Words by Sue Quinn 

On a summer's morning in 1934, Laurie Lee waved goodbye to his mother in Gloucestershire and set off on an epic walk, heading first to London, then travelling south through scorching Spain. In his glorious account of that journey, As I Walked Out One Midsummer Morning, Lee notes that he took some cheese and a tin of treacle biscuits. During the Great Depression, this was all the food his mother could spare - but it turns out this was excellent fare for the road ahead. According to sports scientists, a mix of carbohydrate, fat and protein - all represented in Lee's rations - provides the energy your body needs on a long wander. 

Eat smart before you go 

What you eat prior to stepping out is just as important as the food you take with you, advises Jenaed Brodell, a registered dietician, sports scientist and founder of Nutrition & Co. 'Ideally, you want to combine a high-fibre carbohydrate with a protein and some healthy fats; she says. Consider tucking into a bowl of rolled oats, milk, yogurt and peanut butter for breakfast. Equally good is eggs on toast with avocado, or muesli with yogurt and mixed nuts. 

'A high-fibre carbohydrate will ensure glucose [sugar] levels in your blood are optimally balanced, so you don't get sugar crashes,' explains Jenaed. 'Adding protein ensures satiety [fullness], as do healthy fats.' 

Energise along the way 

Once you're walking, snack regularly to ensure your body has sufficient supplies of glycogen (the stored form of glucose). 'Every hour, top up nutrient stores with carbohydrates by snacking on granola bars, liquid carbohydrates such as juice or squash, fruit, yogurt or sandwiches, Jenaed suggests. 

Food and travel writer Caroline Eden, an ardent walker, also nibbles as she goes. She stuffs her pockets with snacks when striding the Pentlands and Scottish Highlands. 'I always carry Nairn's cheese oatcakes,' she says. 'I have a packet tucked into a pocket for eating on the move, because they stave off hunger well. A few Babybel cheeses are also handy.' 

Another food writer, Fliss Freeborn - known as 'the snack lassie' among her Scottish mountaineering pals - shares her top tip: 'Hard-boil some eggs and pop them in your pockets straight away to help warm you through, then eat them when they're cold.' (The shells take a long time to compost - as does orange peel and banana skin - so take them home.) 

It's a good idea to adjust your supplies to your circumstances, too. Jenaed explains that walking at altitude and/or in extreme temperatures (either hot or cold) requires more fuel than in normal conditions, because our energy requirements increase. We can also need more fuel as we age. 'As we get older, our metabolic rate usually slows down slightly,' explains Jenaed. 'However, our heart rate can remain at a high percentage of our maximum heart rate - and therefore we require more carbohydrates to keep us going.' 

Hearty bites for long hikes 

For hikes of more than three hours, Jenaed suggests packing something more substantial in a lunchbox. 'I recommend a nutrient-dense meal such as pasta salad with chicken and vegetables, or a bagel with sliced chicken and avocado.' 

Caroline, meanwhile, favours vegetable pasties and sandwiches: 'It needs to be food that won't fall apart or go soggy.'  

Fliss takes something nourishing but also delicious, so it motivates her to keep going until the next eating point. But some walkers might find her choices surprising. 'Leftover roast dinner in a zip-lock bag is a brilliant walking meal,' she says. 'You can pick at it when you want to, rather than ingesting a whole round of sandwiches and feeling like you need a nap after lunch.' And her favourite walking snack? Cold pizza. 'I cook it the night before, slice it and wrap it in tinfoil. It's got carbs, fat and protein, doesn't take up much space in your bag, plus it's nice and cheap. A winner all round.' 

Something different 

Fliss isn't the only walker who carries unusual snacks. Head chef Nina Matsunaga runs the Black Bull in Sedbergh, on the edge of the Lake District, with her partner James Ratcliffe. Both keen hikers, they're currently tackling the Lakeland Fells, chalking up 15 miles twice a week. 

Nina's walking food is inspired by the cuisine of Japan, where her parents were born. Sometimes the couple pack bento boxes filled with sushi components: precooked sushi rice, cucumber, avocado, smoked fish, ginger, cooked spinach, sauces, furikake seasoning, seaweed, sesame seeds and shiso leaf.  

For something warming, they turn leftovers into tanuki ramen, a flavourful noodle soup. 'It's the ultimate picnic food in Japan, and what everyone takes to work for lunch; says Nina For this, they pack two insulated flasks: a wide-necked one for the noodles, meat or vegetables, and another for the steaming hot broth. 'You just combine them when you want to eat; explains Nina. 'It might seem like a lot of fuss, but our days out are a real occasion for us, so we like to bring something nice to eat while we take in the solitude and the views. It also gives a healthy energy boost.' 

Sweet rewards 

Sugar is often demonised, but it's important when it comes to exercise performance and long hikes. 'We need the quick-release carbohydrates,' Jenaed explains. On longer walks, she recommends high-fibre granola bars, fruit with the skin on, spread with peanut butter or eaten with nuts, and energy balls made with oats. 'This will ensure a steadier release of glucose into the bloodstream.' 

Caroline is a fan of homemade energy balls. She blitzes cocoa powder, dates, peanut butter, nuts, seeds, prunes and honey or date molasses in a food processor, rolls this into balls, then chills them to help them set. 

Fliss also opts for homemade treats over expensive protein bars and gels (although she believes these are useful in case of emergency). Nut-studded flapjacks and brownies are her favourites. 'Both are dense and sustaining enough to work as a decent summit snack,' she says. 

Quick-release sugary snacks deserve a place in the backpack, too. 'They'll do wonders if you have a drastic energy dip; says Jenaed. Fliss's go-to for a fast-acting sugar hit on long walks or hill runs are Haribo Tangfastics. Ultimately, it's important to take food you love on a walk. 'It's all about satisfaction and satiety,' says Jenaed. 'As long as it's practical and enjoyable, it's a yes.' 

In his memoir, Laurie Lee says that his treacle biscuits 'tasted sweetly of the honeyed squalor of home', and almost made him turn back. I wonder what he would have made of a hot flask of ramen, or a roast dinner in a zip-lock bag?