We pitiful humans agonize over the cellulite on our thighs, bewail our rippled buttocks and abhor our adipose-afflicted abdomens – but the true enemy is within. Visceral adipose tissue, fat that accumulates around our internal organs, poses a greater danger than any sneers we risk from revealing our external lard in tank tops.
Now researchers at Ben-Gurion University of the Negev, Be’er Sheva, report that a “Green Mediterranean diet” high in polyphenols and fiber can reduce that visceral fat, even more than living on a normal “Mediterranean diet” or the “healthy diet” as recommended by authorities. The paper appeared Monday in BMC Medicine.
Pitting the Green Mediterranean diet against the Mediterranean diet and a healthy diet in an 18-month clinical interventional trial reduced visceral fat in all cases, the researchers report. But the Green Mediterranean was twice as effective at battling the inner bulge as the Mediterranean Diet, which was better than the Healthy Diet.
After 18 months, those subjected to the Green Mediterranean diet saw a visceral fat reduction of 14 percent; eaters of the Mediterranean Diet saw a 7 percent drop. Visceral fat among “healthy eaters” was reduced by 4.5 percent. All the test subjects experienced weight loss, to about the same degree. The key issue was reducing the visceral fat, by a significant degree, the researchers explain.
The impact of the diets, maintained over 18 months, was measured by MRI scanning the 294 test subjects before and after the 18-month dietary intervention.
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By the way, all three groups were exercising: There was no control group that stayed couch-bound, according to the researchers. The study was led by Prof. Iris Shai of Ben-Gurion University and doctoral student Dr. Hila Zelicha with an international team.
Enter the duckweed
The Mediterranean diet is not actually a single defined thing, but it has principles: heavy on vegetables, legumes, grains, nuts and fish; poultry and dairy are “okay”; and very sparing in consumption of carbohydrates and red meat, Shai explains. In the Mediterranean diet strategy, calories from bread, potatoes and pasta are “empty,” especially if we want to reduce our fat.
The Green Mediterranean diet concocted by the researchers involves practically no red meat and is relatively high in fiber. It boils down to the Mediterranean diet plus 28 grams of walnuts a day, three to four cups of green tea and 100 grams (measured in the form of frozen cubes) of duckweed shake.
Duckweed? It is a water plant, aka water lentils. It is rich in protein that our bodies can digest, as well as iron, B12 and other vitamins, minerals and polyphenols. Duckweeds thrive in swampy environments. They are weird little plants with no proper stems or leaves; they look like they have proper stems and leaves, but they don’t. After baffling botanists for decades, they are now considered to belong to the greater family of weird plants called monocotyledonous flowering plants, which go back to the Cretaceous.
In other words, the Green Mediterranean diet is the Mediterranean diet with walnuts and duckweed to add protein, and lots of green tea to add yet more polyphenols – the duckweed is also rich in that class of chemicals too.
Nutritionists extol the virtues of polyphenols because of their antioxidant activity, which some research suggests may help reduce the probability of developing certain cancers and chronic diseases.
The upshot of the Green Mediterranean diet is to double the consumption of polyphenols through the green tea and duckweed shake: they reduced red meat and added to the plant sources, explains Shai, a professor of nutrition and epidemiology.
The Mediterranean type of diet is high on polyphenols, if one does it right, which benefit adiposity by several mechanisms, the team explains; the Green Mediterranean diet is just even better.
There are caveats. The sample size was just 294 people, the test period 18 months. Also, we cannot know at this point how eating the Green Mediterranean diet over more time would affect the body. We can know this, Shai says: Previous work has shown that the Green Mediterranean diet has a profound impact on the microbiome, our internal population of microorganisms that, among other things, do a lot of digestion for us. To be accessible to us, for instance, polyphenols must first pass through our friends the gut microbes.
What damage does visceral fat do, anyway? “Visceral fat aggregates over time between organs and produces hormones and poisons linked to heart disease, diabetes, dementia and premature death,” the Ben-Gurion University article explains.
“A 14 percent reduction in visceral fat is a dramatic achievement for making simple changes to your diet and lifestyle,” commented co-author Zelicha, though obtaining a daily duckweed shake may not be so easy. But the results, the team finds, may be impressive.