Does the Blood Type Diet Really Work?

Written by Dr. Steve Chaney on . Posted in Food and Health, Issues

Is Eating Right For Your Blood Type A Sham?

Author: Dr. Stephen Chaney

cb43e76f-6bf7-4e82-8fc1-95005d2c5626Does the Blood Type Diet really work? In 1997 Dr. Peter J. D’Adamo wrote a book about the blood type diet called “Eat Right 4 Your Type”. Dr. D’Adamo claims that people with different blood types process food differently, so their blood type determines the type of diet that is healthiest for them. Specifically, he claims that people with:

  • Blood group O are descended from hunters and should consume high protein diets.
  • Blood group A are descended from farmers and should consume a near vegetarian diet – completely avoiding red meats.
  • Blood group B are descended from nomads. They have the most flexible digestive system and can eat the widest variety of foods – even dairy products, which he does not recommend for any of the other blood types.
  • Blood group AB are an enigma and are somewhere between blood group A and blood group B.

It’s an interesting concept. Dietary recommendations are made for populations as a whole, and there is tremendous genetic variation in populations. Because of that genetic variation, there is no perfect diet for everyone. Every knowledgeable health expert will tell you that.

The question then becomes “How do you know what kind of diet is healthiest for you?”

The blood type diet is a very simple system. Your blood type is easy to determine. Once you know your blood type you know what to eat. There’s no guesswork.

Could it really be so simple? Over 7 million copies of Dr. D’Adamo’s book have been sold. Millions of people believe in this concept. So it is only fitting to ask “What is the evidence?”

An Objective Scientific Analysis of the Blood Type Diet

There is no doubt that blood type is related to some human genetic and physical traits, but the important question is whether blood type is related to the health outcomes of different diets – the central thesis of Dr. D’Adamo’s book. A Belgian group lead by Dr. Emmey De Buch did a systematic search of the scientific literature to answer that very question (L. Cusack et al, Am J. Clin. Nutr. , 98: 99-104, 2013).

They identified 1415 scientific articles that had the phrase “blood type diet” in either the title or abstract. Then they begin the elimination process. They eliminated:

  • Studies done in test tubes, cell culture, or animals. Only human clinical studies were included.
  • Reviews, commentaries, letters or opinions. Those contained no original scientific research.

At this point they were down to just 16 published clinical studies. Then they asked which of those studies were designed to test the central hypothesis of the blood type diet. They asked:

  • Did the study start with human subjects grouped according to blood type?
  • Did the study have an intervention in which the subjects were required to adhere to a particular type of diet?
  • Did the study measure a health outcome of the dietary intervention?

Guess what? Only one study met these criteria. Just one! And it was a fairly weak study involving a totally different blood typing system than the ABO blood groups.

The Bottom Line:

1)     There is no scientific evidence supporting the blood group diet. A lot has been written about the diet, but nobody has actually shown that it works. The Emperor Has No Clothes!

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Latest Article

Do Diets Work?

Posted December 16, 2014 by Dr. Steve Chaney

dietingObesity in America?

Author: Dr. Stephen Chaney

If you are like most Americans, you are either overweight yourself or have close friends and family who are overweight. That’s because 69% of Americans are currently overweight, and 36% of us are obese. Worldwide the latest estimates are that 1.5 billion adults are overweight or obese.

A new report, How The World Could Better Fight Obesity,  estimates that obesity is a $2 trillion drain on the world’s economy. That is equivalent to the global cost of war & terrorism and of smoking – and is double the global costs of alcoholism and global warming!

If you are like most Americans you have tried a number of diets over the years. All of them promised that they had the “secret” to permanent weight loss. You lost some weight initially, but here you are a few years later weighing as much as ever.

You are probably beginning to wonder whether any diets work long term. According to the latest study, the answer may just be “no”.

Really, Do Diets Work?

This study (Atallah et al, Circulation Cardiovascular Quality and Outcomes, 7: 815-827, 2014) was a systemmatic review of all of the randomized controlled studies of the four most popular diet plans – Weight Watchers, Akins, Zone and South Beach.

In case, you are unfamiliar with these diets, here is their philosophy:

  • Weight watchers is a food, physical activity and behavior modification plan that utilizes a point system to control calorie intake and features weekly group sessions.
  •  Atkins is based on very low carbohydrate intake, with unlimited fat and protein consumption.
  •  South Beach is relatively low carbohydrate, high protein diet that focuses on low-glycemic index carbohydrates, lean proteins, and mono- and polyunsaturated fats.
  • Zone is a low carbohydrate diet that focuses on low-glycemic load carbohydrates, low-fat proteins and small amounts of good fats.

