1. You want to lose fat not weight
2. Permanent lifestyle changes have to be made. No point losing 'weight' and then going back to eating crap again and putting on even more weight on than lost
3. The key is to decrease your energy intake but done in a way so that you don't become hungry.
4. Planning is key. You don't need to think about what you are going to eat this evening because you already planned it the day before.
5. Develop a routine for meals and gym such that they are integrated into your life. Sort of like brushing your teeth, you don't have to think about it, you just do it.
I lost 44 pounds of FAT in a year and now have defined abs (6 pack). Atm on a bulk, gaining on average about a pound of muscle a WEEK.
Good job there !
As of OP 20lbs issue, I have quite a bit of experience over the years taking my weight back 10 to 15lbs ( I usually aim for 182/183lbs body weight, where i feel pretty good and used to perform well, but when careless I tend to fatten up and usually react somewhere before 200.
Have been going on like this for 14 years, except lately, where I've started blowing up but largely willingly.
Sports help a lot controlling body weight, yet:
While not doing sports I've been succesful with low carbs diet to lose weight, than maintain weight like below.
While doing cardio intensive sports, it's even easier to shed 10/15lbs, usually following a balanced diet and just switching to mixed salads for evening meals is enough ime. I've never been keen on running outside or on a threadmill, but just playing with a tennis coach a bunch of hours per week can do wonders (like make one lose more weight than they wished). Drills from the coach seem to help there, just playing tennis games with friends appear less energy intensive. If one is game for it, 8 to 10 hours per week fighting sports training should do wonders fatwise. No doubt plenty of sports will keep one's waistline within decent limits, I see many rather fit and slim middle age individuals and they seem to enjoy different sports.
Not so difficult to maintain the weight even without long work out hours as long as evening calorie intake is moderate ime, hence every time I go on vacation, while stopping doing sports and without Missus' huge salads on the evening I tend to put on weight. Booze seems to wreak havoc, but it's also linked to higher and unhealthy calory intake in the evening.
I suspect when it comes to 20lbs, the same process could work fine although it needs to be held on longer. Fwiw it's more fun to cut weight through a sport one enjoy (and can still perform, that part doesn't get any better with age) than only through diet (again i mostly know the carb cutting ones), better react before there is too much weight to lose.