For the past 50 years the basis of nutritional advice from the medical community has been “eat a low-fat diet”. During that time the obesity epidemic, the diabetes epidemic and growing concerns about a shortening in U.S. life expectancies has occurred. In addition, an increase in cardiovascular disease rates has occurred in 34-54 aged women and no further decrease in the rates for middle aged men.(1)
At some point it is prudent to say that if the desired effect of a policy is not occurring, the policy must be flawed. This is the case with the low-fat diet. The results have proven this concept highly flawed at great expense to our national health.
The idea of a low-fat diet as protection against cardiovascular and other chronic disease originated in the 1950’s based on some seriously flawed research by Ancel Keys, PhD. He examined the carbohydrate and fat ratios in relation to cardiovascular disease rates from “all of the research” published world wide up to that time. The infamous Seven Countries Study concluded that the analysis from the seven countries reported that higher fat consumption correlated with higher cardiovascular disease rates and began the unquestioned era of the low-fat diet as disease prevention.
Unfortunately, Key’s study did not come under independent analysis for the next 50 years. When it did, it was revealed that he had “cherry picked” the available research including only 7 of the 22, or less than 33%, of the available studies. Examination of Key’s data 50 years later found that the majority (66%) of the research he actually had available supported exactly the opposite of his conclusion. Keys was opening a health spa/retreat which was to be based on the low-fat diet and biased his study to support its concept.
Several studies throughout the late 1900s and early 2000s actually demonstrated that the low carbohydrate/higher healthy fat diet actually out-performed the low-fat diet, but these studies failed to change longstanding medical advice patterns. It however, has begun to soften very recently and perhaps a large, well done newer study will finally change this flawed advice.(2)
The study called PURE examined the relationship between dietary patterns and disease and mortality rates from 18 countries from 2003- 2013. Subjects were divided in to groups, according to the carbohydrate/fat ratios of their diets. The data showed that compared to those consuming the lowest carbohydrate/higher fat diets, each increase level of higher carbohydrate and lower fat consumption was associated with higher cardiovascular disease rates and increased total mortality rates. Compared to those consuming the lowest carbohydrate, those in the highest quintile had a striking 30.8 % increased risk of cardiovascular disease and a 75.6 % increased risk of total mortality.
The conclusions of the authors of this new study tell the whole story; “In conclusion, we found that a high carbohydrate intake was associated with an adverse impact on total mortality, whereas fats including saturated and unsaturated fatty acids were associated with lower risk of total mortality and stroke.”
“Low-fat” had to result in “high carbohydrate”. Humans had historically consumed only about 35-40% of their energy from carbohydrate. In the last 100 years this has ballooned to 55-60%, an almost doubling while our metabolic “wiring” has not changed. We have been trying to consume a diet that is incompatible with our physiology and the results been unfortunate. Change needs to occur.
Our blind faith that medical advances can outstrip the negative effects of human dietary behavior is proving wrong. Unquestionably, medical therapy does help delay the adverse effects of poor diet, but it does not prevent the eventual outcome. Good medical care can push back the complications of diabetes and overweight/obesity. This is tempered by the fact that the average age of onset of many diseases such as diabetes have plunged. While diabetes treatment may push back the development of complications of the disease by 15 years, the age of onset has dropped 16 years since 1970. That math affects mortality plain and simple.
The authors final conclusion says it all: “Global dietary guidelines should be reconsidered in light of the consistency of findings from the present study, with the conclusions from meta-analyses of other observational studies and the results of recent randomised controlled trials.” Low-fat/high carb was a grand experiment whose unfortunate outcome has cost a high price. Time to put the final nail in and move on.
- Ford, E. S. et al. Coronary Heart Disease Mortality Among Young Adults in the U.S. From 1980 Through 2002: Concealed Leveling of Mortality Rates .J Am Coll Cardiol 2007;50:2128-2132.
- Deghan et al. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. Lancet, 2017; 390: 2050–62.