If you are currently eating lots of sugar, fast food, etc. and then switch to clean, unprocessed low carb foods for ten days, then I imagine weight loss would be fairly quick. But if your current diet is higher carb but at least healthy, then it might not be quick. Also depends on how much you want to lose. 10 days is generally not long enough. And the weight will obviously come back without long term goals.
Very little to no carbs: meat, organs, eggs, butter, broth, veg that grows above ground.