Another point I just thought of. It seems the focus is on calories, with fat and volume of food being merely proxies for calories, i.e. fat contains twice the calories as carbs, therefore eating less fat is the best way to eat less calories. The whole deal with calories is gaining and losing weight in the context of obesity. The whole deal with obesity is that it's blamed for a bunch of other diseases, i.e. obesity becomes the cause.

Low-carb is shown to do two things right off the bat, before we measure anything else. First, we lose fat. Obesity is fixed, conformance with prescription is established. Second, we eat less. The calories focus is adhered to, conformance with prescription is established again.

The fact that low-carb means to eat more fat could arguably be pointed at as failure to conform. However, since eating less fat is merely a proxy to the main prescription which is to eat fewer calories, the method used to eat fewer calories becomes irrelevant, so long as the effect is the same - we eat less.

If we argued that other measures are the focus, for example disease markers such as cholesterol and triglycerides and HbA1c and blood glucose and blood pressure and you-name-it, low-carb actually fixes this even in the absense of weight loss.

The best part is that there is actual genuine experimental evidence published in reputable scientific journals to support all of it. This ain't just a game of show your food log from yesterday.

Eating less fat (especially less saturated fat) could be argued as a way to prevent heart disease, so that low-carb could be argued to accelerate heart disease. However, since heart disease is deemed to be subsequent to obesity in the grand idea about calories->obesity->all other diseases, it becomes moot.

Just illustrating the logic, not arguing a hypothetical case.