Dr. Willett does recommend less saturated fat and more mono- and poly-unsaturated fat, although he quotes studies that say that saturated fat had no effect on heart disease risk, but his overall opinion is music to the lowcarbers ears--that people should stop making sweeping comments about eating fat being bad. He shows that a low-fat diet increases risk of heart disease and that replacing saturated fat with carbs also increases risk of heart disease.

Proc Soc Exp Biol Med 2000 Dec; 225(3):187-90.

Will High-Carbohydrate/Low-Fat Diets Reduce the Risk of Coronary Heart Disease?

Walter C. Willett
Chairman of the Department of Nutrition, Harvard

…During the 1980s, a subtle shift developed in dietary recommendations that led to an emphasis on reducing fat intake in general, with less distinction about the type of fat. Thus, the first recommendation of the American Heart Association became to reduce total fat intake, and similar emphasis on total fat reduction has been part of the general US dietary guidelines as well. This emphasis on total fat reduction is epitomized by the U.S. dietary pyramid, which indicates that all types of fat should be used sparingly, and complex carbohydrates should be consumed in large amounts. . .

Although replacement of total and saturated fat with carbohydrate has been at the centerpiece of recommendations to reduce heart disease, the degree of risk reduction to be expected has received little attention. Recently, the Nutrition Committee of the American Heart Association provided an estimate of the reduction in risk that would be expected were the total U.S. population to decrease their intake of saturated fat to the Step 1 goal of 10% of energy. This calculation involved a two-step process using data from controlled feeding studies to estimate the effect of saturated fat reduction on serum cholesterol to risk of coronary heart disease. The committee concluded that “equations developed from carefully conducted clinical studies indicate that reducing saturated fat from the current average intake of 12% to 14% of calories can lead to an average reduction of 3% to 5% in CHD risk in the population as a whole.” One might reasonably ask whether such a modest reduction should be a sufficient reason for individuals to make major changes in their life, but there is good reason to suspect that even this estimate may be a serious overstatement because the same dietary change will have an adverse effect on lipid fractions other than total serum cholesterol.

The effect on blood lipids of replacing saturated fat with carbohydrate has been evaluated in numerous controlled feeding studies with consistent results. With this dietary change, serum total cholesterol and LDL decline, but HDL cholesterol also decreases, and triglyceride levels are elevated. Thus, the ratio of total cholesterol divided by HDL is minimally affected by replacing saturated fat with carbohydrate, suggesting that there is little if any benefit to be expected. On the other hand, replacing saturated fat with olive oil or another fat high in mono-unsaturated fatty acids produces a similar decline in total and LDL cholesterol, but HDL cholesterol is not reduced, and triglycerides do not increase. Thus, these lipid changes would predict that the replacement of saturated fat with carbohydrate would have little effect on CHD risk, but that replacement with monounsaturated fat would be beneficial. The adverse effects of high-carbohydrate intake appear to be worse among individuals with underlying insulin resistance, as would be expected in a population that was over-weight an sedentary.

The effects of dietary fats on blood lipid fractions are further complicated because the isomeric position of double bonds can have a major impact on function of fatty acids including their effects on blood lipids. In a controlled feeding study, Mensink and Katan found that, compared with monounsaturated fat, trans fatty acids and saturated fat had similar effects on LDL cholesterol, but trans fat uniquely lowered HDL cholesterol. Thus the adverse effect of trans fat on the total cholesterol to HDL ratio was approximately twice as detrimental as that of saturated fat. This finding has been reproduced consistently in other metabolic studies, and further evidence indicates that trans fatty acids modestly elevate serum triglycerides and increase Lp(a) compared with saturated fat.

The effects of dietary fat on blood lipids described above would suggest that reduction in fat intake per se is not likely to be beneficial. Further, were monounsaturated or polyunsaturated fats replaced with carbohydrate, risk of coronary heart disease might actually be increased. …

…We recently also documented that total fat intake as a percentage of calories was strongly inversely associated with fasting blood triglyceride levels as predicted by metabolic studies (unpublished data)….

[Note: This last sentence means in English that the less your percentage of fat in your diet is the higher your triglycerides i.e. inversely associated (the more of one thing, the less of the other)]

…total fat intake was not associated with risk of coronary heart disease….

Similarly, substitution of saturated fat with carbohydrates was associated with only a small and not statistically significant lower risk….

[Note: This last sentence means that there is absolutely no difference in lowering risk of heart disease if you take saturated fat out of the diet and substitute it with carbs. Not statistically significant means that it is within the margin for error (the standard deviation) which means it has no meaning statistically.]

