So with all of that in mind, you may still be wondering what you can expect in terms of true fat loss per week. A lot of it, actually, will depend on where you're starting out bodyweight wise (activity also factors in), as that determines your maintenance caloric level.
A 165 pound male with normal activity patterns may have a maintenance requirement of about 2700 calories/day. At 800 calories/day on this diet, that's a 2000 calorie/day deficit, 14000 calories over a week, 28000 calories over 2 weeks (note: there is a slowing of metabolic rat that reduces these values somewhat). Assuming all of the true (non-water) weight lost was fat (it won't be), that should be an 8 pound fat loss in 2 weeks (28,000 / 3,500 = 8) or approximately 2/3rd of a pound of fat lost per day. The true fat loss will be lower because of various inefficiencies and the slowdown of metabolic rate (which can start after only 3-4 days of severe caloric restriction).
A larger individual, say 250 pounds, may have a maintenance caloric requirement near 3,750 calories per day. At 800 cal/day on this diet, that's a 3,000 calorie/day deficit. Over 2 weeks, that's a 42,000 calorie deficit, divided by 3,500 calories/pound of fat equals 12 pounds of fat. That's on top of the 10 or more pounds of water that may be lost.
Females or lighter individuals with their generally lower maintenance caloric requirements will lose less. True fat losses of 1/2 pound per day or slightly less may be all that they get: that still amounts to a considerable fat loss (7 pounds over 2 weeks) along with the extra water weight loss.
The bottom line being that an approach such as the crash diet can take off both fat and weight far more rapidly than less extreme diets. And while I still think it's generally better for dieters to take the long-approach and use less extreme diets for longer periods of time, as I'll discuss in the next chapter, under some circumstances, crash dieting can be beneficial.
Was this article helpful?