Anything lost very quickly is likely to be through dehydration as opposed to burning stored fat. …which means it’s not sustainable.
Generally accepted guidelines for safe and effective weight loss are 0.5 to 2.0 pounds a week. With one pound being about 3,500 calories, that’s a caloric deficit between 1,750 and 7,000 calories to attain that loss.
my personal experience: 20 lbs in 4 weeks. I had severe pneumonia, was hospitalized for a week and have absolutely no idea how I could have possibly lost that much weight in such a short period of time.
It was probably a result of dehydration, limited caloric intake and the body using an amazing amount of energy to fight the intruder.
Not a way I recommend!
My understanding of the studies that I have read is that the quickest weight loss is not well correlated with keeping it off the longest.
Of course, the promise of quick weight loss has been used for a very long time to sell magazines and books and exercise equipment and supplements…. But I think part of our role as professionals who work on wellness and health is to promote a more reasoned expectation and process.
The nutritionist I most admire for her professionalism and knowledge (and the one I recommend to students who are interested in nutrition and weight control) underscores that as well.