I've recently been seeing versions of things like "Weight loss for women is most difficult when you get under a BMI of 30" and "Weight loss is hardest for women below 30% BF".
Where did this 30 number come from?
How true is it?
I guess there is some truth to that saying, especially if you started out at like 40+ BMI range. Someone at that high BMI could easily lose weight by simply cutting their calories down to 2,300 calories a day, and could easily drop 2-4 lbs a week. Hell, lots of the death fats on KF could consume 3,000+ calories a day and still lose a lot of weight quickly.
Once you get to the mid 20s of the BMI though, you don't have a ton of excess fat for the body to quickly get rid of, so it does become "harder" in the sense that you can't keep losing 3 lbs of fat every week like you could when you were in the 40+ BMI range. Eventually, eating 2,300 calories will simply put you at a maintenance weight, rather than continued weight loss. And at that point, if you want to keep losing weight, you either have to up the exercise or cut more calories. Unless you want to end up an ana-chan, you would also have to settle on a more modest weight loss goal of losing half a pound a week. I'm sure that can feel frustrating, when the closer you get to your goal, the slower you have to go.
How should you change up your diet/weight loss scheme once you hit that number?
What if your starting point is that number?
If I was at that starting point, I would find out my maintenance weight calories, and cut 300-500 calories from there. So if I'm staying at my weight at 1,800 calories a day, I would change it to 1,500 a day.
But tbh, I'm too lazy to count calories, so back when I gained 20-30 lbs at college, I just started fasting and I was back to normal in a few months. These days, I keep weight off by eating the same meals every day. Lots of people think this is boring, but it really isn't, and you can still eat unhealthy shit, you just don't eat it every day.
If I end up eating a yuuuge surplus of calories (due to the holidays or whatever), I plan a 2-3 day water fast afterward. It's been working for me for years.