LOSING 4+ PER WEEK?

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Someone on mfp posts she is doing Whole30 and eating only organic and basically no carb. She said this is the way to go and has lost 37 pounds in 8 weeks on this plan.

Two questions:
I cannot wrap my mind around 37 pounds in 8 weeks and am really conflicted. Is it possible to go from 259 to 222 in 8 weeks while eating 900 to 1200 of organic etc?

Is it sustainable and healthy?

Thank you!