…The notion that total fat intake is not an important risk factor for coronary heart disease may appear heretical as this is inconsistent with the general advice conveyed to the U.S. public. However, it is hardly a revolutionary conclusion. The Executive Summary of the major 1989 review on diet and health by the National Academy of Sciences concludes that “intake of total fat per se, independent of the relative content of different types of fatty acids, is not associated with high blood cholesterol levels and coronary heart disease”. In particular, this message is inconsistent with the emphasis on total fat reduction in the U.S. dietary pyramid. The likelihood that coronary heart disease risk will actually be increased by replacing mono- and poly-unsaturated fats with carbohydrate is important because unsaturated fats actually comprise the majority of dietary fat in the United States….

…On the basis of metabolic and epidemiologic evidence, replacing unsaturated fats with carbohydrates would be expected to increase risk of coronary heart disease. However, some have argued that decreasing the percentage of energy from fat in the diet will reduce weight importantly, so that the overall effect would be beneficial. Despite this argument, an important benefit of dietary fat reduction on body weight has not been supported in longer-term, randomized trials. …However, in studies lasting one or more years, the weight loss described above appears to be transient, and the effect on weight over the longer time is minimal, typically about 1-3kg. …Although more research is needed on the effects of long-term fat intake on body weight control, the available evidence is quite clear that there will be little if any effect on body weight with reductions in dietary fat, at least over the range of about 18%-40% of energy from fat.
Although further studies are warranted relating specific types of fat to risk of coronary heart disease, the available evidence suggests several conclusions. First, coronary heart disease rates can be dramatically reduced by nutritional means, but this will not be achieved by replacing saturated fat with carbohydrates. Second, we should abandon recommendations regarding the percentage of energy from fat and pejorative references to fat or fatty foods. Finally, advice about dietary fat should focus on replacement of saturated and trans fatty acids with unsaturated fats, including sources of alpha-linolenic acid.

Voyajer--

You're doing yeoman service! Bless you!

Sheldon

Thanks Sheldon. What a nice boost for the day!

I wanted to add that the American Heart Association was obliged to change its usual support the food pyramid guidelines in 2000 probably as a response to Willett's article:

The Revised Dietary Guidelines parroted the existing food pyramid 6 servings grain besides 5 servings fruits and vegetables, low-fat mumbo jumbo, but had to add this little addendum in view of recent research:

"3. Diets With Extremes of Macronutrient Intake

"a. High Unsaturated Fat Diets
In conjunction with an energy intake suitable for maintaining a normal body weight, a diet high in unsaturated fat and low in saturated fat can be a viable alternative to a diet that is very low in total fat, particularly in individuals with an atherogenic dyslipidemia characterized by low HDL cholesterol, elevated triglycerides, and small dense LDL.118 This dietary approach entails replacing saturated fat calories with unsaturated fat calories rather than carbohydrate calories. A diet high in unsaturated fat may provide up to 30% of calories from monounsaturated and polyunsaturated fat, <10% of calories from saturated fat, and <300 mg/d of cholesterol. As noted above, there is now clear evidence that total and LDL cholesterol levels are reduced comparably by replacement of saturated fat with either unsaturated fat or carbohydrate during weight maintenance conditions. Moreover, a diet relatively high in unsaturated fat can prevent or attenuate the decrease in HDL cholesterol and the increase in triglycerides that can occur in some individuals’ response to a high-carbohydrate, lower-fat diet. 118 These latter effects may confer additional cardioprotective effects beyond LDL cholesterol lowering. Implicit to recommending a high unsaturated fat diet is that a healthy body weight be achieved and maintained.

"b. Very-Low-Fat Diets
Although in certain individuals under physician supervision, very-low-fat diets may lead to weight loss and improved lipid profiles,143 144 145 they are not recommended for the general population for several reasons. First, results of randomized trials show that weight loss is not sustained.143 146 Second, in extreme cases, very-low-fat diets may lead to nutritional inadequacies for essential fatty acids. Third, very-low-fat diets are often associated with the use of processed low-fat foods that are calorie dense.147 Finally, in individuals with certain metabolic disorders associated with increased coronary disease risk, namely low HDL cholesterol, high triglyceride, and high insulin levels, a very-low-fat diet can amplify these abnormalities,148 149 150 and other more appropriate dietary approaches are indicated, as described above."

http://circ.ahajournals.org/cgi/content/full/4304635102

J Am Coll Nutr 2001 Feb; 20(1):5-19

Types of dietary fat and risk of coronary heart disease: a critical review.

