On a sweaty June afternoon up a flight of metal stairs in Bethnal Green, East London, a subculture is hard at work. A few dozen men (there are no women allowed here) grunt and groan as they repeatedly heave huge chunks of metal into the air, all in the pursuit of the perfect physique. Founded by former professional bodybuilder Savvas Kyriacou in the 80s, Muscleworks gym has produced several British champions.
Industrial fans, large enough to keep a plane in the air, stop taut, aching bodies from overheating. The hard work is all about image rather than fitness - tucked away in a corner downstairs, the gym's few cardio machines lie unused. The walls are lined with mirrors so the bodybuilders can admire their handiwork. Above those are hundreds of snaps of buff guys, including Kyriacou and Arnold Schwarzenegger back in his Pumping Iron days, flexing and posing. Inspiration for the determined congregation below.
But weight training is just one part of the bodybuilder lifestyle. At one end of the gym is a shop, stocked with all manner of substances to help its members pack on muscle. There are giant tubs of protein powder and smaller pots of less familiar products with names like Tribulus Terrestris and Branched Chain Amino Acids (BCAAs). Some of the branding is especially aggressive - Ripped Freak and Animal Nitro don't exactly sound like varieties of baby food.
Gym-goers have been taking 'supps' like these (and in some cases illegal steroids) for many decades, but over the last few years the market has bulked up massively.
Sales of sports nutrition products through mainstream retailers soared by 27% between 2013 and 2015, according to the research company Mintel. The total market size is estimated at £330m.
This surge in popularity has made a lot of cash for a group of successful entrepreneurs. Since the mid-noughties, we've seen several new British brands including Myprotein, Grenade and Bulk Powders go from nothing to turnovers in the tens of millions. All three featured in The Sunday Times Fast Track 100, an annual list of the nation's fastest-growing businesses.
One regular user of supplements is Jonathan Giannasi, a City lawyer who spends much of his free time honing his six-pack and competing in muscle model competitions. It may not be his day job, but keeping in shape requires strict discipline.
'I do count my macros - what protein, fats and carbs I have every day,' he says. 'I know what I'm having in every meal, how much calorie intake, but that's because it's become so ingrained into my lifestyle. If you took that away I would find it quite hard to cope and make normal food choices.' He hits the gym five times a week, and on those days consumes two protein shakes - one before and one after exercise. He also uses BCAAs, a specialised form of protein powder, carbohydrate powder and a pre-workout supplement to keep his energy levels up.
The lifestyle gets even more intense in the run-up to competitions. 'You're going to put 100 million per cent effort into making sure you're looking your best in 16 weeks, because the worst thing is to say I should or could have done this or that,' he says. 'The majority of the prep is restricting what you eat, there's no getting around that. If you're not willing to put that in then you're not going to be able to compete.'
People who take their training as seriously as Giannasi does are of course an important market for supplement manufacturers - and indeed he has managed to secure sponsorship from a few, including BioTechUSA. But the explosive growth thus far (and the real potential for future growth) has been down to the 'mainstream-isation' of supplements, and protein products in particular.
Once confined to health-food stores and the same dusty shelves in Boots as SlimFast's dreary meal replacements, protein powders, bars and shakes are now a common sight in Britain's biggest supermarkets. As of last July, 24% of consumers had used a sports nutrition product in the prior three months, according to the Mintel data, rising to a whopping 42% among adults under 25. It's not as if these products are cheap - a typical shake or bar will set you back more than £2, though powdered shakes tend to work out a lot less.
Grenade founders Alan and Juliet Barratt came up with their brand while working as nutritional consultants for the military. Their products come packed in eye-catching plastic grenades and ammunition crates, and have names like Black Ops, Thermo Detonator and.50 Calibre. 'We didn't want to stick it in a white tub and put it on the shelf with everything else, most of which you couldn't pronounce the name of,' says Alan Barratt. Launched in 2010, the brand turned over £17m in the UK last year, and was valued at £72m when private equity firm Lion Capital bought a majority stake back in March.
Barratt credits their growth partly to their decision to target consumers who wouldn't previously have taken an interest in sports products. 'We not only had an edgy brand that appealed to lots of people, but also we put products in locations, which everybody else thought were inconceivable. The supermarkets were one thing but we've gone over and above them ... we supply petrol stations and convenience stores.'
Grenade's snacks have proven particularly popular, a healthy alternative to carb-heavy crisps or chocolate bars. 'We sell tens of millions of units of drinks and bars per year, all over the world - we can't make them fast enough.'
