How often do you eat a steak, an omelet, or cook with real butter? What kind of milk is in your refrigerator?
While animal protein arguably tastes good and makes us feel satiated, the nutrition community has steadfastly steered Americans away from eating red meat and whole fat dairy for the past four decades. The diet-heart hypothesis (coined by a biologist named Ancel Keys in the early 1960’s) proclaimed that a low fat and high carbohydrate diet provided the basis for good health. Although not proved through clinical trials, the hypothesis gained support from the federal government and provided the basis for mainstream dietary advice during the ensuing decades.
In my lifetime, the culture of the American diet has shifted dramatically. According to USDA, the consumption of grains (41%), vegetables (23%) and fruits (13%) rose significantly from 1970-2005 while red meat (-22%), milk (-33%) and eggs (-17%) fell dramatically. Overall carbohydrate intake for Americans rose with low fat starches, and vegetable oil took the place of animal protein and fat in the diet. Animal protein lovers shifted from beef to chicken, and many traded whole fat dairy for skim milk and margarine thereby forsaking nutrition density for lower saturated fat options.
All of this occurred during a time in the United States when obesity rates more than doubled (15-32%), the prevalence of heart failure, cancer and stroke all increased, and the rate of diabetes increased from less than 1% to 11%.
An association hypothesis (mirroring the process used by Ancel Keys to develop the diet-heart low fat mindset) might suggest from these two sets of data that replacing animal protein with vegetable oil and carbohydrates actually reduced the quality of health of Americans – the direct opposite from the intended consequence of Keys’ hypothesis. Uncovering this discrepancy inspired Nina Teicholz, an investigative food reporter, to delve deep into the nutrition archives. After nine years of research covering thousands of studies and a wide array of interviews with nutrition scientists, Teicholz uncovered a laundry list of interesting findings in her New York Times Bestseller The Big Fat Surprise.
- The current U.S Dietary Guidelines are based on Keys’ hypothesis and drawn from epidemiological studies primarily done on middle-aged men. Clinical trials have not confirmed the epidemiological data, and virtually no data exits supporting this hypothesis for women and children.
- The causal associations seen between red meat consumption and heart disease are minimal.
- The saturated fat found in animal protein increases HDL cholesterol (good cholesterol) which appears to play a positive role in heart health. Additionally, fat plays an important role in providing energy as well as ensuring that a number of essential vitamins be fully absorbed by the body.
- Total cholesterol is not a good predictor of heart disease for most people. In particular, LDL (bad) cholesterol does not consistently predict an increased risk of heart disease. The cholesterol argument is the primary basis for the advice to reduce red meat consumption.
- No health studies exist to discern the effect on health of liquid vegetable oils; and studies have shown that the process of solidifying vegetable oils (to make butter imitations) creates trans-fat which are incredibly unhealthy. Vegetable oil use is up 8% since the diet-heart hypothesis began to drive dietary advice.
- Carbohydrates are a primary cause of insulin secretion – the constant consumption of carbohydrates throughout the day creates elevated insulin levels in the bloodstream which renders the body unable to digest its fat stores. This leads to metabolic disorders such as obesity and diabetes. Eating fat and protein do not cause insulin secretion during digestion. High fat, low carbohydrate diets like the Atkins diet are more effective for achieving lasting weight loss.
- Multiple clinical trials demonstrate that a diet which trades carbohydrates for protein and fat can be healthy suggesting that a shift in thought process and nutrition study focus is prudent.
I encourage each of you to read Teicholz’s book. It is an eye opening experience that inspires the reader to guiltlessly enjoy a steak while thinking that perhaps it’s time to stop apologizing for fat…