The Londoner signed up to newbodyplan.co.uk and got in the shape of his life in time for his 40th birthday.
“I was fast approaching 40,” Clark tells Men’s Fitness, “with an expanding waistline and clothes that were once loose now feeling far less comfortable.
“I’d spent a lot of time in the gym trying to rediscover my hips under the layer of fat covering them, but what I was doing wasn’t working, so I decided I needed to take control.
“I’d worked with personal trainers and they’d all helped in the gym, but when I told them I don’t eat meat it was always met with silence or comments like, ‘Maybe you should just try some chicken.’”
Clark signed up to a New Body Plan body-transformation challenge, and immediately started a four-days-a-week weight-lifting routine – with sessions lasting no longer than 45 minutes.
“The sessions were demanding and I always finished with a good sweat, but they were enjoyable as well – they pushed me but in a good way,” says Clark.
“And the changes I’ve seen are huge. It’s a massive sense of achievement, because it genuinely has changed how I feel about myself. I feel a lot more confident and I look a lot healthier.”
While some prefer long, slow jogs for their cardio kicks, New Body Plan creator Jon Lipsey favours a short and sharp approach.
“The single best way to reduce body-fat levels is resistance training,” he says. “That could mean lifting dumbbells, or doing bodyweight press-ups and squats, combined with high-intensity interval training.
“These two types of training burn calories not only during training but for hours afterwards, and help build lean muscle mass, which further increases the number of calories you burn.
“The combination of losing fat and building muscle is why David was able to radically transform his body is such a short amount of time.”
After years of veganism, Clark praised the New Body Plan’s flexible approach to food for helping him – for the first time in his life – eat for a healthier body, and cut back on booze.
“I re-learned how to snack,” he says, “and doing the programme changed my attitude towards alcohol I realised it was the longest I’d gone without having a drink since I was 18. I thought it would be harder than it was to break that habit of having a glass of wine or a couple of beers just because it’s a Friday night.”
Clarke adds that now he feels like he’s “in control” over what he eats and when.
“Being in control is so important,” he says, “especially at a time when so much seems out of our hands.
“That’s made my transformation even more satisfying – to feel like I’ve taken back control and have direct ownership of my own body.”
Kick-start your own body transformation by taking the newbodyplan.com New Body Quiz.