Hello all, this week’s blog post is coming from my husband, Dave. (He was complaining about being stuck in the shipping department, so I figured I would let him have a turn at doing a blog post.)
With the onset of World War II, the rates of heart disease in America suddenly dropped. Then, when the war was over, the rate of heart disease immediately jumped back up again. Doctors and nutritional scientists searched hard to try and understand what was causing this. Epidemiologists also noted that during the war years meat, eggs and dairy products were strictly rationed, and thus wondered if the reduced consumption of these foods might be a factor.
In the 1960’s a possible explanation, called the “lipid hypothesis” emerged. Basically, the lipid hypothesis is as follows:
a) Cholesterol and/or animal fat in the diet is associated with cholesterol in the blood;
b) Cholesterol in the blood is associated with plaque formation in the arteries and, consequently, heart disease;
c) Cholesterol and/or animal fat in the diet causes heart disease.
At the time the lipid hypothesis was proposed, there was very little data available to support it, but it seemed to make intuitive sense, and it offered a plausible explanation for why rates of heart disease had decreased during the war.
In July of 1976 senator George McGovern, who chaired the Senate Select Committee on Nutrition and Human Needs, called a hearing to investigate the links between diet and heart disease. Based on testimony provided by a variety of “experts”, the committee issued a set of dietary guidelines calling for Americans to reduce their consumption of saturated fats from sources such as red meat and dairy products. Though the beef and dairy associations were not very happy with this, the promulgation of these guidelines helped the lipid hypothesis to become widely accepted as established fact and the American diet underwent a massive shift toward low-fat food choices.
This was a huge financial boon to the processed food industry, which rushed many new products into the market, each proudly proclaiming its low fat content. To achieve a reduction in saturated fats, processors switched to vegetable-based fats (including trans fats), and also substituted sugar and other carbohydrates.
Butter, lard, whole milk and red meats all found themselves on the “bad” list, while margarine, vegetable shortening (e.g. Crisco), 2% or non-fat milk and lean poultry joined processed foods like Snackwell’s low-fat cookies, Lean Cuisine dinners and diet soda on the “good” list.
Those born in the 1970’s or later have been taught all their lives that low-fat foods are supposedly healthier, and as a nation we all have been consuming these low-fat alternatives for decades. The only trouble is that eating this way has made us even fatter – and much sicker.
So what’s going on? Well, it turns out the science behind the lipid hypotheses never was very sound, but due to extremely strong political and financial support, very few were willing to challenge the accepted dogma. And now, after decades of collecting experimental data (where we all played the role of low-fat diet guinea pigs), it is becoming quite clear that the lipid hypothesis is just plain wrong. Articles and papers that debunk the lipid hypothesis are showing up with increasing frequency, often from the same organizations that advocated for the lipid hypothesis in the first place. Oops. But alas, such is often the way with science, and especially so with nutritional science.
But what about that drop in heart disease rates during World War II? If the lipid hypothesis is bogus, what caused this? While we don’t know for sure, it could easily have been due to many other factors. During the war, gas and sugar were also both strictly rationed, and as a result, people ate a lot less sugar (along with less meat and dairy). They also ate more plant foods (because they were not rationed and were in greater abundance), and they walked a lot more. Maybe the combination of a healthier diet and more exercise (which is what we hear a lot about today) actually works to reduce the incidence of heart disease.
So if low-fat foods are not so good, what are we supposed to eat? Does this mean we should go for the Double Stuff Oreos instead of the reduced fat cookies? Should we have beef every night? Should we switch from diet soda back to regular soda?
Stay tuned for next week’s blog post where I will describe where the lipid hypothesis went wrong and will also offer suggestions on how we should be eating in the post lipid hypothesis era.
In the mean time, leave some comments about your own experiences. Has a low-fat diet helped you to become trimmer and healthier?