"Keto supplements" is a big category. Some contain ketones, others contain apple cider vinegar or other ingredients. Before you buy, it helps to know what each type is designed to do, and what no supplement can do on its own.

What happens in your body on keto

On a normal diet, your cells run mostly on glucose from carbohydrates. When you cut carbs very low, your body breaks down fat and the liver makes ketones. The main ones are beta-hydroxybutyrate (BHB) and acetoacetate. This state is called ketosis.

The two main types of keto supplements

1. Exogenous ketones (BHB)

"Exogenous" means the ketones come from outside your body. They are usually sold as:

• Ketone salts: BHB bound to sodium, calcium, magnesium or potassium. Usually powders or capsules.
• Ketone esters: a liquid form used mostly in research. Strong-tasting and less common in stores.

Studies show these products can raise blood ketone levels for a few hours. But raising ketones in your blood is not the same as burning your own body fat. Research on exogenous ketones and long-term weight loss is still limited, and results so far are mixed.

2. Apple cider vinegar (ACV) supplements

ACV gummies and capsules are popular with people on keto because ACV has almost no carbs and is easier to take than the sour liquid. Research on vinegar is small but interesting, mainly around meals and fullness. ACV supplements do not put you into ketosis by themselves. Gummies also contain a little sugar, so count it in your daily carbs.

What keto supplements can't do

• They don't replace a low-carb diet. Ketosis comes from what you eat.
• They don't cancel out extra calories.
• They are not a treatment or cure for any disease.

How to choose one, if you want to

• Read the ingredient list: know if you are buying BHB, ACV, or a blend.
• Check the serving and carbs: especially for gummies.
• Pick a form you will take every day: see gummies vs capsules vs drops.
• Compare price per bottle: multi-packs usually cost much less per bottle. See how to choose your pack size.

The bottom line

Keto supplements can be a convenient part of a keto routine, but the diet does the main work. If you have a health condition, take medication, or are pregnant or nursing, talk to your doctor before taking any supplement.