Are Saturated Fats Bad For You?

Written by Dr. Steve Chaney on . Posted in Saturated Fats and Heart Disease

The Saturated Fat Wars Heat Up Again

Author: Dr. Stephen Chaney

Are saturated fats bad for you? 

are saturated fats bad for youI feel your pain. It is so confusing. Just a few months ago we were being told our fears of saturated fats were outdated. Saturated fats were fine. It was carbohydrates we needed to avoid.

Then, just last week the headlines blared: “Hold your horses. Saturated fats are bad for you. You need to avoid them.” No wonder you are confused!

Last week’s headlines were based on a recently published Presidential Advisory by the American Heart Association (F.M. Sacks et al, Circulation. 2017;135.00-00. DO!: 10.1161/CIR.0000000000000510). A Presidential Advisory is the AHA’s highest-level health advisory. It is meant to guide public health policy by government agencies such as the US Surgeon General’s office, the USDA, and the CDC.

However, the warnings about the dangers of saturated fat are very much like the warnings about the dangers of global warming. They have their believers and their deniers, and both sides passionately defend their positions. I understand the passion of saturated fat deniers. Foods high in saturated fat are an integral part of our heritage and our culture. It is only natural to want to believe those foods are good for us.

Because of this, I knew the AHA advisory would be controversial. After all, if someone is telling us we need to give up the foods we love, they better have darn good evidence to back up their recommendations.

I knew you, my readers, would want a scientifically accurate evaluation of the evidence, so I carefully analyzed the research studies the AHA presented in support of their recommendations. Here is what I found.

How Was The Analysis Done?

saturated fats and heart diseaseThis report was put together by the top heart disease experts, both physicians and research scientists, in the country. They examined over 50 years of research studies. They also examined meta-analyses that combined the results of multiple research studies. In short, they examined the entire body of scientific evidence on diet and heart disease.

The AHA committee used very rigorous criteria in selecting the best studies for their analysis. They only included randomized clinical trials that:

  • Had actual cardiovascular end points – heart attack, stroke, and deaths due to heart disease. Studies looking at things like LDL, HDL, particle size, inflammation etc. only give you part of the picture. They may, or may not, accurately predict risk of dying from heart disease.
  • Lasted two years or more. The fats we eat determine the fat composition of our cell membranes, and that is what ultimately determines our risk of dying from heart disease. This is the one instance it is true to say: “We are what we eat.”  However, changing the fat composition of our cell membranes does not occur overnight. It takes 2 years or more to achieve a 60-70% change in the fat composition of cell membranes.

It also takes time for any intervention to meaningfully impact heart disease risk. For example, with statin drugs it takes 1-2 years before there is a significant reduction in heart disease risk. Thus, for a variety of reasons, studies of less than 2 years duration are doomed to fail.

  • Showed the subjects stuck with the new diet for the duration of the study. Subjects find it difficult to adhere to a diet to which they are not accustomed long term and often revert to their more familiar diet. This requires either very close monitoring of what the subjects are eating or measurement of fat membrane composition to verify diet adherence, or both. Studies that only measured what the subjects were eating at the beginning of the study and then looked at outcomes months or years later may or may not be valid. Without any measurement of diet adherence, it is impossible to know.
  • Carefully controlled or measured what the saturated fats were replaced with. The importance of this criterion will be clear when we look at the results of their study.

They then did a meta-analysis of what they referred to as “core randomized trials” that met all 4 criteria. In short, this was a very rigorous and well-done analysis.

Are Saturated Fats Bad For You?

saturated fats from meatsThe main finding of the report was:

  • Replacing saturated fats from animal products with polyunsaturated fats from vegetable oils decreased the risk of heart disease by 29%. This is equivalent to statin therapy, without the side effects.
  • The conclusions of this report applied equally to the saturated fats that come from meats and dairy products.
  • About 50% of the risk reduction could be due to lowering of LDL cholesterol. The rest came from reduced arterial inflammation, increased flexibility of the arteries, increased membrane fluidity and other factors.
  • When the replacement of saturated fats with polyunsaturated fats occurred in the context of a heart healthy diet such as the Mediterranean diet, heart disease risk was reduced by 47%.

