Tag Archives: ornish diet

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.

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

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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Filed under Carbohydrate, Overweight and Obesity