Ketogenic dietKeto diet

A ketogenic diet restricts carbohydrate severely — typically under 50 grams a day, sometimes much lower — with moderate protein and the remainder of energy from fat. The restriction is enough to induce and sustain ketosis.

It matters because it has a genuine, well-established medical use in drug-resistant epilepsy, and a reasonable evidence base for short-term weight loss and glucose control. What the controlled evidence does not show is a metabolic advantage: when calories and protein are matched, fat loss is comparable to other diets, and early rapid weight loss is largely glycogen and its associated water.

In practice its trade-offs are specific. High-intensity training performance often suffers because glycogen is the fuel for it; fibre and micronutrient intake need attention; and adherence over years is poor in most trials. It suits some people very well and others not at all, which is an argument for trying it rather than believing it.