When you hear the word “diet”, you probably picture a plate that’s free from fatty foods, because for the last few decades, we’ve been told that eating fat makes us fat.
We’ve been told that low-fat diets are good for lowering our cholesterol and reducing blood fat content, making them healthier for our hearts.
But this thinking is now being challenged.
A team of Israeli, German, and American researchers has just published a study in the Journal of Hepatology that looks at the effects of a particular high-fat diet.
You might know it by its common name, the Mediterranean diet, and you might have expected us to be warning you away from it because of its high fat content, but we’re not. We are recommending it despite that, because science has shown that it’s much heart-healthier than a low-fat diet, and for quite a surprising reason.
The researchers recruited 278 overweight people, and specifically folks who carried a lot of fat around their midsections. The scientists chose this group because they thought that carrying a spare tire might be the biggest risk factor for both cardiovascular disease and diabetes.
The subjects were put onto different diets for 18 months to see how each one measured up. They either followed a low-fat diet or a Mediterranean diet that featured low carbohydrates and 28 grams of walnuts per day. Both diets offered roughly the same number of calories.
The researchers used MRI scans to measure the different types of fat lurking inside the subject’s bodies, and they did this before, during, and after the 18-month dieting period. They also measured a wide variety of risk factors for diabetes and cardiovascular disease.
At various points during these 18 months, they asked the subjects to either do some moderate physical exercise or do no exercise at all to see what difference this would make, if any.
After the 18 months, the researchers found that their subject’s visceral fat (the stuff around the abdomen) had dropped by 25 percent, and their hepatic fat (around their livers) was even better at 29 percent. They measured a healthy 11 percent loss of fat around their hearts, and a one to two percent loss of both pancreatic and muscle fat.
But it’s worth remembering that these were just averages that concealed the most important findings: that those who exercised lost more weight of all kinds than those who did not, especially abdominal fat. No surprises there then, but the most interesting result they found was that losing liver fat was more important to health than losing stomach fat.
They came to this conclusion because they found that the people who lost the most hepatic fat were less likely to suffer from cardiovascular and metabolic diseases. They had lower cholesterol, lower glycated hemoglobin (a sign of insulin sensitivity), and healthier livers.
Which means that big bellies shouldn’t worry us as much as fat livers. Of course, it isn’t possible to know how much fat your liver is swathed in unless you happen to have an MRI scanner handy, but you can stay on the safe side by adopting the low-carb Mediterranean diet. Test subjects who did this were the ones who lost the most hepatic fat, which is why a Mediterranean diet is probably healthier than a standard low-fat diet.
Just to be clear, the folks on both diets lost almost the same amount of weight, but the Mediterranean dieters were clearly healthier when it came to their cardiovascular and metabolic risks.
This comes as a surprise when you consider that the Mediterranean diet already contained a fair amount of fat in the form of olive oil before the 28 grams of walnuts were added. They were eating quite a lot of fat, but this proves not only that it wasn’t doing them any harm, it was actually boosting their heart health.