Hu FB, Manson JE, Willett WC.

During the past several decades, reduction in fat intake has been the main focus of national dietary recommendations to decrease risk of coronary heart disease (CHD). Several lines of evidence. however, have indicated that types of fat have a more important role in determining risk of CHD than total amount of fat in the diet. Metabolic studies have long established that the type of fat, but not total amount of fat, predicts serum cholesterol levels. In addition, results from epidemiologic studies and controlled clinical trials have indicated that replacing saturated fat with unsaturated fat is more effective in lowering risk of CHD than simply reducing total fat consumption. Moreover, prospective cohort studies and secondary prevention trials have provided strong evidence that an increasing intake of n-3 fatty acids from fish or plant sources substantially lowers risk of cardiovascular mortality. In this article, we review evidence from epidemiologic studies and dietary intervention trials addressing the relationship between dietary fat intake and risk of CHD, with a particular emphasis on different major types of fat, n-3 fatty acids and the optimal balance between n-3 and n-6 fatty acids. We also discuss the implications of the available evidence in the context of current dietary recommendations.

Key teaching points:
1. In the past several decades, reduction in fat intake has been the main focus of national dietary recommendations to lower risk of coronary heart disease (CHD).
2. Metabolic studies have long established that the type of fat, but not total amount of fat, predicts serum cholesterol levels.
3. Results from epidemiologic studies and controlled clinical trials have indicated that replacing saturated fat with unsaturated fat is more effective in lowering risk of CHD than simply reducing total fat consumption.
4. Prospective cohort studies and secondary prevention trials have provided strong evidence that a higher intake of n-3 fatty acids from fish or plant sources lowers risk of CHD.
5. Recent national dietary guidelines have shifted the emphasis from total fat reduction to distinguishing different types of fat.

INTRODUCTION
During the past several decades, reduction in fat intake has been the main focus of national dietary recommendations. In the public’s mind, the word “dietary fat” has become synonymous with obesity and heart disease, whereas the words “low-fat” and “fat-free” have become synonymous with heart health. In response to the low-fat campaign, the food industry has produced numerous commercial products labeled as “low-fat” or “fat-free,” but with high amounts of refined carbohydrates and sugar. Ironically, while dietary fat intake as percentage of energy intake has declined in the US over the years, total caloric intake has not declined, and the prevalence of obesity and type 2 diabetes has grown dramatically.
It is now increasingly recognized that the low-fat campaign has been based on little scientific evidence and may have caused unintended health consequences. It is also increasingly appreciated that different types of fats have different health effects. …
MAJOR TYPES OF DIETARY FAT
A higher intake of total and saturated fat is widely believed to contribute to the development of CHD. This belief is largely based on ecological studies relating dietary intake of saturated fat and rates of CHD. In the Seven Countries Study, intake of saturated fat as a percentage of calories was strongly correlated with coronary death rates across 16 defined populations in seven countries. Interestingly, the correlation between the percentage of energy from total fat and CHD incidence was much weaker. Indeed, the regions with the highest CHD rate (Finland) and the lowest rate (Crete) had the same amount of total fat intake, at about 40% of energy which was the highest among the 16 populations….
….
A major purported benefit of a low-fat diet is weight loss. But long-term clinical trials have not provided convincing evidence that reducing dietary fat can lead to substantial weight loss. On the contrary, there is some evidence that a diet containing a high amount of refined carbohydrates may increase hunger and promote overeating, which can lead to weight gain and obesity. It is now generally agreed that total energy intake, whether from fat or carbohydrate, relative to energy expenditure, is a more important determinant of body weight than dietary fat per se.
It has been increasingly recognized that the widely promoted low-fat concept is too simplistic and not compatible with available scientific data. ….
However, due to the campaign against total fat over the years, the belief that “fat is bad” has been strong and widespread. Thus, great educational efforts are needed to communicate nutritional messages about the health effects of different types of fat to the public and to translate current dietary recommendations into dietary practice as well.

Voyajer--

This is powerful stuff. Willett is obviously a prominent authority. Does what he have to say make an impact where it matters? One would think that when the chairman of Harvard's department of nutrition says that total fat doesn't matter and that substituting carbs for fat is self-defeating, people would listen. Is the entrenched establishment that strong?