What the saturated fats are replaced with is critically important. The authors of this report calculated what would happen if we were to replace half of our saturated fat calories with equivalent calories from other foods. Replacing half of our saturated fat intake with:

  • Polyunsaturated fats (vegetable oils and fish oil), lowers heart disease risk by 25%.
  • Monounsaturated fats (olive oil & peanut oil), lowers heart disease risk by 15%.
  • Complex carbohydrates (whole grains, fruits & vegetables), lowers heart disease risk by 9%.
  • Refined carbohydrates and sugars (the kind of carbohydrates in the typical American Diet), slightly increases heart disease risk.
  • Trans fats, increases heart disease risk by 5%.
  • The authors did not address the relative value of omega-6 and omega-3 polyunsaturated fats in their report. However, I have addressed the heart health benefits of omega-3s in a previous report, Fish Oil Really Snake Oil.

Why Is There So Much Confusion?

saturated fats and LDL cholesterolYou are probably saying: “If saturated fats are so bad for me, why do I keep seeing diet books and news headlines saying I have nothing to fear from saturated fats?” The answer is pretty simple. The studies that have given rise to misleading headlines about the safety of saturated fats ignored one or more of the criteria described above that are needed to assure a valid conclusion. For example:

  • Some recent headlines claiming that saturated fats did not increase the risk of heart disease were based on studies in which saturated fats were replaced by refined carbohydrates and sugars. Other headlines were based on studies that did not measure what the saturated fats were replaced with.
  • The popular high saturated fat-low carb diets are not backed by any studies looking at their effect on heart attacks, stroke, or heart disease deaths. They are only backed by studies looking at their effect on LDL cholesterol and other imperfect markers of heart disease risk.
  • In contrast, the Mediterranean diet, which lowers saturated fat intake and contains healthy carbohydrates (whole grains, fruits and vegetables), significantly decreases the risk of heart disease. Please reference Mediterranean Diet for Heart Health.

 

What Are The Saturated Fat Deniers Saying?

 

saturated fats deniersThe saturated fat deniers have wasted no time trying to discredit the American Heart Association advisory. Maybe they can’t bear the thought of having to give up their favorite fatty foods. Or maybe they just can’t bear to admit they were wrong.

However, their claims just don’t hold water. Let me give you some examples.

  • The AHA (American Heart Association) is a tool of the pharmaceutical industry. If the AHA were a tool of the pharmaceutical industry, I hardly think their report would have stated that replacing saturated fats with polyunsaturated fats was as effective as statin drugs at reducing heart attack risk.
  • The AHA is a tool of the food industry. If the AHA were a tool of the food industry, I hardly think they would have recommended replacing fats from meat & dairy with polyunsaturated fats.
  • The AHA advisory was based on associations, which do not show cause and effect. False. The AHA committee based their recommendations on randomized clinical trials, the strongest kind of evidence. They merely said that studies looking at the association between saturated fats and heart disease were consistent with their analysis of randomized clinical trials.
  • The AHA advisory was based on LDL cholesterol, which is an imperfect predictor of cardiovascular risk. False. Again, the AHA committee based their recommendations on randomized clinical trials of cardiovascular outcomes, not on LDL levels. They merely estimated that LDL cholesterol levels contributed to about 50% of the risk they observed.
  • saturated fats mythsThe AHA committee ignored an early study in which replacing butter with polyunsaturated fats increased cardiovascular risk. False. That study actually replaced butter with margarine. It was the first study showing that trans fats are worse for us than saturated fats.
  • The AHA committee ignored recent studies that did not fit their hypothesis. False. They developed a valid set of scientific criteria for evaluating clinical studies. As described above, they simply eliminated those studies whose design does not permit a definitive conclusion.
  • The AHA recommends low fat diets containing refined carbohydrates and sugary foods, which are even worse. False. The AHA has consistently recommended low fat diets with complex carbohydrates (whole grains, fruits & vegetables). It is the food industry that corrupted their message. More to the point, this AHA Presidential Advisory specifically recommended lowering saturated fats in the context of a heart healthy diet like the Mediterranean diet.
  • The AHA recommends replacing saturated fats with omega-6 polyunsaturated vegetable fats, which can be harmful if consumed in excess. I have some sympathy with this argument. I would have preferred to have seen more emphasis on omega-3 oils in their report. There should also have been some discussion of the importance of antioxidants to protect against free radicals generated by polyunsaturated fat metabolism. However, their final recommendation to replace saturated fats with polyunsaturated fats in the context of a healthy diet like the Mediterranean diet goes a long way towards satisfying both concerns.

