I think a "diet" infers something special or special attention which is paid to the food you eat and the quantity, where some sort of restriction is put on it. if someone was not on a diet, you would assume they could eat any food in any amount. The word 'diet' could be a fad diet or just one where dairy or wheat is removed due to an allergy. Reducing your intake by eating smaller meals and no snacks is still a diet, as there is a reduction in quantity!
My opinion is that most diets do not work- the faddy ones. You need to be able to eat what your body is craving, so cutting out whole food groups is too hard to do long term. I have found the only way to lose weight is to, ironically, eat no snacks, and smaller meals! But keep the food basically the same, so your diet is balanced. Avoid sugar and choc as it mucks up your system. A couple of weeks without it and you will never crave it again! Then you are back in tune with your body and if you listen, it will tell you if it wants vit c, calcium, carbs, protein and most importantly, it will tell you when it is full. Sugar mucks up those signals, as does empty pointless food like crisps. Just eat 3 meals a day, stop when full, and you should lose weight.