Do Diets Work?

Written by Dr. Steve Chaney on . Posted in current health articles, Food and Health, Obesity

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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Comments (1)

  • Merlena Cushing

    |

    Thanks for this excellent article. You are truly a help to me in explaining these differences. Glad you had hyperlinks to your two previous articles, too. I have requested Corporate make further critique of the HFLC diets so I can refute those with precise rebuttal – piece by piece. They have been working on my request according to field services. It has been a week now. Hope to hear soon. Nedra told me when I asked (Nutrition Matters seminar) that to answer it in depth, she would need more time – a whole seminar session – approximately 1 1/2 hours.. She had recently been to a huge seminar on the “keto” diets.

    I’m adding this article to the many by you which address most of what I have needed.

    By the way, the hyperlink to your comments is not live (gives an error message) in case you wonder why you haven’t had any until now. I had to take a circuitous route to get to an article that said “LEAVE A COMMENT” at the bottom.

    Thanks again for all of the good you do! Blessings, Merlena

    Reply

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Latest Article

Best Diet For Heart Disease Prevention

Posted July 9, 2019 by Dr. Steve Chaney

Are The American Heart Association’s Recommendations Correct?

Author: Dr. Stephen Chaney

 

What is the best diet for heart disease prevention? 

diet for heart disease preventionHeart disease is a killer. It continues to be the leading cause of death – both worldwide and in industrialized countries like the United States and the European Union. When we look at heart disease trends, it is a good news – bad news situation.

  • The good news is that heart disease deaths are continuing to decline in adults over 70.
  • The decline among senior citizens is attributed to improved treatment of heart disease and more seniors following heart-healthy diets.
  • The bad news is that heart disease deaths are starting to increase in younger adults, something I reported in an earlier issue, Heart Attacks Increasing in Young Women of “Health Tips From the Professor.”
  • The reason for the rise in heart disease deaths in young people is less clear. However, the obesity epidemic, junk and convenience foods, and the popularity of fad diets all likely play a role.

Everyone has a magic diet for reducing heart disease risk. The American Heart Association tells us to avoid fats, especially saturated fats. Vegans tell us to avoid animal protein. Paleo and keto enthusiasts tell us carbs are the problem. Who is correct?

Of course, we don’t eat fats, carbohydrates, or proteins. We eat foods. That is why a recent study (T Meier et al, European Journal of Epidemiology, 34: 37-45, 2019) is so important. It reported which foods increase and which decrease the risk of premature heart disease deaths.

How Was The Study Done?

diet for heart disease prevention studyThe authors of the current study analyzed data from the “Global Burden of Diseases (GBD) Study”, a major world-wide effort designed to estimate the portions of deaths caused by various risk factors.

The current study focused on the impact of 12 dietary risk factors on heart disease deaths between 1990 and 2016 for 51 countries in four regions (Western Europe, Central Europe, Eastern Europe, and Central Asia).

The dietary risk factors were:

  • Diets low in fiber, fruits, vegetables, legumes, nuts and seeds, polyunsaturated fatty acids, omega-3 fatty acids, and whole grains.
  • Diets high in sodium, processed meats, sugar-sweetened beverages, and trans fatty acids.

Saturated fat and meat were not explicitly included in the GBS Study data. However, diets low in polyunsaturated fats and omega-3 fats are likely high in saturated fats. Similarly, diets low in fruits, vegetables, whole grains, and legumes are likely higher in meats. The study also did not include dairy, and some recent studies suggest that some dairy foods may decrease heart disease risk.

For simplicity I will only consider the findings from Western Europe because their diet and heart disease death trends are similar to those in the United States.

 

Best Diet for Heart Disease Prevention?

plant-based diet bestThe study found that in 2016 (the last year for which data were available):

  • Dietary risk factors were responsible for 49.2% of heart disease deaths.
  • 6% of all diet-related heart disease deaths occurred in adults younger than 70, and that percentage has been increasing in recent years.

When they looked at the contribution of individual foods to diet related heart disease deaths, the percentages were:

  • Diets low in whole grains = 20.4%
  • Diets low in nuts and seeds = 16.2%
  • Diets low in fruits = 12.5%
  • Diets high in sodium = 12.0%
  • Diets low in omega-3s = 10.8%
  • strong heartDiets low in vegetables = 9.0%
  • Diets low in legumes = 7.0%
  • Diets low in fiber = 5.7%
  • Diets low in polyunsaturated fats = 3.7%
  • Diets high in processed meats = 1.6%
  • Diets high in trans fatty acids = 0.8%
  • Diets high in sugar-sweetened beverages = 0.1%

So, what is the best diet for heart disease prevention?