In short, the saturated fat deniers have no persuasive counter-argument. The evidence that saturated fat causes heart disease is simply overwhelming.

What Does This Mean For You?

replace saturated fats with polyunsaturated fatsThe time for debate is over. The evidence is overwhelming. It should be obvious to any reasonable person that saturated fats increase our risk of heart disease.

It should also be obvious that any diet that claims saturated fats are heart healthy is a myth. There are no long-term studies to back up that claim.

It is time to consider what it would mean if everyone in this country were to follow the AHA recommendations and replace half of the saturated fat in our diet with polyunsaturated fat. That would decrease our risk of heart disease by 29%.

  • 800,000 Americans die of heart disease each year. 232,000 lives would be saved.
  • Heart disease costs our nation $316 billion each year. $92 billion health care dollars would be saved.
  • Heart disease costs are expected to exceed $1 trillion by 2035. $290 billion health care dollars would be saved.

What if we decreased our risk of heart disease by 47% by coupling decreased intake of saturated fats with a heart healthy diet like the Mediterranean diet?

  • 376,000 lives would be saved.
  • $148 billion health care dollars would be saved.
  • $470 billion health care dollars would be saved by 2035.

Each of us has the ability to save our health and our lives by what we put into our mouths every day.

In addition, our health care system will soon become financially non-viable if we continue to focus on disease treatment rather than prevention. Each of us also has the ability to save our health care system by what we put into our mouths every day.

 

The Bottom Line

 

  • The link between saturated fat and heart disease risk is like global warming. It has its believers and its deniers, and both sides passionately defend their viewpoints.
  • The American Heart Association (AHA) recently released a Presidential Advisory on the relationship between saturated fats and heart disease. Because I knew their report would be controversial, I analyzed its scientific accuracy very carefully.
  • The AHA report was prepared by the top heart disease experts in the country. They reviewed over 50 years of clinical studies and used a very rigorous set of criteria to decide which studies to include in their analysis and which to exclude. In my judgement, the criteria they used were valid. Studies that fail to meet one or more of these criteria may not provide valid results. Unfortunately, several of the studies that have generated some of the recent controversy did not meet those criteria.
  • From a meta-analysis of “core studies” meeting these criteria, they concluded:
    • Replacing saturated fats from animal products with polyunsaturated fats from vegetable oils decreased the risk of heart disease by 29%. This is equivalent to statin therapy, without the side effects
    • The conclusions of this report applied equally to the saturated fats that come from meats and dairy products.
    • About 50% of the risk reduction could be due to lowering of LDL cholesterol. The rest came from reduced inflammation, increased flexibility of the arteries, and other factors.
    • When the replacement of saturated fats with polyunsaturated fats occurred in the context of a heart healthy diet such as the Mediterranean diet, heart disease risk was reduced by 47%.
  • The AHA recommends replacing half of the calories from saturated fat with healthier choices. From a detailed analysis of the data, the authors concluded which foods replace the saturated fat is very important. Replacing half of our saturated fat intake with:
    • Polyunsaturated fats (vegetable oils and fish oil), lowers heart disease risk by 25%.
    • Monounsaturated fats (olive oil & peanut oil), lowers heart disease risk by 15%.
    • Complex carbohydrates (whole grains, fruits & vegetables), lowers heart disease risk by 9%.
    • Refined carbohydrates and sugars (the kind of carbohydrates in the typical American Diet), slightly increases heart disease risk.
    • Trans fats, significantly increases heart disease risk.
  • The saturated fat deniers have already started trying to discredit the AHA advisory. I have reviewed their claims and found them to be baseless.
  • The evidence is overwhelming. It should be obvious to any reasonable person that saturated fats increase our risk of heart disease. It should also be obvious that any diet that claims saturated fats are heart healthy is a myth. There are no long-term studies to back up that claim.
  • If everyone in this country were to follow the AHA recommendations and replace half of the saturated fat in our diet with polyunsaturated fat:
    • Between 232,000 and 376,000 lives would be saved next year.
    • Between 92 and 148 billion health care dollars would be saved next year.
    • By 2035 between 290 and 470 billion health care dollars would be saved annually.

