The list of names in Lee Smith’s phone makes him look more like a celebrity agent than the boss of a multimillion-pound business aiming to break into the US.

He has got the numbers of reality TV stars from TOWIE, Made in Chelsea and Geordie Shore, each having got in shape using the supplements made by his company Forza at its factory in Ashford.

The brand is now sold in Boots, Tesco, Superdrug and many other retailers around the world, with deals to expand into Asda and Sainsbury’s expected to be signed this year.

From a turnover of £250,000 in its first six months in 2011, the company expects that mark to reach nearly £6 million this year, with plans to set up its first office on the other side of the Atlantic in 2015.

Mr Smith reveals he has just signed up ex-TOWIE beauty Maria Fowler and Made in Chelsea fitness fanatic Oliver Proudlock to endorse his products, which cost about £23 for a tub of 90 capsules.

“Aligning ourselves with celebrities has really helped but the stars we go for are ones people can relate to rather than A-listers,” said managing director Mr Smith, whose firm employs 24 people.

“Reality TV stars are more real. People aspire to be like them.”

Of course, earning the right to plaster Forza’s website with celebrity faces does not come cheap – and each star is not just looking to get paid.

“It is a two-edged sword with them,” said Mr Smith, 37, who lives in Mersham.

“They want to get something out of it beyond getting paid. They want to lose weight, get into shape or gain muscle.

“They want to work with companies which have got a high profile which can get them media attention as well.

“As long as we hit our targets and they hit theirs we are all happy. We are lucky because we have worked with a dozen or so celebrities now and we are known as good trainers.

“We get the odd one cancel the occasional workout session because of a heavy night but that is part of being in your early 20s, I guess.”

Despite the rapid expansion, business not all been plain sailing. The company suffered a blow to its image when a 24-year-old woman died last year after taking an overdose of its pills.

The amount of caffeine she induced was equivalent to more than 160 cans of Red Bull.

“It was a really sad situation,” said Mr Smith, who has two daughters – Marina, 11, who is at Ashford Girls School, and Adriana, aged 16 months.

“She had taken a full bottle of raspberry ketone, a bottle of wine and a packet of anti-depressants.

“She had been trying to commit suicide since she was 12.

“Unfortunately for her, and for us, when she decided to try a mode of getting there it was with one of our products.

“This was a really sad story of someone who was determined to take their life.

“It hasn’t affected our sales but it did affect us emotionally because we are really proud of why we set up this business and what it stands for.

“We couldn’t have stopped her taking 90 capsules but it goes against everything we believe in.”

Funding has also been an issue for the company.

When looking to build a factory, Mr Smith applied for a £500,000 loan from the Expansion East Kent fund run by Kent County Council but turned down an offer of £200,000 because it was too small and “they wanted too many guarantees”.

Its plans to expand into the US are also long overdue, having first been suggested in 2013.

Mr Smith was able to negotiate a credit facility from RBS to get his hands on cash while waiting for invoices to come through but has had to change banks to get hold of enough money for the US venture.

“I will probably end up setting up an office out there with a team of four or five people next year,” said Mr Smith, whose girlfriend Karen Page is the firm’s commercial director.

“Funding it is really difficult. A pharmacy chain in America will have 6,500 stores, whereas Boots in the UK has about 1,800.

“An order for one chain of $1.2m is quite expensive to produce.

“It might cost us £300,000 to make all that product.

“That value of order would be equivalent to four or five retailers over here in the UK.”

Mr Smith also said in 2013 he expected to expand staff to 200 in five years, which he still think is “very achievable”.

He added: “We are going to see some big expansion next year.”

Forza Supplements launched in Victoria, London, and moved to Javeline Business Park in Ashford in 2011, after Lee Smith took control of the firm from two business partners.

He set up the company after finding out his ex-wife was taking diet pills after having their daughter, which she had bought from a friend at the gym.

He said: “I was angry and said ‘if I can make you something that is healthier will you take it?’ I contacted a few manufacturers and was able to make something out of food and caffeine. The caffeine stimulated her heart rate while the food products quelled her appetite.”

He insists the product is “not a magic pill” and has to be taken with a good diet and exercise.

“These things make it easier for you,” he said. “They just give you more energy when you are cutting calories which is really important.”

He added: “Ultimately we all covet looking better than we do. You look in the mirror and you look at someone else and you want to look as good as they do.

“Rather than buying dodgy diet pills, now people can go into Superdrug and buy mine for £23 and know they are going to be safe.”