Part one — the spine
Why a ketone gets bound to a mineral at all.
Beta-hydroxybutyrate on its own is an acid. You would not want to swallow it, and it would not keep on a shelf. Binding it to a mineral produces a stable salt — which solves the storage problem and, more usefully, means the mineral comes along for the ride.
That second part is the whole design argument. The three minerals chosen here are not arbitrary: calcium, magnesium and sodium are precisely the three that drain fastest once carbohydrate intake drops and insulin falls, because the kidneys start excreting more of them. Anyone who has cut carbohydrates and spent a week feeling foggy and heavy-legged has met that mechanism without knowing its name.
So the spine does two jobs with one ingredient class. It puts a fuel signal in front of the body that the body already produces for itself overnight, and it replaces the electrolytes that the change in eating is quietly costing you. Neither of those is a weight-loss mechanism. They are the reason the first fortnight is survivable enough that you reach the weeks where the rest of the formula matters.
Worth being clear: exogenous ketones are an active research area, not settled science, and the trials that exist vary enormously in dose and design. This overview on PubMed is a reasonable starting point if you want to read past the marketing.