One day she told me that the leader of her slimming group told her that she wasn't losing weight because she wasn't eating enough.
Now that's a line of business I should get into. That group leader will have clients for life!
That's actually legitimate, to an extent. If you consume too few calories, especially when combined with exercise, your body goes into "starvation mode" and starts putting away calories as fat at a far higher rate.
If that were true 1) anorexia would be physically impossible 2) you would be violating the laws of physics.
Not really. If you drew a graph of weight loss on the Y axis and calorie intake on the left axis, it's not a straight line - for many reasons, including how your metabolism slows down.
Of course, anorexia is at one end of the spectrum, where your intake is SO low and your body is SO thin that you are killing yourself.
But when I was in my early 30's, I embarked on an attempt to lose weight, and I pretty much thought it was impossible.
But it wasn't. I used weight watchers, the weight fell off in about 5 months (50+ pounds). Near the end I was losing at about 0.5 lbs a week. When I hit 127 I said "I'm good" and I started adding in more "points" (calories) for maintenance, and then the pounds started dropping even faster, more like 2lbs a week. Had to keep adding even MORE calories to level off.
This "value" or "number" is totally going to depend on your own metabolism, age, activity level, sex, etc (we are all our own special snowflakes). For example, it's now 13 years later, and that "number" (whether it me maintenance or weight loss or whatever) for me has dropped a good few hundred calories a day. I'm going to draw a picture.