Category Archives: Weight Loss

June 23, 2009 · 2:00 AM

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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June 20, 2009 · 2:00 AM

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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May 25, 2009 · 9:31 AM

Spanish Ketogenic Mediterranean Diet

Altea, Plaça de la EsglésiaEver heard of the Spanish Ketogenic Mediterranean Diet?  It looks like a low-carb quasi-Mediterranean diet.

Researchers with the University of Cordoba in Spain studied 40 subjects eating a low-carb “Mediterranean” diet for 12 weeks.  The results were strikingly positive.

Methodology

A medical weight loss clinic was the source of 40 overweight subjects, 22 males and 19 females, average age 38, average body mass index 36.5, average weight 108.6 kg (239 lb).  These folks were interested in losing weight, and were not paid to participate.

Nine subjects were not included in the final analysis due to poor compliance with the study protocol (3), the diet was too expensive (1), a traumatic car wreck (1), or were simply lost to follow-up (4).  So all the data are pooled from the 31 subjects who completed the study.

Blood from all subjects was drawn just before the study began and again after 12 weeks of the diet.

Study diet:  Low-carbohydrate, high in protein [and probably fat, too], unlimited in calories.  Olive oil was the main source of fat (at least 30 ml daily).  Maximum of 30 grams of carbohydrates daily as green vegetables and salad.  200-400 ml daily of red wine.  The authors write:

Participants were permitted 3 portions (200 g/portion) of vegetables daily: 2 portions of salad vegetables (such as alfalfa sprouts, lettuce, escarole, endive, mushrooms, radicchio, radishes, parsley, peppers, chicory, spinach, cucumber, chard and celery), and 1 portion of low-carbohydrate vegetables (such as broccoli, cauliflower, cabbage, artichoke, eggplant, squash, tomato and onion).  3 portions of salad vegetables were allowed only if the portion of low-carbohydrate vegetables were not consumed.  Salad dressing allowed were: garlic, olive oil, vinegar, lemon juice, salt, herbs and spices.

The minimum 30 ml of olive oil were distributed unless in 10 ml per principal meal (breakfast, lunch and dinner).  Red wine (200–400 ml a day) was distributed in 100–200 ml per lunch and dinner.  The protein block was divided in “fish block” and “no fish block”.  The “fish block” included all the types of fish except larger, longer-living predators (swordfish and shark).  The “no fish block” included meat, fowl, eggs, shellfish and cheese.  Both protein blocks were not mixed in the same day and were consumed individually during its day on the condition that at least 4 days of the week were for the “fish block”.

Trans fats (margarines and their derivatives) and processed meats with added sugar were not allowed.

Vitamin and mineral supplements were given.

Subjects measured their ketosis state every morning with urine ketone strips.

Results (averaged)

  • Body weight fell from 108.6 kg (239 lb) to 94.5 kg (209 lb), or 2.5 pounds per week
  • Body mass index fell from 36.5 to 31.8
  • Systolic blood pressure fell from126 to 109 mmHg
  • Diastolic blood pressure fell from 85 to 75 mmHg
  • Total cholesterol fell from 208 to 187 mg/dl
  • LDL chol fell from 115 to 106 mg/dl
  • HDL chol rose from 50 to 55 mg/dl
  • Fasting glucose dropped from 110 to 93 mg/dl
  • Triglycerides fell from 219 to 114 mg/dl
  • No significant differences in male and female subjects
  • No adverse reactions are mentioned

Researchers’ Conclusions

The SKMD [Spanish Ketogenic Mediterranean Diet] is safe, an effective way of losing weight, promoting non-atherogenic lipid profiles, lowering blood pressure and improving fasting blood glucose levels.  Future research should include a larger sample size, a longer term use and a comparison with other ketogenic diets.

My Comments

The researchers called this diet “Mediterranean” based on olive oil, red wine, fish, and vegetables.

What’s “Not Mediterranean” is the paucity of carbohydrates (including whole grains); lack of yogurt, nuts, and legumes; and the high meat/protein intake.

The emphasis on olive oil, red wine, and fish could make this healthier than other ketogenic diets.

Ketogenic diets are notorious for high drop-out rates compared to other diets.  Most people can follow a ketogenic diet for only two or three months.  But several studies suggest greater short-term weight loss for people who stick with it.  Efficacy and superiority are little different from other diets as measured at one year out.

Many of the metabolic improvements seen here might be duplicated with loss of 30 pounds (13.6 kg) over 12 weeks using any reasonable diet.

Average fasting blood sugars in these subjects was 109 mg/dl.  Although not mentioned by the authors, this is in the prediabetes range.  The diet reduced average fasting blood sugar to 93, which would mean resolution of prediabetes.  Dropping body mass index from 36 to 32 by any method would tend to cure prediabetes.

Elevated blood sugar is one component of the “metabolic syndrome.”  Metabolic syndrome was recently shown to be reversible with a Mediterranean diet supplemented with nuts.

I suspect this would be a good program for an overweight person with uncontrolled type 2 diabetes, too.  But it has never been studied in a diabetic population.  So, who knows for sure?

