They need to cut calories and therefore must first be able to control their intake (counting calories). Then they can cut 400cals per day, If that does not work, cut 600-800cals. 200cal steps. This always works.
For a person whose body is pumping full of cortisol, thus pumping also with raised glucose and insulin levels, gradually cutting calories can results in even higher stress response, lethargy, disrupted sleep patterns, reduce satiety triggers, changed apatite towards fat and sugar, and a bunch of other problems that all contribute to the opposite desired effect of loosing weight. A body in panic mode will do about everything except loosing weight unless it is actually medically starving.
Edit: I also realized that there are major environmental differences, like where I grow up most people which where obese did try to eat less and do sport and as such the ones which are still obese are often not so because they don't eat proper and don't do sport but because they have other health issues.
Go on a low carb / ketogenic diet instead. You get to eat lots of protein and fat. You will automatically feel less hungry but also, once ketosis sets in you will have a surplus of power that you can uses for physical activity. Added bonus, your body will react to insulin again.
Yes, what I can say it will be harder for some persons than others. The hormonal environment in the body can not be disregarded and can be either disrupted or genetically different. STILL, restricting your eating habit (caloric deficit), will.always.work.
> Go on a low carb / ketogenic diet instead
Agree, it's the easiest way to lose weight. Cut out processed food, added sugars and rice/potato/bread, and the weight will drop off very easily. No need to count calories because it'll be very hard to eat too much as long as we cut out the above.
As often understood, the latter. Two factors (there are others): metabolism of fat, sugar, and protein are hormonally (such as insulin) and differentially dependent, as well as the storage of excess calories.