I'm pretty sure that's why low carb/keto diets work: they force you to avoid most processed junk food. However I don't think it has to do with carbs. I'm pretty sure you could get the same results eating potatoes, corn, beans, rice, etc.

4 years ago I did a strict no-carb diet for about a year and lost 40 lbs. Then I started eating only starches I had cooked myself - potatoes, rice, beans, some pasta, etc. I gained it all back. I'm doing it again now and have lost 35 of my original 40, but I have no intention of re-introducing starches into my diet afterwards. Aside from the weight control benefits, keeping starches out of my diet makes me feel so much healthier, it's insane. I eat lots of green vegetables, nuts, meat, eggs and a small amount of full-fat dairy. Cured or salted meat doesn't seem to be any worse than fresh meat, but most of what I eat is just plain fresh grilled steak or chicken.

I'm pretty sure you can't. Potatoes, corn, and rice don't make you feel full and satisfied for long, and the surprisingly high rates of diabetes and obesity in low-income agricultural communities suggests that their high-carbohydrate, low-fat diets aren't exactly the healthiest.