Not necessarily "horse shit". We know sugars produce insulin responses. We know insulin causes growth/weightgain. We know carbs most directly convert to sugar,

Not necessarily "horse shit". We know sugars produce insulin responses. We know insulin causes growth/weightgain. We know carbs most directly convert to sugar, followed by protein, followed by fat. So in theory you may be able to eat more fat and protein without gaining AS much weight. Now if you are at a calorie deficit you aren't going to gain I agree with that but I can consume more calories of high fat / low carb and still lose weight. The bottom line with dieting is find something that works for you.