer if they limit protein to the RDA level. 
  7. Animal protein intake is directly related to risk of symptomatic kidney stones.
  8. Protein produces a blood glucose response, although not as much as with carbohydrate.  Insulin response is also seen.  In type 2 diabetics, the insulin response to 50 grams of animal protein was the same as to 50 grams of glucose.  A few studies suggest that in type 2 diabetics a high-protein diet may be detrimental to glucose control and/or insulin sensitivity.  Also note that people with diabetes are prone to chronic kidney disease, which could be worsened with a high-protein diet.  

Take-Home Points

See first paragraph.  The article authors may have different opinions now, based research published over the last seven years. 

Steve Parker, M.D.

Reference:  Eisenstein, Julie, et al.  High-protein weight-loss diets:  Are they safe and do they work?  A revew of the experimental and epidemiologic data.  Nutrition Reviews, 60 (2002): 189-200.

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Comparison of Mediterranean, Low-Carb, and Low-Fat Weight-Loss Diets

The July 17, 2008, issue of the New England Journal of Medicine has a well-done study comparing the Mediterranean, low-carb, and low-fat weight-loss diets in an Israeli population over the course of two years.  The researchers conclude that “Mediterranean and low-carbohydrate diets may be effective alternatives to low-fat diets.  The more favorable effects on lipids (with the low-carbohydrate diet) and on glycemic control (with the Mediterranean diet) suggest that personal preferences and metabolic considerations might inform individualized tailoring of dietary interventions.”

How was the study set up?

Moderately obese participants (322) were randomly assigned to one of the three diets: 1) low-fat, calorie-restricted, 2) Mediterranean, calorie-restricted, or 3) low-carbohydrate, non-restricted.  Calories in the low-fat and Mediterranean diets were “restricted” to 1800 per day for the men, 1500 for the women.  Average age of participants was 52, and average body mass index was 31.  [A 5-foot, 10-inch man weighing 216 pounds (98.2 kg) has a BMI of 31.]  Nearly all participants – 277 or 86% of the total – were men.  So there were only 45 women.  Forty-six participants had type 2 diabetes.

The low-fat diet was based on the American Heart Association guidelines of 2000: 30% of calories from fat [this isn’t very low], 10% of calories from saturated fat, cholesterol limited to 300 mg/day.  [The AHA revised their guidelines in 2006.]  Low-fat dieters ”were counseled to consume low-fat grains, vegetables, fruits, and legumes and to limit their consumption of additional fats, sweets, and high-fat snacks.”

The Mediterranean diet was based on the recommendations of Walter Willett and P.J. Skerrett as in their book, Eat, Drink, and be Healthy: The Harvard Medical School Guide to Health Eating.  Mediterranean dieters ate 2 fish meals per week, a handful of nuts daily, 30-45 grams of extra virgin olive oil per day, etc.  [One tablespoon of olive oil is 14 grams.]  The AHA states that “this diet reflects the current recommendations from the American Heart Association.”  There were no specific recommendations regarding alcohol in any of the diets.

The low-carb diet was based on  Atkins’ New Diet Revolution of 2002.  The goal was to provide 20 grams of carbohydrate per day for the 2-month induction phase, with a gradual increase to a maximum of 120 grams daily to maintain weight loss.  Total calories, protein, and fat were not limited.  “Participants were counseled to choose vegetarian sources of fat and protein….”

Whole grains were recommended for the low-fat and Mediterranean cohorts.

All participants worked at the same nuclear research facility in Dimona, Israel.  They were given careful instructions, initially and periodically, regarding the diet to which they were assigned.  Lunch is the main meal of the day in Israel, and they all ate lunch at the facility’s self-service cafeteria, which prompted them to choose the proper food items.  I assume they were told to maintain the diet when off-duty.  Adherence to the diets was assessed by a food-frequency questionnaire.