In short, this study concluded:

  • A primarily plant-based diet is the best protection against premature death due to heart disease.
  • All plant-based food groups (whole grains, nuts and seeds, fruits, vegetables, and legumes) play an important role in reducing heart disease deaths.
  • Meat was not included in the analysis, but it is likely that most people’s diets in this region of the world contained some meat. The most likely take-away is that meat does not affect heart disease risk in the context of a primarily plant-based diet.
  • Dairy was not included in the analysis either, but some studies suggest dairy, particularly fermented dairy foods, reduce heart disease risk.
  • Finally, the study concluded: “Compared to other…modifiable risk factors (physical inactivity, drug and alcohol abuse, tobacco smoking, obesity, etc.), an altered diet is the most effective means of preventing premature deaths from cardiovascular disease in Western Europe.”

While every study has its weaknesses, this study is consistent with multiple previous studies showing that primarily plant-based diets are best for reducing heart disease risk. You will find a more complete discussion of these studies in my book “Slaying The Food Myths.”

 

Are the American Heart Association’s Recommendations Correct?

With this study’s results in mind we can now ask whether the recommendations of the American Heart Association and other popular diets are correct. Are they likely to reduce heart disease deaths?

  • The American Heart Association Recommends a dietary pattern that emphasizes a variety of fruits and vegetables, whole grains, nuts and legumes, skinless poultry and fish, and low-fat dairy products. This study supports those recommendations.
  • This study also supports the heart-health benefits of the Mediterranean and DASH diets.
  • Meat and dairy were not explicitly considered in this study. Thus, the results of this study are also consistent with vegan and semi-vegetarian diets.
  • However, low carb diets like Paleo and keto eliminate some of the key food groups (whole grains, fruits, and legumes) that appear to be essential for reducing heart disease risk. 40% of the heart-health benefits in this study came from those 3 food groups. Thus, this study does not support claims that those two diets are heart-healthy long term.

 

The Bottom Line

 

Everyone has a magic diet for reducing heart disease risk. The American Heart Association tells us to avoid fats, especially saturated fats. Vegans tell us to avoid animal protein. Paleo and keto enthusiasts tell us carbs are the problem. Who is correct?

A recent study provides some important clues. It looked at dietary patterns associated with reduced risk of premature death from heart disease in Western Europe. The study concluded:

  • A primarily plant-based diet is the best protection against premature death due to heart disease.
  • All plant-based food groups (whole grains, nuts and seeds, fruits, vegetables, and legumes) play an important role in reducing heart disease deaths.
  • Meat did not appear to affect heart disease risk in the context of a primarily plant-based diet.
  • Dairy was not included in the analysis, but some studies suggest dairy, particularly fermented dairy foods, reduce heart disease risk.
  • Finally, the study concluded: “Compared to other…modifiable risk factors (physical inactivity, drug and alcohol abuse, tobacco smoking, obesity, etc.), an altered diet is the most effective means of preventing premature deaths from cardiovascular disease.”

While every study has its weaknesses, this study is consistent with multiple previous studies showing that primarily plant-based diets are best for reducing heart disease risk. You will find a more complete discussion of these studies in my book “Slaying The Food Myths.”

With this study’s results in mind we can now ask whether the recommendations of the American Heart Association and other popular diets are correct. Are they likely to reduce heart disease deaths?

  • The American Heart Association Recommends a dietary pattern that emphasizes a variety of fruits and vegetables, whole grains, nuts and legumes, skinless poultry and fish, and low-fat dairy products. This study supports those recommendations.
  • This study also supports the heart-health benefits of the Mediterranean and DASH diets.
  • Meat and dairy were not explicitly considered in this study. Thus, the results of this study are also consistent with vegan and semi-vegetarian diets.
  • However, low carb diets like Paleo and keto eliminate some of the key food groups (whole grains, fruits, and legumes) that appear to be essential for reducing heart disease risk. 40% of the heart-health benefits in this study came from those 3 food groups. Thus, this study does not support claims that those two diets are heart-healthy long term.

For more details read the article above.

 

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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