I recently finished up a cut. Overall it was a success: I lost about 10 pounds of fat and went from around 12% body fat down to close to 7%. But it took a lot longer than it should have and I made a lot of mistakes along the way. Here are 4 lessons I learned the hard way:
Follow these tips and start your cut right
Use the right calculator, use it correctly
To find my maintenance caloric needs, I started off using a spreadsheet I found on Reddit. Unfortunately I inaccurately calculated how much energy I was expending during exercise. This added an extra 450 kcal to my maintenance estimate so for several weeks I wasn't seeing results.
Watch your leptin
I tend to take things to extremes, wanting to see results as quickly as possible. So for a while I was eating between 750-1000 kcal under my maintenance needs. That in itself is fine (well, 1000 kcal under is ok for a couple of weeks), but what I didn't realize is that long periods of caloric restriction can eventually affect your levels of a hormone called leptin. With low leptin, you'll get hungry more often, feel tired and lose less fat.
Do a carb refeed to boost leptin back up. Specifically spend one day eating more carbs than usual. Increase calories consumed by 20-50% specifically with carbs (increased protein or fat won't increase leptin). Going for 100g extra carbs on that day isn't unreasonable.
At one point I was so concerned with strength loss while restricting calories that I was lifting 7 days a week. Don't do that. It's dumb. When you're consuming reduced calories it takes your body longer to recover. I eventually switched to a 4 day / week split with significantly reduced training volume (instead of doing 5x5s I warmed my way up to sets of 1-3 reps on the big lifts).
It's important to keep intensity high (keep lifting heavy), while reducing your volume. This tends to preserve muscle better.
Use fasting to your advantage
When you lose overall bodyweight, you lose either fat or muscle. Using intermittent fasting can reduce the amount of muscle loss down to a minimum.
I'm a big fan of daily fasting for 16 hours and eating your calories within an 8 hour window (a timing schedule that comes from the Leangains method).
Another thing you can do on non training days is a 24 hour fast. Again, the goal here is focusing your loss in bodyweight on fat vs muscle. Your caloric deficit over the week determines how fast you lose bodyweight. But fasting can control that ratio.
Doing a cut isn't that difficult at a high level. Eat less calories than you need and keep lifting heavy. But the details matter. Hopefully with the above guidance you can avoid making the mistakes I did and you'll be in for a much smoother process.