In short, each of us has the ability to preserve our health and save our lives by what we put into our mouth every day.

So, are saturated fats bad for you?  The answer is a resounding “yes.”

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.

Trackback from your site.

Comments (2)

  • Jim Campbell

    |

    Wonderfully, puts the controversy to rest.

    Reply

  • JoAnne Naro

    |

    Thank you Dr. Chaney. I always enjoy reading your very informative Health Tips. All the best to you and yours!

    Sincerely,
    JoAnne Naro
    Shaklee Associate

    Reply

Leave a comment

Recent Videos From Dr. Steve Chaney

READ THE ARTICLE
READ THE ARTICLE

Latest Article

A Low Carb Diet and Weight Loss

Posted January 15, 2019 by Dr. Steve Chaney

Do Low-Carb Diets Help Maintain Weight Loss?

Author: Dr. Stephen Chaney

 

low carb dietTraditional diets have been based on counting calories, but are all calories equal? Low-carb enthusiasts have long claimed that diets high in sugar and refined carbs cause obesity. Their hypothesis is based on the fact that high blood sugar levels cause a spike in insulin levels, and insulin promotes fat storage.

The problem is that there has been scant evidence to support that hypothesis. In fact, a recent meta-analysis of 32 published clinical studies (KD Hall and J Guo, Gastroenterology, 152: 1718-1727, 2017 ) concluded that low-fat diets resulted in a higher metabolic rate and greater fat loss than isocaloric low-carbohydrate diets.

However, low-carb enthusiasts persisted. They argued that the studies included in the meta-analysis were too short to adequately measure the metabolic effects of a low-carb diet. Recently, a study has been published in the British Medical Journal (CB Ebbeling et al, BMJ 2018, 363:k4583 ) that appears to vindicate their position.

Are low carb diets best for long term weight loss?

Low-carb enthusiasts claim the study conclusively shows that low-carb diets are best for losing weight and for keeping it off once you have lost it. They are saying that it is time to shift away from counting calories and from promoting low-fat diets and focus on low-carb diets instead if we wish to solve the obesity epidemic. In this article I will focus on three issues:

  • How good was the study?
  • What were its limitations?
  • Are the claims justified?

 

How Was The Study Designed?

low carb diet studyThe investigators started with 234 overweight adults (30% male, 78% white, average age 40, BMI 32) recruited from the campus of Framingham State University in Massachusetts. All participants were put on a diet that restricted calories to 60% of estimated needs for 10 weeks. The diet consisted of 45% of calories from carbohydrate, 30% from fat, and 25% from protein. [So much for the claim that the study showed low-carb diets were more effective for weight loss. The diet used for the weight loss portion of the diet was not low-carb.]

