How Bad Science gave Saturated Fat a Bad Name
Part 2: It’s about the carbs, Dummy!
Vetting and weeding out the vast amount of literature reporting on poorly designed health and nutrition studies is a thankless challenging task. Some of these research projects receive millions of dollars to investigate topics and to publish conclusions that no informed person would dispute. There’s no better example of wasted resources than on the research that has been undertaken to determine whether we should be eating more or less saturated fat.
What’s the Randle Cycle?
In 1963 a scientist by the name Philip Randle described a process showing the adverse metabolic consequences of carbohydrates and fats competing for substrates. What was dubbed the “Randle Cycle” states, in highly oversimplified terms, that if we consume carbs and fat in the same diet, we’re going to get fat and we’re more likely to be battling diabetes in the future.
Although the biological mechanism that drives the negative implications of mixing carbs and fats is subject to some dispute, the phenomenon itself is widely accepted. Many popular diet plans, such as Trim Healthy Mama, are based on the concept that you can eat either carbs or fat, but you can’t eat them both at the same time.
Unfortunately, the majority of nutrition research scientists skipped class the day the professor discussed the Randle Cycle and as a result they design studies that prove nothing other than what Randle already showed us decades ago.
When you see conflicting conclusions in research, more often than not, this is the major flaw in the study, or at least in its stated conclusion. They fail to give credit to the proposition that the underlying diet, not the intervening variable, is the culprit causing the problem.
Case in point. Too much rice in China.
In 2017, some Chinese researchers decided to test the proposition that reducing carbohydrates in favor of more fat would lead to reduced weight loss, the general proposition behind a low-carb diet. They noted the paradox that between 1982 and 2011 the Chinese population had reduced carbohydrate intake from an average of 72% of dietary intake to 54%, yet the Chinese population had rapidly seen the rate of obesity increase far beyond what had occurred in the Western world during the same period.
So they designed a controlled trial that compared three diets. Carbohydrates in the three diets represented 66%, 55% and 46% of dietary caloric intake. The fat intake in those diets was about 20%, 30% and 40% respectively. Fiber and protein remained constant in the three diets. The results, which the researchers described as somewhat paradoxical, are exactly what I would have expected. With a comparison of three diets so heavy in carbohydrate composition you should fully expect, based on the Randle Cycle, that the diet with more fat was going to lead to more negative results.
Neal Barnard’s Poorly Designed Study on Saturated Fat
When you’re looking for a poorly designed study, one that’s designed to push an agenda rather than to provide some new insight into nutrition, where better to look than something done by vegan diet proponent Neal Barnard?
My criticism of Barnard should not be taken as condemning a vegan diet. Anyone who has read my articles knows that I take the position that green leafy vegetables and cruciferous vegetables should be at the foundation of any healthy diet. What I loathe is that Barnard constantly makes near-ridiculous claims about the dangers of non-plant-based foods and then attempts to support them with his biased, self-serving propaganda disguised as legitimate research.
In a study reported in a paper published in 2019, a group of researchers working with Barnard, conducted a study that demonized saturated fat, including the omega-3 fatty acids that have been indisputably associated with health benefits, or at least I thought so before reading this paper.
This study randomly assigned subjects to two groups. The control group continued to consume 46% of their diet as carbohydrates and about 35% from fats. The intervention group, also consuming a high-carb diet, reduced their fat intake by about 50%. No surprise, all Neal’s poorly designed study told us is what Randle showed us 60 years ago, that if you eat a lot of carbs, you should limit the fat.
This design flaw of blaming fat for the problems caused by the underlying diet isn’t something only Barnard and those Chinese researchers have done. It’s the central reason there are so many scientific studies that purport to have found that fat is unhealthy.
You see where this is going, right? If you design a study where the underlying diet doesn’t have an inordinate abundance of carbs and add more fat and saturated fat to that lower-carbohydrate diet, you don’t see the negative outcomes.
With lower dietary carbs, higher fat and protein are irrelevant
A good example is the study designed by Ronald Krauss, Sally Chiu, and a group of scientists studying the effects of diet on 158 obese adults from a population of patients at San Francisco General Hospital and the Cholesterol Research Center in Berkley, California. The study, published in 2014, sought to assess, like Barnard’s study, the impact of increasing fat in a diet.
The adults in this study were divided into four groups. All groups were placed on a diet that was 35% carbs, 10 percentage points less than the control group in Barnard’s study. The diet in each group was designed to show the effect of increasing both protein and/or fat while consuming 35% of caloric intake as carbohydrates. Their findings indicated that when the underlying diet was reduced to 35% carbs, increasing total fat from 30% at baseline to 45%, and increasing saturated fat from 7% at baseline to 15% yielded no significant increase in biomarkers associated with either cardiovascular disease or diabetes.
The takeaway
In all three studies, the stated conclusion was technically correct, but the researchers masked the truth in their conclusions.
The real finding in the Chinese study is that because the Chinese population is going to consume a high-carbohydrate rice-heavy diet, that population will have to limit fat in their diet. More simply stated, if you mostly eat rice, you can’t eat pork belly.
The real finding in Barnard’s study wasn’t that we should all eat vegan, which is how he portrayed it, it was that if you’re eating a diet high in sugary soft drinks, pancakes, and pizza, you probably shouldn’t eat bacon for breakfast.
The Krauss research group concluded that higher fat and protein with a diet limited to 35% carbohydrates wasn’t a bad thing. In other words, skip the sugary soft drink and the Big Mac and you can probably eat several slices of bacon with those pancakes without causing too much damage.
In the final analysis, these studies weren’t about fat at all. The real message was, “It’s about the carbs, Dummy!”