Bulk Powders was originally a 'hardcore' brand, says its CEO and co-founder Adam Rossiter, but now it also pursues the 'larger segment of the market - the three to four times per week gym-goer, who isn't necessarily associated with any particular sport. Their goal is building muscle, losing fat and having an athletic physique.' Now the company employs 125 people and will turn over £35m this year.
Part of the market's growth is thanks to the increase in female consumers. Despite its macho branding, Barratt says that 49% of Grenade's customers are women. 'All our competitors just do it at half the size and make it pink. That's what you get if you have a corporate person developing a range. We don't patronise women, we make the best product and it works.'
There's also plenty of mileage in catering to alternative diets. Bulk Powders does glutenand lactose-free protein powders, as well as more natural 'paleo' protein made from beef, eggs and greens like spirulina. Upstart Neat Nutrition, founded by former GB swimmers Charlie Turner and Lee Forster, sells hipster-friendly vegan protein powder made from pea and hemp - it comes in the sort of brown paper bag you'd expect to find a batch of high-end coffee beans in.
The success of these specialist companies hasn't gone unnoticed in the wider food market. Now most FMCG companies are rushing to bring out their own high-protein products - or at least to emphasise the protein content of their existing range. Fancy a more protein-heavy start to your day but can't be bothered to whip up some eggs? Weetabix Protein contains more than 50% more of the good stuff than its normal variety. Earlier this year, Innocent Drinks launched two new smoothies, each packed with 8g of soya-based protein. Just last month Graze, the snack box subscription company, launched a new range of oat-based protein bites. 'This market is a key area for Graze and we're looking forward to innovating further in this space and seeing where we can go with the new line,' said its chief brand officer Sarah Fuller.
PACKED POWDER - WHAT'S IN A SUPPLEMENT?
The most popular type of protein powder, this is a by-product of cheese production. It's best consumed after a workout, when it is supposed to aid in the growth and repair of muscle tissue.
Another protein derived from milk, casein makes you feel full and takes longer to digest than whey, so it's often consumed before bed.
Branched chain amino acids - leucine, isoleucine and valine - are the most important elements of protein for muscle growth. But they may also play a part in the disease pathways of type 2 diabetes.
This helps bodybuilders and athletes exercise for longer and with greater intensity by boosting energy.
Another amino acid, this stimulates the production of carnosine, which acts as a buffer against muscle fatigue - that 'lactic acid' feeling when you exercise. Side-effects include paresthesia, a tingling sensation.
Is there a danger that the likes of Unilever and P&G could come along and eat Grenade's and Bulk Powders' (highprotein) lunch? 'I don't think so,' says Rossiter. 'Lucozade tried to do it and failed miserably. Huge brands can't just come along and take the core sports nutrition market just because they are a large brand.'
Barratt suggests Mars's decision to launch high-protein varieties of its Mars and Snickers bars has helped, not hindered Grenade. 'It's attracted so many more people to the market, and ours are a lot better ... people buy a Mars bar first if they're new to the category, but they don't buy another one - they come and buy one of ours.'
So why are high-protein products so en vogue nowadays? 'People are looking for a magic bullet,' suggests Graeme Close, professor of human physiology at Liverpool John Moores University and a nutrition consultant to England Rugby and Everton Football Club. 'Everybody wants to be fitter, healthier, people want cover model bodies - boys and girls - and we've been led to believe that's how it's achieved.'
But there are concerns that people are taking risks in pursuit of the perfect bod. Last month, Close told the BBC he thought the marketing of some products is 'wrong and immoral', and that some people were using them as meal 'substitutes instead of supplements' - something he strongly advises against. 'What we're talking about is just filtered milk - it's not something magical that's going to transform your body.'
In theory it's possible to achieve the same results just through eating a certain diet, but apparently it's all about convenience. 'If you can do it all through food, brilliant,' says Barratt. 'But most people can't because of the convenience. If I told you to eat six chicken breasts every day, you'd just be miserable.'
'You might finish a training session and it might be more convenient to grab a shake, but if you'd prefer to go and eat, then that's going to be better - it's certainly not going to be worse,' adds Close (after wolfing down a four-egg omelette for lunch).
You could be forgiven for wondering if we're in danger of eating too much protein, especially now it's available in such highly concentrated doses. But Close says he's seen little evidence excessive protein can have adverse effects on otherwise healthy people. That said, it could be bad for your wallet, as the body is only capable of synthesising so much protein at a time. 'What some people might do is have a big feed and wash it down with a protein shake,' he says. 'Now that is pointless - then you really are just creating expensive urine.'