Findings

  • After 24 months, how many participants were still involved?  90% in the low-fat group, 85% in the Mediterranean, 78% in the low-carb.
  • There was little change in the usage of medications, and no significant differences among the groups.
  • Daily energy intake (calories or kcal) decreased from baseline levels significantly – about 450 calories – in all groups at 6, 12, and 24 months compared with baseline, with no significant differences among the groups in the amount of decrease.
  • All groups started with 51% of energy intake (calories) from carbohydrate.
  • At 24 months, the low-carb dieters were getting 40% of their daily calories as carbohydrates.  The other two groups were eating 50% of energy intake from carbs. [This still seems like a lot of carbs on the Atkins diet.  A gram of carbs has 4 calories.  The stated carbohydrate goal was a maximum of 120 grams of carbs daily, on a diet of 1800 calories.  So 120 grams of carbohydrate should be 27% of total daily calories.  At no point did the low-carb group reduce their average percentage of calories from carbohydrates under 40%.  OK, maybe be in the first two weeks but those data are not reported.  On an 1800 calorie diet, 40% of calories from carbs would be 180 grams.]
  • At 24 months, the low-carb dieters were getting 39% of their daily calories as fat.  The other two groups were in the 30-33% range.
  • Baseline fat intake for all groups was 31-32% of total calories, with saturated fat being 10% of the fat calories.
  • The low-fat cohort dropped their fat calories from 31 to 30% of total calories, which is essentially no change from baseline percentage.
  • At 24 months, the low-carbers were getting 22% of their daily calories from protein.  The other groups were at 19%.  [The low-carb Atkins diet is often criticized as having too much protein.]
  • Only the low-carb group made major changes in macronutrient composition of their diet.  Macronutrients are protein, fat, and carbohydrates.  This Atkins group increased saturated fat from 10 to 12% of total calories, reduced carbs from 51 to 40% of calories, increased protein from 19 to 22% of calories, and increased total fat from 32% to 39% or total calories.
  • All cohorts lost weight, but losses were greater in the low-carb and Mediterranean groups.  For the 272 participants who completed the full 24 months of intervention, the losses averaged 3.3 kg (7.3 lb) for the low-fat group, 4.6 kg (10.1 lb) for the Mediterraneans, and 5.5 kg (12.1 lb) for the low-carb group.
  • Among the 45 women, the low-fat group lost only 0.1 kg (0.22 lb), the Mediterraneans lost 6.2 kg (13.6 lb), and the low-carbers lost 2.4 kg (5.3 lb).  There were only 15, 20, and 10 women in these groups, respectively.
  • All groups had significant blood pressure reductions: about 4 mmHg systolic and 1 mmHg diastolic.
  • HDL cholesterol (the “good cholesterol”) increased in all groups, 8.4 mg/dl in the low-carb group, about 6.3 in the others.
  • LDL cholesterol (the “bad cholesterol”) fell 5.6 mg/dl in the Mediterraneans, 3.0 mg/dl in the low-carbers, and none in the low-fat group.  But these were not statistically significant differences between the groups.
  • The ratio of total to HDL cholesterol decreased for all groups, but the relative 20% decrease in the low-carb group was statistically significant compared to the 12% relative decrease in the low-fat group.  The ratio fell 16% in the Mediterranean group.  [The total/HDL ratio is thought to reflect risk of developing atherosclerotic complications.  You want it under 5 to 1, and 3.5 to 1 may be ideal.]
  • The level of high-sensitivity C-reactive protein decreased significantly only in the Mediterranean and low-carb cohorts.  [C-reactive protein is felt to be a marker of the systemic inflammation that has a role in atherosclerosis or hardening of the arteries.]
  • Thirty-six of the diabetics had adequate lab studies for analysis – about 12 in each diet group.  Only those in the Mediterranean group had a significant decrease in fasting glucose – 33 mg/dl.  The low-fat group had an increase.  Glycated hemoglobin decreased in all three groups although to a significant degree (0.9%) only in the low-carb group.  [High glycated hemoglobin levels reflect poor control of blood sugar levels in diabetics.]
  • Insulin levels decreased significantly in all three groups, diabetic or not.  [Abnormally high insulin levels are felt to have adverse health effects.]

Limitations of the study

  • Relatively few women, making it difficult to reliably generalize results to women.
  • Relatively few people with diabetes, making it difficult to reliably generalize results to people with diabetes.
  • Israeli gene pool?  Results not applicable to others?
  • No change in physical activity recommended to participants.  Increased exercise should enhance weight loss.

Take-Home Points

  • Caloric restriction leads to weight loss.
  • Mild degrees of weight loss reduce blood pressure.
  • In this study, the low-carb/Atkins and Mediterranean diets were more effective than the “low-fat” diet.
  • Atkins dieters can lose weight without counting calories, by limiting carbohydrate intake.
  • You gotta wonder if the low-carb group would have been even more successful if they had actually limited carbs to 120 grams daily.
  • It’s possible a lower-fat diet may have been more efficacious than the one utilized here.
  • This study did not enroll enough women to prove that a calorie-restricted Mediterranean diet is superior to low-fat and Atkins diets.  The greater weight loss – 13.6 pounds for Mediterranean versus 5.3 with Atkins – is suggestive and requires further study.
  • The average amounts of weight loss are not much when you think about the effort expended over 24 months of intervention.
  • These dieters reportedly reduced their daily caloric intake from baseline levels by about 450 calories, over the course of two years.  Yet they lost relatively little weight.  The numbers do not jive.  Most likely there is a problem with the methodology.  I doubt the average daily calorie deficit was as high as 450.
  • The Mediterranean diet seems to have been better for the people with diabetes.  Confirmatory studies are imperative.  Insulin resistance is an important factor in type 2 diabetes.  Monounsaturated fats, which are prominent in olive oil and the Mediterranean diet, are linked to improvement in insulin resistance in other studies.
  • For people who need to lose excess fat yet refuse to consciously restrict overall caloric  intake, the low-carb Atkins diet is a reasonable option.
  • The traditional Mediterranean diet has demonstrable long-term health benefits: longer lifespan, less cancer (colon, prostate, breast, uterus), reduction of cardiovascular disease, less dementia, and prevention of type 2 diabetes.  The Atkins diet cannot make those claims in 2008.