During the initial phase of the study 161 of the participants achieved 10% weight loss. These participants were randomly divided into 3 groups for the weight maintenance phase of the study.

  • The diet composition of the high-carb group was 60% carbohydrate, 20% fat, and 20% protein.
  • The diet composition of the moderate-carb group was 40% carbohydrate, 40% fat, and 20% protein.
  • The diet composition of the low-carb group was 20% carbohydrate, 60% fat, and 20% protein.

Other important characteristics of the study were:

  • The weight maintenance portion of the study lasted 5 months – much longer than any previous study.
  • All meals were designed by dietitians and prepared by a commercial food service. The meals were either served in a cafeteria or packaged to be taken home by the participants.
  • The caloric content of the meals was individually adjusted on a weekly basis so that weight was kept within a ± 4-pound range during the 5-month maintenance phase.
  • Sugar, saturated fat, and sodium were limited and kept relatively constant among the 3 diets.

120 participants made it through the 5-month maintenance phase.

 

Do Low-Carb Diets Help Maintain Weight Loss?

low carb diet maintain weight lossThe results were striking:

  • The low-carb group burned an additional 278 calories/day compared to the high-carb group and 131 calories/day more than the moderate-carbohydrate group.
  • These differences were even higher for those individuals with higher insulin secretion at the beginning of the maintenance phase of the study.
  • These differences lead the authors to hypothesize that low-carb diets might be more effective for weight maintenance than other diets.

 

What Are The Pros And Cons Of This Study?

low carb diet pros and consThis was a very well-done study. In fact, it is the most ambitious and well-controlled study of its kind. However, like any other clinical study, it has its limitations. It also needs to be repeated.

The pros of the study are obvious. It was a long study and the dietary intake of the participants was tightly controlled.

As for cons, here are the three limitations of the study listed by the authors:

#1: Potential Measurement Error: This section of the paper was a highly technical consideration of the method used to measure energy expenditure. Suffice it to say that the method they used to measure calories burned per day may overestimate calories burned in the low-carb group. That, of course, would invalidate the major findings of the study. It is unlikely, but it is why the study needs to be repeated using a different measure of energy expenditure.

#2: Compliance: Although the participants were provided with all their meals, there was no way of being sure they ate them. There was also no way of knowing whether they may have eaten other foods in addition to the food they were provided. Again, this is unlikely, but cannot be eliminated from consideration.

#3: Generalizability: This is simply an acknowledgement that the greatest strength of this study is also its greatest weakness. The authors acknowledged that their study was conducted in such a tightly controlled manner it is difficult to translate their findings to the real world. For example:

  • Sugar and saturated fat were restricted and were at very similar levels in all 3 diets. In the real world, people consuming a high-carb diet are likely to consume more sugar than people in the other diet groups. Similarly, people consuming the low-carb diet are likely to consume more saturated fat than people in the other diet groups.
  • Weight was kept constant in the weight maintenance phase by constantly adjusting caloric intake. Unfortunately, this seldom happens in the real world. Most people gain weight once they go off their diet – and this is just as true with low-carb diets as with other diets.
  • The participants had access to dietitian-designed prepared meals 3 times a day for 5 months. This almost never happens in the real world. The authors said “…these results [their data] must be reconciled with the long-term weight loss trials relying on nutrition education and behavioral counseling that find only a small advantage for low carbohydrate compared with low fat diets according to several recent meta-analyses.” [I would add that in the real world, people do not even have access to nutritional education and behavioral modification.]

 

low carb diet and youWhat Does This Study Mean For You?

