If you want to lose weight through diet you have to eat less.
Professional clinical nutritionists will not necessarily agree with you that this is the only route to salvation here; it is just as important to choose the most appropriate things to eat and to avoid, the timing of one's ingestions, the balance between carbohydrate, protein, etc. intake, the extent, type, frequency and timing of exercise compatible with the diet concerned and various other equally relevant issues; furthermore, the physical condition of the patient, including particular ailments that respond in certain particular ways to dietary régimes, is a vital consideration. In other words, it's far more complex than your bald statement that anyone who wants to lose excess weight should simply eat less food than they do.
Although what I am about to write is in some degree an aside from your particular point, it is also worth mentioning that losing weight through diet (which you write about) is only possible as a kind of dietary counteractive measure; in other words, one is unlikely to lose excess weight through dieting in a particular and appropriate controlled way unless that excess weight has been acquired by inappropriate dietary practice in the first place (which I admit is often the case, but by no means always so).
What do you have to do with it? I attack hoax diets. People that make millions claiming some specific way of eating makes you lose weight.
I agree with you entirely here, hence my remarks about the need for some overweight people to consult and act upon the individual personal advice provided by medically qualified nutritionists rather than resorting to the kinds of quick-fix dietary scams against which you so rightly inveigh.
I say one should diet by eating less. Less than who? The amount they already eat.
But see above; this works only in some cases where excess weight is the result of excess intake quantity only.
You are also Scottish. Great! Ha.
Nice that it's appreciated. That said, several surveys have in recent years revealed (rightly or wrongly) that the Scots have the worst dietary practice in Europe; shameful as that statistic is, let me hasten to assure you that, although I am not all that fit, I am thankfully not one of those who suffers from that kind of dietary self-abuse.
Best,
Alistair