She's struggled in the past with yo-yo dieting. And after a lifetime of diet woes, Oprah Winfrey has given a candid insight into her weight loss struggles, delivering a powerful speech in a new advert for Weight Watchers. The 61-year-old speaks frankly in the emotional video, which shows the star at various sizes, as she hopes to inspire people to start their own weight loss journey. Showing off her svelte new figure in a cream suit with suede trimming, the talk show host explains: 'Many times you look in the mirror and you don’t even recognize your own self because you got lost - buried - in the weight that you carry.

'Nothing you’ve ever been through is wasted, so every time I tried and failed, every time I tried again, and every time I tried again, has brought me to this most powerful moment to say, "If not now, when?"

Looking directly down the lens and pleading for others to take control of their diet, she concludes: 'I feel that way, and I know millions of other people feel that way. Are you ready? Let’s do this together.'

Oprah is a passionate follower of the support group Weight Watchers, and became a spokesperson for the brand in October, as well as paying $43.2 million for a 10 percent stake in the company.

The television personality first joined the group in August, and managed to shed an impressive 15lbs in a month.

Speaking about her decision to work with the company, she explained: 'Weight Watchers has given me the tools to begin to make the lasting shift that I and so many of us who are struggling with weight have longed for.

'I believe in the program so much I decided to invest in the company and partner in its evolution.'

It's clear the star is taking her weight loss routine seriously, sharing pictures of her healthy meals and workouts on Instagram.

At her heaviest, Oprah weighed 237lbs, and her weight continued to fluctuate, until earlier this year when she began to shed the pounds gradually.

And the star famously lost 67lbs in 1988, dropping down to a size 10 after living on a liquid protein diet.

Proud of her weight loss, she even wheeled out a wagon loaded with fat on her eponymous talk show, which represented all the weight she had lost.

However, the star has gone on to publicly say she regrets her unhealthy fad diet.

And the results were shortlived, as within two days of returning to a diet of solid foods, Oprah could no longer fit into a size 10.