Richard Johnson explains how low-carb diets work by reducing fructose production in your body. When you eat fewer carbs, you make less fructose, which decreases leptin resistance and stops weight gain. Salt also triggers the pathway that converts glucose to fructose, which is why animals at salt licks gain weight.
Chapters
Now, we knew that, you know, low carb diets, why they work so well. If you go on a low carb diet, you can't make fructose very well, because you make fructose from carbs. So if you're on a low carb diet, you can't make fructose, and people lose weight. You can be on a high fat diet and a low carb diet, and you won't gain weight because you don't get leptin resistant, because it's the fructose that makes you leptin resistant. So this could explain this whole low carb story pretty well. But then we started getting interested in other ways that this glucose path, or this conversion of glucose to fructose can happen. And we realized that salt is actually known to be a mechanism for activating the enzyme that converts glucose to sorbitol and to fructose. And animals love salt licks. And when they find a salt lick, it's been shown to help them gain weight.