Sheldon

According to an expert nutritionist Dr. Mary Enig, the anti-fat campaign began in the 1950s. It wasn't until the 1980s that it took hold of the country though. The government promoted anti-fat even when there were no scientific studies to back the claim. I doubt if the government will listen to scientific studies at this point either. Dr. Willett himself says that it will take time. He has influenced the new dietary guidelines a little. The government's dietary guidelines still strongly promote low-fat diets. But there are two tiny paragraphs at the end of the document that say that if your HDL is low, you should try a high monounsaturated fat diet and another paragraph that says that low-fat diets less than 15% fat can be dangerous. That's the extent of it. It could be years until the public catches on. I'm not holding my breath.

Thanks again, Voyajer. Do you part ways with Willett when it comes to saturated fat? I recall reading on Atkins's site that Dr. Atkins advises people to be careful with saturated fat until more research is done. Is that your understanding? Did I misread something? I also noticed that Diana Schwarzbein suggests watching saturated fat when trying to lose weight. Otherwise, I believe she puts no restrictions on it.

What's your view on all this? I'd be interested to hear it.

Regards,
Sheldon

I suppose the reason I've done all this research is to answer that one question. Should saturated fat be avoided?

The answer to: "Is saturated fat bad for you?" is easy. The answer is unequivocally NO. Saturated fat is a natural component of animal products. Humans evolved eating animal products. Humans would not have evolved a higher brain unless they ate animal products. Does saturated fat hurt you? No. It's good for you.

Should it be avoided? The answer should be no. Dr. Mary Enig and the entire Weston A Price foundation and their followers as well as many, many low-carb groups say saturated fat should not be avoided and in some cases they say it should be the primary fat that we eat.

I for the most part agree with this.

However, my studies have led me to believe that there is unmistakable evidence that some saturated fats can raise total cholesterol. This has worried me from the beginning. Not for people with normal cholesterol. I think people with cholesterol under 250 should not avoid saturated fat for many reasons. One, because we were meant to eat saturated fat. Two, because atherosclerosis is caused by fat oxidation and saturated fat is the least likely to oxidize. Three, because saturated fat is always integrated with other fats. Four, because I've eaten a ton of saturated fat and my cholesterol is 168 and my HDL is 71. Five, because cholesterol under 160 leads to suicide, stroke and cancer. Six, because high HDL is the best protection against heart disease and saturated fat raises HDL the most.

However, I believe there are certain people with high cholesterol who even when low-carbing have a problem lowering their cholesterol to under 275. Even though high cholesterol may have nothing whatsoever to do with atherosclerosis, the charts and graphs appear to show that those with cholesterol levels over 275 are at higher risk for heart disease.

Let me explain here. This does not mean that high cholesterol causes heart disease. Two hundred years ago, a doctor may have said that a person died of The Fever. But what caused the fever? What did they die of? The fever was a symptom that something was wrong in the body. They really died of a bacteria
or virus that the doctor wasn't medically advanced enough to know about. Doctor's thought, "Fever kills, so bring the fever down." But what was the real cause of death? The same is true of high cholesterol. Those with extremely high cholesterol are more likely to die of heart disease, but high cholesterol is like the fever. It is merely a symptom that the body is out of balance. Something unknown is going on that is causing heart disease and a symptom is high cholesterol. But just as bringing down a fever doesn't cure the disease, neither does bringing down cholesterol necessarily cure heart disease.

But let's say that a person's cholesterol is over 275 signalling an imbalance in the body showing that something is making them at greater risk for heart disease. Now here is the kicker. If they have been on a low-fat diet, they will undoubtably lower their cholesterol by eating a great quantity of saturated fat. This is what happens to most people who low-carb. This is because it is the sugar (glucose) that gave them high cholesterol in the first place. But in a minority of cases, some people do not lower cholesterol by eating saturated fat and for those very few and far in between, I would suggest cutting down on the saturated fat for a time to see if it is the problem.

It is hard to make sweeping statements about anything when it comes to the body. Our bodies all react differently and we are all individuals.

However, in spite of what Dr. Willett appears to believe and in spite of or rather because of all the studies I've read, I truly believe that saturated fats are beneficial for most people and should not be avoided. I think we all feel the pressure of years of brain-washing--even Dr. Willett feels it, even Dr. Schwarzbein. It's hard to ignore what you've been taught in med school. But everytime I read an analytical review of studies on saturated fats, there appear to be more studies that accidentally proved the benefits of saturated fats or a null effect than there are studies proving any harm.

Bottom line (and sorry for the round-about answer): Unless you have been low-carbing and can't get your cholesterol under 275, everyone should eat saturated fat. Saturated fat should not be avoided by the majority of people.