As Insider's Senior fitness and nutrition reporter, I was invited to check out The Body Lab and its facilities.The Body Lab offers a gym, as well as cutting-edge treatments, including hyperbaric oxygen therapy, cryotherapy, and a float tank.Membership costs £4,950 ($6,800) to £16,000 ($21,800) a year, and the top tier memberships include unlimited use of the facilities (including personal training sessions), one nutritional consultation per month, and a quarterly biomarker analysis.I was offered still or sparkling water when I entered (which I later learned were available for clients from taps throughout the building). My coat was taken and hung up, and I took a seat on the plush sofa.There was a fridge containing bottles of Fiji Water and some shelves offering a small selection of products for sale including workout clothes, Theragun massagers, and foam rollers.Nick Jacobs, The Body Lab's head of sales, told me their beans are roasted in Colombia on Friday to arrive by Monday morning. It was a very good coffee, but I was surprised that it was served in a paper cup (alongside my water in a plastic cup).There weren't any food or snacks available either, although they do serve protein shakes. Jacobs told me The Body Lab is all about data, education, and optimization, striving to offer everything busy people need for peak health under one roof.Kensington will be their flagship site, but the plan is to expand with more sites in London as well as Dubai and Singapore.The dots represent their three pillars: nutrition, personal training, and recovery therapies.Hyperbaric oxygen therapy is done in a compression chamber and is often used by pilots, astronauts, and deep-sea divers.It claims to provide an increase in oxygen and hydrogen to the cells via atmospheric pressure.Although there hasn't been a huge amount of research yet on this kind of therapy, a small study by Tel Aviv University found that it could reduce some biological signs of aging, as Insider's Gabby Landsverk reported.The Body Lab encourages its clients to have the therapy for a range of supposed health benefits, including increased energy and stamina, optimized cellular health, better wound healing, improved cognitive function, and pain relief.After climbing (rather ungracefully) into the chamber and lying down, Jacobs locked me in and stayed with me for three minutes as oxygen was slowly pumped in to increase the air pressure three times more than normal.It felt like going up in a plane, and I felt the need to yawn to unpop my ears. Once it stopped increasing though, the air felt normal.I took my laptop and phone (and some water) inside with me and attempted a bit of work, but it's quite hard while lying down.Jacobs encouraged me to relax into it and rest, and he came back to check on me a couple of times before gradually decreasing the pressure again at the end and letting me out. Jacobs told me some people step out and immediately feel like they've had 10 coffees. But for others, it's more of a gradual sustaining of good energy levels.Cryotherapy drastically reduces body temperature and the Body Lab says the treatment is designed to decrease inflammation, boost the immune system, blood circulation and metabolism, and aid recovery.The Body Lab's main chamber is set at -110°C (-166°F), which you enter after 30 seconds in an initial -60°C (-76°F) chamber, to not shock the body.Emerging research supports that it can reduce pain and encourage healing, but a small 2016 study found people did not experience body composition changes after 10 sessions.Jacobs also gave me a face mask, not for Covid, but because it's actually easier to breathe in the cold through one.The aim, he said, is to drop body temperature by 10°C (50°F) — before going in, mine was 33.9°C (93°F).The leaner you are, the quicker your temperature will drop, Jacobs said, so people with more body fat need to stay in the chamber longer to get the same results. Most people aim for three minutes in the coldest chamber, but the Body Lab encourages people to build up to that, starting with shorter sessions. He suggested I do 30 seconds in the first chamber and try for 90 in the second.Jacobs told me that if at any point I just wanted to get out, I could. It was helpful seeing both him and the countdown clock through the glass.As Jacobs had advised, I resisted the urge to tense my whole body and tried to relax into it.Needless to say, the underfloor heating felt great when I stepped out.My temperature had dropped 16°C to 17.9°C, which, Jacobs told me, was a lot. I felt good though: energized, but also with a sense of achievement for sticking out something uncomfortable. A float tank is exactly what it sounds like: The tank contains half a ton of Epsom salts in 35°C (95°F) water, which feels silky and allows people to float.You wear earbuds and are in complete darkness, the idea being that when your body is free from gravity, temperature, touch, sight, and sound, you can achieve an ultra-deep state of relaxation.The aim, Jacobs told me, is to fall asleep or at least enter a nap-like state.It was quiet when I was there mid-morning — I only saw a couple of members — but the Body Lab has only just opened, and Jacobs said they only have capacity for 250 anyway.Despite being a fitness reporter who is always visiting different gyms, I'd never used equipment that allows someone to change the resistance in different parts of a movement.For example, you can specify whether you want a bicep curl to feel hardest at the bottom, middle, or top, and strengthen different parts of the arm accordingly.It's slightly uncomfortable, but Jacobs told me you're meant to look directly at the light and expose your skin to it to get the purported benefits: boosting your mood and warming up the body.There is some research, such as this 2018 study, which suggests red light can have antidepressant properties.While there are Dyson hair-dryers available, I was actually surprised not to see more provided — most luxury gym changing rooms these days contain hair ties, sanitary towels and tampons, sometimes razors, and more toiletries, like body moisturizer or deodorants.Jacobs told me they're made by a man in nearby Belgravia who creates hazelnut oil using the nuts from his family hazelnut farm in Turkey.It wasn't too hot and was a really relaxing temperature. Infrared saunas are supposed to boost the body's circulation by penetrating the body's soft tissue, and also relieve muscle pain and reduce stress.Instead of heating the air around you, infrared saunas penetrate the human tissue.There is limited research on them, but some small-scale studies such as this 2015 one by Kagoshima University in Japan, found they may help decrease muscle soreness.The vibe is luxurious and sleek, and the top-of-the-line equipment is impressive.But for the price of £16,000 ($21,800) a year, members would surely expect nothing less. For that price, you'd want to feel safe in the knowledge you're getting the best of the best in terms of experts, treatments, and equipment. You might expect some complimentary hair-ties too, but maybe they're still to come.The Body Lab's offering is impressive — having everything under one roof is a real selling point for busy people, and I certainly walked out feeling good.The prices are far from affordable for most people, but for those who have the money, visiting the Body Lab might be a comforting way to spend it.