Steve Parker, M.D.

Reference:  Shai, Iris, et al.  Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet.  New England Journal of Medicine, 359 (2008): 229-241.

Additional information and critical analysis for health nuts like me:

Dr. Dean Ornish’s analysis in Newsweek online   Dr. Ornish is a leading low-fat diet advocate.

American Heart Association comments on the study in a July 19, 2008, news release

My additional comments:

The Mediterranean diet used in this study is based on Walter Willett’s 2001 book, Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating.  From the author:

I wrote this book to show you where the USDA Pyramid is wrong and why it is wrong.  I wanted to offer a new healthy eating guide based of the best scientific evidence, a guide that fixed the fundamental flaws of the USDA Pyramid and helps you make better choices about what you eat.  I also wanted to give you the latest information on new discoveries that shuould have profound effects on our eating patterns. 

Dr. Willett made a conscious decision not to call his new eating plan a Mediterranean diet.  Elsewhere in the book he notes that the Mediterranean diet pyramid promoted by Oldways Preservation and Exchange Trust is a good, evidence-based guide for healthy eating.  The entire book promotes Harvard’s Healthy Eating Pyramid, not the Mediterranean diet per se.

Harvard’s Healthy Eating Pyramid:

Harvard's Healthy Eating Pyramid

So were the Mediterranean dieters in the study at hand even following the Mediterranean diet?  The most glaring difference is Harvard’s lack of emphasis on olive oil.  Of lesser note is Harvard’s recommendation to eat white rice, white bread, potatoes, and refined-flour pasta only sparingly.  However, the researchers for this study directed Mediterranean diet participants to ingest 30-45 grams of olive oil per day.  After comparing the Harvard pyramid with the Oldways Mediterranean pyramid and other Mediterranean diet descriptions, it is fair to say the dieters here were indeed instructed on a Mediterranean diet.  In fact, the Mediterranean diet in this study is quite similar to the Advanced Mediterranean Diet.

Traditional healthy Mediterranean diet pyramid of Oldways Preservation and Exchange Trust:

Traditional healthy Mediterranean diet pyramid of Oldways Preservation and Exchange Trust

 

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Low-Carb Diet Beats Low-Fat, Calorie-Restricted Diet

Body mass index 38

Body mass index 38

I found one of the early studies (2003) demonstrating the effectiveness and safety of an Atkins-style diet in the severely obese.  Doctors traditionally have been hesitant to recommend the Atkins diet out of concern for tolerability and potential increased atherosclerosis complication such as heart attacks, strokes, and poor circulation.

Methodology

The study enrolled 132 subjects with an average body mass index of 43, including 77 blacks and 23 women.  39% had diabetes, 43% had metabolic syndrome.  They were randomly assigned to either . . .

  1. a low-carb diet without caloric restriction (carbohydrates limited to 30 gm/day; vegetables and fruits with high ratios of fiber to carbohydrate were recommended), or
  2. a low-fat, calorie-restricted diet. 

Subjects followed their diets for six months.  The researchers never specified, but I’m assuming the diabetics were all type 2. 

Results

The drop-out rate was equally high in both groups: only 79 subjects completed the study.  The low-carb group lost 5.8 kg (13 lb); the low-fat group lost 1.9 kg (4 lb).  Analysis included the drop-outs, for reasons unclear to me.  White subjects lost more weight than blacks: 13 versus 5 kg (29 versus 11 lb).  Total cholesterol, HDL cholesterol, and LDL cholesterol levels did not change significantly within or between groups.  [HDL usually rises on a low-carb diet.]   Triglycerides fell 20% in the low-carb group and 4% in the other group.  For subjects with diabetes, glucose levels fell 26 mg/dl in the low-carb group compared to 5 mg/dl in the low-fat group.  Uric acid levels didn’t change in either group.  [Elevated uric acid levels can cause gout.]  No significant adverse reactions attibutable to the diets were recorded in either group.  Glycosylated hemoglobin fell from 7.8 to 7.2% in the low-carb group, with no change in the low-fat group.   

Take-Home Points  

It’s a small study, so results may not be very accurate or generalizable to other populations.

In this cohort with a high prevalence of diabetes, the low-carb diet was more effective than the low-fat/calorie-restricted diet for weight loss, with no adverse lipid changes to suggest increased long-term cardiovascular risk.  The low-carb diet helped control diabetes. 

Steve Parker, M.D. 

Reference:  Samaha, Frederick, et al.  A low-carbohydrate as compared with a low-fat diet in severe obesity.  New England Journal of Medicine, 348 (2003): 2,074-2,081.

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Filed under Carbohydrate, Overweight and Obesity, Weight Loss