I found it was much easier to cut my daily calorie intake and increase fat burning by skipping an early breakfast and regular lunch and moving to coffee for hunger suppressant, a low-carb brunch and some other low-carb afternoon snacks instead. Before dinner, I do about 20 mins of mostly body-weight exercise. Then have a regular dinner including carbs and then some more high-glycemic carbs. Keeping low-carb for a long continuous part of the day lets your body burn a lot of fat for fuel, and it's easier to deny myself those things I like to eat if I know I can have them later in the day, and it's a very nice carrot to do regular exercise. I've also had the impetus to discover low-carb recipes I enjoy, making it a nice feedback loop. To help this process I began by going two weeks without carbs, as that was recommended to help get your body used to burning fat for fuel. I've enjoyed a much improved body composition and it's still getting better.
Losing weight is not that simple. A short term effect can be made easily. But after a while, your bad habit will drive you back and even your body will feel better to stay at a certain weight, refuse to reduce more. The worse case is it usually bounces back. So short term weight loss does not count.
This is a problem that so many people are fighting against, and mostly we are losing. Exercise may help, eat less may help, they are not ultimate solutions. The fundamental thing or the root cause is that our metabolism becomes slow which tends to accumulate more fat, and the energy being absorbed from food is not enough per meal, so we tend to eat more. Increasing the quality of food without junk, all organic and fresh, no transgenes, no trans-fat, is the ultimate solution along with regular exercise. But we may not be able to afford or be willing to pay the cost for staying healthy. It has a long term impact.
It's hard on a non-intellectual level. Humans - even highly intelligent ones - don't work on pure logic. Why do people smoke? It's deadly. It's not logical. Same applies to overweight, sport, drugs, etc.
You have an interesting point. If we think we are rational enough to do things according to the right logic, there are still a lot of chances we fail. Most of the case, it's hard to control our body to follow logic because we are not only driven by our brains.
But it is, that's my point. If I went out and jogged instead of being on HN, and cut my portions by 25-30%, I'd be fit as a fiddle. But I simply don't do it because <excuses>. There's nothing complicated about it at all.