If you’re thinking about doing something like this, get more information and be sure to get your doctor’s approval first.

Steve Parker, M.D.

Addendum:

On April 6, 2008, I had a delightful conversation with Jimmy Moore, of Livin’ La Vida Low-Carb fame regarding this study.  It struck me that the Spanish Ketogenic Mediterranean Diet is probably higher in protein and lower in fat than many other ketogenic weight-loss diets.  Since fish is emphasized over other animal-derived foods, it’s likely also lower in saturated fat.  [In low-carb diets, carbohydrates are substituted with either fats or proteins.]  I’m also convinced I will eventually have to review the validity of the dogmatic diet-heart hypothesis:  Dietary saturated fat, total fat, and cholesterol contribute to atherosclerosis and associated premature death from heart attacks and strokes.

References and Additional Reading:

Perez-Guisado, J., Munoz-Serrano, A., and Alonso-Moraga, A.  Spanish Ketogenic Mediterranean diet: a healthy cardiovascular diet for weight loss.  Nutrition Journal, 2008, 7:30.   doi:10.1186/1475-2891-7-30

Bravata, D.M., et al.  Efficacy and safety of low-carbohydrate diets: a systematic review.  Journal of the American Medical Association, 289 (2003): 1,837-1,850.

Gardner, C.D., et al.  Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A TO Z Weight Loss Study: a randomized trial.  Journal of the American Medical Association, 297 (2007): 696-677.

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, 140 (2004): 778-785.

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

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May 11, 2009 · 12:00 AM

High- vs Low-Protein Weight-Loss Diet in Type 2 Diabetes

 

Mucho protein, amigo

Mucho protein, amigo

A high-protein weight-loss diet yielded greater reduction in LDL cholesterol in both sexes, and greater loss of abdominal fat in overweight type 2 diabetics, compared to a lower-protein diet.  Lower LDL cholesterol levels are associated with lower risk of heart attack.

This scientific study caught my eye because it utilized a high-monounsaturated fat diet for weight loss.  The Mediterranean diet is rich in monounsaturated fats, mostly from olive oil.

Researchers in Australia ran a study to determine the effect of high- versus lower-protein wieght loss diets on fat and lean tissue, glucose levels, and blood lipids.  For perspective, remember that a typical American diet has about 15% of calories from protein, 30% from fat, and 55% from carbohydrates.

Methodology

This was their high-protein diet:  28% protein, 42% CHO, 28% fat (8% saturated fatty acids, 12% monounsaturated fatty acids, 5% polyunsaturated fatty acids).

The low-protein diet:  16% protein, 55% CHO, 26% fat (8% saturated fatty acids, 11% monounsaturated fatty acids, 5% polyunsaturated fatty acids).

They studied 54 obese men (19) and women (35) with type 2 diabetes during 8 weeks of energy restriction (1,600 kcal) and 4 weeks of energy balance.  Body composition was determined by dual-energy X-ray absorptiometry at weeks 0 and 12.

Results

Average weight loss for both groups was 5 kg.  However, women on the HP diet lost significantly more total (5.3 vs 2.8 kg) and abdominal (1.3 vs 0.7 kg) fat compared with the women on the LP diet, whereas, in men, there was no difference in fat loss between diets (3.9 vs 5.1 kg).  Total lean mass decreased in all subjects independently of diet composition.  LDL cholesterol reduction was significantly greater on the HP diet (5.7%) than on the LP diet (2.7%).  Blood glucose levels were reduced 5 or 10% by both diet interventions.  Trigylcerides dropped 20% in both groups.  Insulin concentrations were reduced in both groups.  Subjects lose 2.1% lean mass overall, with no difference between the groups.

Conclusions of the Study Authors

Both dietary patterns resulted in improvements in the cardiovascular disease (CVD) risk profile as a consequence of weight loss. However, the greater reductions in total and abdominal fat mass in women and greater LDL cholesterol reduction observed in both sexes on the HP diet suggest that it is a valid diet choice for reducing CVD risk in type 2 diabetes.

Take-Home Points

This was a relatively small study, so results may not be widely applicable.

Substituting proteins for carbs doesn’t seem to be detrimental to people with type 2 diabetes needing to lose weight, and may be advantageous:  greater total and abdominal fat loss in women, greater reductions in LDL cholesterol for both sexes.   At least in the short run.

Nephrologists will be concerned that the higher-protein diet, if sustained long-term, could lead to kidney damage.

Current dogma is that the lower-carb (high-protein) dieters should have had lower blood glucose, triglycerides, and HgbA1c levels:  not seen here.

Calorie-restricted diets tend to lower glucose levels and improve lipids, despite diet composition.

Reference:  Parker, Barbara et al.  Effect of a High-Protein, High–Monounsaturated Fat Weight Loss Diet on Glycemic Control and Lipid Levels in Type 2 Diabetes.  Diabetes Care,  25 (2002): 425-430.    From CSIRO Health Sciences and Nutrition, Adelaide, Australia.

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