Nature's Most Extreme Fat Loss Crash Diet

Humpback whales undertake nature's most extreme crash diet, shedding around a third of their mass in less than two months but, happily, without any negative health impacts.

Researchers from Australia's Griffith University used drones to follow 103 adult humpback whales on their 5,000 mile (8,000km) journey across the southern hemisphere, from their cold-water feeding grounds on the Western Antarctic Peninsula to the warmer climes of their breeding site off the coast of Colombia. They discovered that the whales burn through blubber equivalent to the mass of two adult African elephants - that's a whopping 24,250 lb (11,000 kg) - reducing their bulk by more than a third. And, along the way, they consume no food at all. Not even a snack.

To power this epic journey before setting off, each whale needs an estimated 28.5 million individual krill - an amount that's heavier than an Airbus A320 jet.

This extreme fat loss provides new insights into the animal's robust physiology and metabolism - and how much fuel is needed to complete this 6 to 8 week migration. According to lead researcher Alexandre Bernier-Graveline, the energy they burn is roughly equivalent to all the calories that an average human consumes in 62 years.

Unlike humans, whale blubber is a more readily available fuel to burn than what we store in our fat cells. As such, their extreme fasting regimen doesn't impact their overall health or damage organ systems. It also explains why female humpbacks remained healthy enough by the time they reached the tropics to birth calves.

This new research - published in the journal Marine Mammal Science - will help scientists better understand the needs of humpbacks and how the availability of keystone species krill could directly impact whale numbers. "By linking migration and reproductive energy costs to krill biomass, our findings provide critical ecological context for understanding how environmental changes such as krill population fluctuations could impact whale populations," the researchers noted.

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