The joy of insects: why bugs are an athlete's best friend

'I pick the wings off them, because you wouldn't want those parts. Then I dry-roast them and mix them with dates, nuts and cocoa in the food processor. Delicious."

Welcome to the world of Marcus Leach, adventure athlete, writer and cooker of insects - specifically crickets, a protein source that has played a big role in creating the lean physique that sits before me today.

The former rugby player set about transforming his body in 2013, dropping from 24 per cent body fat to nine per cent via a stringent 11-month programme that saw him consume up to six portions of protein every day to help his muscles recover after gym sessions. Wary of red meat's hormone content, Leach turned to insects - a food he first tried while travelling through Zambia.

Today, the 33-year-old has become an unofficial arthropod ambassador, championing six-legged critters as the ultimate health snack and go-to midweek supper ingredient. He often cooks "spicy grasshopper bean sprouts" and adds buffalo worms to his carbonara - "you get a really nice mushroomy flavour".

For Leach, bugs aren't just a tasty treat, they are a pure fuel source. In May, he will embark on a 10,000km cycling odyssey, riding the Tour de France, Giro d'Italia and Vuelta a España routes back-to-back. "I won't be able to whip up a stir-fry when I'm in the saddle," he says, "but I'll have my cricket energy bars."

Leach is part of a new contingent of fitness fanatics who are using insects to support their lifestyles. "Insects are the original superfood," says Neil Whippey, co-founder of Grub, an entomophagy start-up. "Human civilisation has eaten insects for thousands of years, it's just modern agriculture that's led us to think of them more as pests."

Four years ago, Whippey opened a pop-up restaurant in Hoxton with the aim of educating foodies about the nutritional and ethical benefits of eating crickets.

Not only are they nutritionally dense - "69 per cent protein, and iron and calcium rich," says Whippey - but they're also "metabolically efficient". This means they convert much of the food they eat into body mass, ready to be passed up the food chain. To put that into numbers, crickets require six times less feed than cattle to produce the same amount of protein per gram, according to a report by the Food and Agriculture Organisation of the UN.

"It's not just crickets' protein profile that makes them attractive," says clinical nutritionist Jamie Richards, pointing to a ratio of omega 3 to omega 6 fats that is similar to oily fish, like salmon.

These fats have been proven to boost HDL cholesterol - "good cholesterol" - and to reduce risk factors associated with heart disease. And then there's the iron content. For every 100g of raw crickets, the body receives a healthy 10 milligram shot of iron - an essential component for any endurance athlete.

Richards now dissuades athletes from using high-sugar energy gels for refuelling while on the go. Instead, he advocates wasps, grasshoppers, crickets and mealworms as a means of replenishing lost nutrients during and post-workout.

But what about the taste? Having tried Grub's energy bars, I can confirm you won't find yourself dislodging wings from your molars or glugging Listerine to flush out the flavour. They're not as instantly delicious as the glycogen-rich energy gels you may have had, but they are pleasantly chewy, with what Leach terms "a subtle nutty flavour".

Why, then, has it taken so long for insects to trickle down to the mainstream. One big obstacle is the cost of importing them - hence why Grub is currently establishing the UK's first cricket farm in Cumbria, with a view to making an insect-based protein powder.

Leach expects it will be a while before insects become a staple health food. "It might not happen in my lifetime, but you never know the direction the world's going," he says.