Scientists say that an obesity is a necessary part of life for a brown bear, and these animals are doing just fine. The bears have their own diet depending on the season. In summer, the microbiota favours fat accumulation, and in winter it favours fat burning, gut bacteria keeps bears healthily obese, tells the article in the journal Cell Reports.
For brown bears, obesity is a must to be healthy, say the researchers from the Scandinavian Brown Bear Research Project. Samples from the bear faeces show a less diverse microbiota in winter when the animal traditionally sleep. The blood work also shows increases in the various forms of fatty acids and cholesterol, which makes sense as the bear will need to survive on its fatty insulation throughout at least half-a-year-long winter, says Frederik Bäckhed from the University of Copenhagen, Denmark.
To understand the role changing bacterial flora plays in the bear’s survival from summer to winter, the scientists feed the bear bacteria to sterile mice.
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Brown bears’ faeces gut became a subject of the research, the lab mice contain no inherent bacteria of their own. They are an expensive tool, as they are raised in a completely sterile environment in airtight chambers, and are birthed by C-section instead of natural birth. But it’s worth it as they are brilliant controls.
The mice that were fed summer bacteria became more rounded than mice fed winter bacteria, but the differences were not particularly striking. More interestingly though, mice fed summer bacteria showed no sign of developing insulin resistance. This confirms previous studies that showed that bears show no signs of metabolic mismatches in summer.
So the bear’s summer bacteria, seem to allow both the bears and the laboratory mice to accumulate fat without the negative side effects.