  • This study shows that under very tightly controlled conditions (dietitian-prepared meals, sugar and saturated fat limited to healthy levels, calories continually adjusted so that weight remains constant) a low-carb diet burns more calories per day than a moderate-carb or high-carb diet. These findings show that it is theoretically possible to increase your metabolic weight and successfully maintain a healthy weight on a low-carb diet. These are the headlines you probably saw. However, a careful reading of the study provides a much more nuanced viewpoint. For example, the fact that the study conditions were so tightly controlled makes it difficult to translate these findings to the real world.
  • In fact, the authors of the study acknowledged that multiple clinical studies show this almost never happens in the real world. These studies show that most people regain the weight they have lost on low-carb diets. More importantly, the rate of weight regain is virtually identical on low-carb and low-fat diets. Consequently, the authors of the current study concluded “…translation [of their results to the real world] requires exploration in future mechanistic oriented research.” Simply put, the authors are saying that more research is needed to provide a mechanistic explanation for this discrepancy before one can make recommendations that are relevant to weight loss and weight maintenance in the real world.
  • The authors also discussed the results of their study in light of a recent, well-designed 12-month study (CD Gardener et al, JAMA, 319: 667-669, 2018 ) that showed no difference in weight change between a healthy low-fat versus a healthy low-carbohydrate diet. That study also reported that the results were unaffected by insulin secretion at baseline. The authors of the current study noted that “…[in the previous study] participants were instructed to minimize or eliminate refined grains and added sugars and maximize intake of vegetables. Probably for this reason, the reported glycemic load [effect of the diet on blood sugar levels] of the low-fat diet was very low…and similar to [the low-carb diet].” In short, the authors of the current study were acknowledging that diets which focus on healthy, plant-based carbohydrates and eliminate sugar, refined grains, and processed foods may be as effective as low-carb diets for helping maintain a healthy weight.
  • This would also be consistent with previous studies showing that primarily plant-based, low-carb diets are more effective at maintaining a healthy weight and better health outcomes long-term than the typical American version of the low-fat diet, which is high in sugar and refined grains. In contrast, meat-based, low-carb diets are no more effective than the American version of the low-fat diet at preventing weight gain and poor health outcomes. I have covered these studies in detail in my book “Slaying The Food Myths.”

Consequently, the lead author of the most recent study has said: “The findings [of this study] do not impugn whole fruits, beans and other unprocessed carbohydrates. Rather, the study suggests that reducing foods with added sugar, flour, and other refined carbohydrates could help people maintain weight loss….” This is something we all can agree on, but strangely this is not reflected in the headlines you may have seen in the media.

The Bottom Line

 

  • A recent study compared the calories burned per day on a low-carb, moderate-carb, and high-carb diet. The study concluded that the low-carb diet burned significantly more calories per day than the other two diets and might be suitable for long-term weight control. If confirmed by subsequent studies, this would be the first real evidence that low-carb diets are superior for maintaining a healthy weight.
  • However, the study has some major limitations. For example, it used a methodology that may overestimate the benefits of a low-carb diet, and it was performed under tightly controlled conditions that can never be duplicated in the real world. As acknowledged by the authors, this study is also contradicted by multiple previous studies. Further studies will be required to confirm the results of this study and show how it can be applied in the real world.
  • In addition, the kind of carbohydrate in the diet is every bit as important as the amount of carbohydrate. The authors acknowledge that the differences seen in their study apply mainly to carbohydrates from sugar, refined grains, and processed foods. They advocate diets with low glycemic load (small effects on blood sugar and insulin levels) and acknowledge this can also be achieved by incorporating low-glycemic load, plant-based carbohydrates into your diet. This is something we all can agree on, but strangely this is not reflected in the headlines you may have seen in the media.
  • Finally, clinical studies report averages, but none of us are average. When you examine the data from the current study, it is evident that some participants burned more calories per hour on the high-carb diet than other participants did on the low carb diet. That reinforces the observation that some people lose weight more effectively on low-carb diets while others lose weight more effectively on low-fat diets. If you are someone who does better on a low-carb diet, the best available evidence suggests you will have better long-term health outcomes on a primarily plant-based, low-carb diet such as the low-carb version of the Mediterranean diet.

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.

UA-43257393-1