The investigators restricted their analysis to studies that were greater than 4 weeks in duration and either compared the diets to “usual care” or to each other. (The term usual care was not defined, but most likely refers to a physician giving the advice to eat less and exercise more).

Twenty six studies met their inclusion criteria. Fourteen of those studies were short-term (< 12 months) and 12 were long-term (>12 months). Of the long-term studies, 10 compared individual diet plans to usual care and 2 were head-to-head comparisons between the diet plans (1 of Atkins vs Weight Watchers vs Zone and 1 of Weight Watchers vs Zone vs control). The majority of participants in these studies were young, white, obese women. Their average age was 45 years and their average weight at the beginning of the studies was 200 pounds.

What Did This Study Show?

If you have struggled with your weight in the past, you probably won’t be surprised by the result of the study.

  •  Short-term weight loss was similar for Atkins, Weight Watchers and Zone in the two head-to-head studies.
  •  At 12 months, the 10 studies comparing individual diets to usual care (physician’s advice to eat less and exercise more) showed that only Weight Watchers was slightly more effective than usual care (physician’s advice to lose weight). The average weight loss at 12 months was 10 pounds for Weight Watchers and 7 pounds for usual care. That is a 3 pound difference for all of the additional effort and expense of Weight Watchers!
  • When they looked at the two head-to-head studies at 12 months, there was no significant differences between the diets. Average weight loss in these studies was 7 pounds for Weight Watchers, 7 pounds for Atkins, 5 pounds for Zone and 5 pounds for usual care. There was only one study comparing the South Beach diets with usual care. It was a study comparing the results with severely obese patients following gastric bypass surgery, and it also found no difference between the diet program and usual care. Based on hype about these diets, you were probably expecting more than a 5 to 7 pound weight loss 12 months later!
  •  By 24 months 30-40% of the weight had been regained for the Atkins and Weight Watchers diets, which was comparable to the results for patients who were just told to eat less and exercise more. Not only was the weight loss modest, it also did not appear to be permanent.
  •  Finally, many of the studies included in this review also looked at improvement in other health parameters such as HDL cholesterol levels, LDL cholesterol levels, triglycerides, blood pressure and blood sugar control. The Atkins diet gave slightly better results with HDL levels, triglyceride levels and blood pressure in the short-term studies, but there was no significant differences for any of these parameters in the long-term head-to-head studies. None of the diets were any healthier than the others.

The investigators concluded: “Our results suggest that all 4 diets are modestly efficacious for short-term weight loss, but that these benefits are not sustained long-term.

A similar study in 2005 compared the Weight Watchers, Jenny Craig and LA Weight Loss diets (Tsai et al, Annals of Internal Medicine, 142: 56-66, 2005) and concluded “…the evidence to support the use of major commercial and self-help weight loss programs is suboptimal”.

weight loss and obesityA Weight Loss Diet That Actually Works?

My personal recommendation for the initial weight loss is a high protein diet – one that provides about 30% of calories from healthy protein and moderate amounts of healthy carbohydrates and healthy fats. The protein should be high enough quality so that it provides 10-12 gram of the essential amino acid leucine because leucine specifically stimulates muscle growth. The combination of high protein and leucine preserves muscle mass while you are losing weight. That is important because it keeps your metabolic rate high without dangerous herbs or stimulants.

However, the high protein, high leucine diet is still just a diet. It is an excellent choice for the initial weight loss, but what about long-term weight control?

The authors of this study said: “Comprehensive lifestyle interventions aimed at curbing both adult and childhood obesity are urgently needed. Interventions that include dietary, behavioral and exercise components…may be better suited to [solve] the obesity epidemic.” I agree.

The Bottom Line:

Your suspicions are correct. Diets don’t work!

A recent systematic review of 26 randomized controlled clinical trials of the Weight Watchers, Atkins, Zone & South Beach diets compared to the usual standard of care (recommendations to eat less and exercise more) concluded:

1) Contrary to what the advertisements promise, after 12 months all four diets gave comparable and very modest (5-7 pounds) total weight loss. The results with the diets were not significantly different than for patients who were simply told to eat less and exercise more.

2) By 24 months 30-40% of the weight had already been regained.

3) A previous systematic review of the Weight Watchers, Jenny Craig, and LA Weight Loss diet programs came to a similar conclusion.

4) My personal recommendation for the initial weight loss is a diet that is high in protein and the amino acid leucine because that type of diet preserves muscle mass.

5) For permanent weight control the authors of the recent systematic review recommended comprehensive lifestyle interventions that include permanent changes in diet, behavior and exercise. I agree. Diets never work long term – lifestyle change does!

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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