Fat Part I: The Misunderstood Macronutrient

Which Diet is better at Reducing Cardiovascular Risk: Low-Carb or Low-Fat?

“Eating fat does not make you fat.” – The National Obesity Forum and Public Health Collaboration

“’Eat fat, cut the carbs, and avoid snacking to reverse obesity and type-2 diabetes’ report is irresponsible and misleads the public.” – Professor John Newton, chief knowledge officer at Public Health England

And we wonder why everyone is confused about diet and nutrition. The aforementioned is a health charity that calls for a return to whole foods, including high-fat sources like whole milk. Their position includes a claim that low-fat dieting creates “disastrous health consequences.” Is there any evidence? The science community, including Professor Newton, says no. But do they have proof that a lower-fat diet protects against heart disease and obesity? Let’s take a look.

Experts Connect High-Fat Diets to Heart Disease for the First Time

The first large-scale attempt to show that high-fat diets cause heart disease began more than 50 years ago with the Minnesota Coronary Experiment. High-fat diet supporters latched onto criticism of the study this year. Headlines across the world now scream we’ve been lied to! They claim the study lasted only one year and didn’t show any differences in cardiovascular incidents.

If researchers did attribute a difference in heart attacks during the one year study phase based on acute changes in diet, I think we’d have a problem. This is where bloggers should stick to blogging and let researchers do the researching. And interpreting.

Were Experts Wrong about Fat?

Digging deeper, both the trial and treatment group consumed the same amount of total fat (38 to 39 percent of total calories). This wasn’t a low-carb-versus-low-fat study, as current hype might make you think. The trial group consumed twice as much saturated fat (18 percent compared to 9 percent) and about 3 times the total cholesterol (446 mg versus 166 mg) compared to the treatment group. This was a supervised, inpatient study—research gold, thank you—including 10,000 participants. Though the study wasn’t long enough to compare heart disease incidents at the time, a year is an impressive amount of time to gauge heart disease risk factors. The average serum cholesterol level fell 15 percent in the lower-saturated fat dieters compared to 2 percent in the higher-saturated fat control group. That’s significant. But, the harsher reality is that the study did not compare either of these results to a low-fat diet. Almost 40 percent of calories from fat—saturated or not—is extremely high by any standard.

The Public Health Collaboration special-interest lobby claims that scientific organizations and proponents of low-fat/low-saturated fat diets have been corrupted by special interests of their own. The science community points out that the National Obesity Forum/Public Health Collaboration isn’t peer reviewed nor does it disclose funding sources. Politics knows no bounds. Controversy sells.

Looking Beyond One Study on High-Fat Diets

When looking at the amount written about this recent criticism of the Minnesota experiment, it seems the entire news industry has latched onto a conspiratorial claim based on the misinterpretation of a 50-year-old study that likely proves the opposite of their intent. No one is fact checking or comparing it to the entire body of cumulative research.

So, let’s look at a larger body of cumulative research. The American Journal of Epidemiology reported on a meta-analysis that included 23 international trials and almost 3,000 total subjects. Low-carb (less than 45 percent of calories from carbs) and low-fat (less than 30 percent of calories from fat) were found almost equal in terms of reducing metabolic risk factors. Findings were actually split, with low-fat diets reducing LDL and total cholesterol at slightly greater rates while low-carb diets were slightly more effective at increasing HDL cholesterol and lowering triglycerides. The individual studies were not described as supervised or inpatient. Perhaps a tie between the opposing diets, but a win for a simple reduction in food intake and body weight.

Clinical versus Real-World Research of Dieting Methods

Could the World Heart Federation be wrong when stating a diet low in saturated fat reduces risk of heart disease by 73 percent? They’re comparing to a typical Western diet, but there is value looking at exact, inpatient, clinical data as well as what people naturally gravitate toward. Both sets can be compelling.

For example, in a year-long study that compared a very-low-fat diet, a very-low-carb diet, and two more moderate diets, both the low-carb and low-fat diets resulted in the worst compliance.

Cardiovascular Risk Improvement…a Tie?

I discussed in my series on carbohydrates that low-carb and low-fat diets seem to trade wins and losses from study to study, but when food intake is strictly controlled by researchers, low-fat diets are more effective for weight loss and health status. Research also clearly shows that any method of losing weight is an improvement, but there are unique differences with each method. Recall the aforementioned study that showed low-carb diets might best low-fat diets in HDL elevation and total triglyceride levels compared to the low-fat diet advantage in reducing LDL. One particular study repeated this outcome with no difference in total weight-loss success after one year. Perhaps designer diets for different goals might be on the horizon?

Low-carb and low-fat diets are both effective at reducing weight and cardiovascular disease risk factors. Compliance is the driving success factor. Which is easier for you to follow? Is dietary fat, or certain sources of fat, necessary for health? We’ll find out next time!

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