Okay, the following study and its results may sound strange, but it's damn intriguing.
Researchers at the University of Palermo recruited 23 people between the ages of 18 and 65 to eat a dozen green olives a day for 30 days. Amazingly, their average percentage of fat mass dropped by about 1.7% and their average muscle mass increased by about 1.39%.
To put in numbers that are more easily digested, the participants lost about a kilogram (2.2 pounds) and replaced it with roughly the same amount of muscle, without any changes in diet or exercise.
In science, results of this kind are often met with "huh?" and lots of head scratching.
The researchers, who were investigating a particular type of green olive known as Nocellara del Belice, tested the olive-popping participants for any probiotic effect, antioxidant effect, or anti-inflammatory effect.
While they couldn't find any definitive probiotic effect from eating the olives, they did find significant anti-inflammatory and antioxidant effects. Both interleukine-6 (IL-6), an inflammatory factor, and malondialdehyde (MDA), a free radical marker, decreased. Of course, you might expect to see similar effects from consistently eating any fruit or vegetable.
However, neither effect was strong enough to explain the dramatic swing in body comp.
The scientists think the results had to do with a particular fatty acid:
"The possible explanation could be linked to the capacity of conjugated linoleic acid (CLA) to reduce body fat levels. The molecule is present both in extra virgin olive oil and table olives, and can also be produced during their digestion."
Ever since its introduction to the supplement market in the mid 1990's (by yours truly, by the way), CLA has often shown promising fat burning and muscle building potential, particularly in animal studies. Human studies haven't always been as fruitful, but that may be for a number of reasons, perhaps most prominently differences in manufacturing standards.
However, a recent study in the American Journal of Clinical Nutrition found that individuals who used supplemental CLA experienced a monthly fat loss of about a pound a month. The results of the dozen-olives-a-day study, however, exceeded the fat-burning, muscle–building results from CLA seen in most studies.
Nocella del Belice olives are often marketed as Castelvetrano olives in the United States, whereas olive oil made from them is sold as "Valle del Belice" extra-virgin olive oil.
Alternately, and perhaps more effectively, you could take CLA directly. Biotest includes it in the Flameout® formula.
- Accardi G et al. Nutraceutical effects of table green olives: a pilot study with Nocellara del Belice olives. Immun Ageing. 2016 Apr 5;13:11. PubMed.