Is a soup diet sustainable?

I was planning to do this because I'm on holiday in 4 weeks. I know, I should have worked out and ate better way in advance, but my long days at college were just so stressful that being healthy was impossible ( the cafe just pretty much sells fries,pizza and chocolate) and I was always tired when I got home as I'm on my feet all day, doing people's hair and what not. I know that sounds like an excuse, but I don't know any one who feels like eating healthy or exercising when they're under a lot of stress (even though it reduces stress lol). I was just wondering if this diet is worth it or not? I'll be having one meal a day and substituting the others with soup and combining it with exercise alternating between one hour and half an hour each day. Is this a good plan? Or not? Just want to look half decent on the beach honestly :)
Is a soup diet sustainable?
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