Calories in, calories out (CICO) will certainly work for weight gain or loss.

But cardiovascular exercise, muscle strengthening, etc do confer other whole-body benefits that going for the french fries won't convey.

Reducing calories on the plate was way easier for me too.

It was both important to control portion size as well as content though.

So for me, the key point was adjusting my meals to make me feel fuller, so I could reduce portion sizes without feeling hungry.

I primarily did this by increasing the relative amount of protein and fiber, and trying to reduce fat or carbs.

For my saturday steak I swapped french fries with peas, and cut the butter for the bearnaise in half.

For my "tacos" I limited the number of tortillas, increasing the amount of salad and also swapping out regular iceberg lettuce with romaine (more fiber). I also stopped using additional oil or fat for cooking the mince meat.

For breakfast I swapped butter for mustard or similar, and tricks like using more mature cheeses so I could use less cheese while still enjoying a lot of flavor.

I think the important thing is being honest with yourself about your goals and limitations, and use that to find something you can live with.

I just had to have that saturday steak, but I identified what about it that was important and as such managed to tweak the dish. I knew I couldn't cut chocolate entirely so instead I found ways to get the chocolate I needed while having far less of it in total.

Absolutely true.

At the same time I've noticed I'm much hungrier if I don't exercise. And exercise displaces time I could be eating. So, at least for me, it seems to have an indirect impact on weight loss.

I can't the exact details but IIRC there is a canonical study which tracked physical activity, calorie intake and obesity in large cohort. There was a high correlation between calorie intake and level of activity in the sample and likewise only a weak correlation between level of activity and obesity (or lack thereof). Basically, people were good at calibrating their calorie intake to their level of physical activity. EXCEPT for the sedentary people, who tended to consume calories way outside of their needs based on little or no physical activity and (not surprisingly) tended to be obese at high rates.

Our bodies seem to be good at calibrating hunger and calorie intake to maintain balance between calories in and calories out, but there is something about being completely sedentary which causes that mechanism to malfunction.

It depends whether your goal is health or aesthetics. If you are after health, moderate about of sport is working intervention. It actually works to make you healthier.

If you go only diet route, you may or may not become healthier.